2

Discussions of Papers Published in Vol. 33/1 and 33/2

SESSION ON CUTTING

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PAPER C/3

Were the savings achieved by the system due to improving the cutting conditions and tool selection? If yes, what is the ratio of savings contributed by each of the two methods ?

Page I I

A.KINNANDER. I.SVENNINGSSON/B.COLDING "Strategies to control variations in machinability in mixed manufacturing".

Q~!!~~i~~_fr~'E_ e!~ !_y~~ _Q~~_~ !~b~~

Our manufacturer's experience (computed at a time where there were no machining centers) is that it is very dangerous to base the normal cutting data on an averag- in machinability ratings. When we received better than the average batches of steel. the cost of machining was decreasing slightly. But. in case of worse batches of steel. the cost was increasing tremendously. due to all the burden coming from the more frequent tool failures. For the types of machining we currently make; there is now no possibility of monitoring (small end milling operations peripheral cutting). ~~~~!!r_fr~'E_~!~!~~~~Q~~

We agree with your opinion to a great extent but should like to comment a few points. I f we are going to machine a larger batch of components made of a material far beyond the average machinability we should definitely use strategi 3. The paper should be regarded as a theoretical and realistic analY5 to point out what type of technique that should be used to control variating machinability. We don't claim that this technic today is 50 developed that it can be used in every machining operation. Q~!!~~i~~_fr~'E_e!~~b~~~!~~~~~

The paper deals only with the variability of the tool life equation. Machinability data is affected by many other factors such as workpiece holding. type of machine etc •• In order to apply the strategy of average machinability data as proposed in the paper. it is necessary to assess the machinability variation, taking into account all the factors affecting the machining system. The main problem seems to be in assessing this machinability variation. What is your cotm1ent about this problem? ~~~~!!r_fr~'E_~!~!~~~~Q~~

It is difficult to get a correct measure for machinability especially for a specific operation in a specific machine. However, if some kind of machining monitoring is used the actual tool lifes can be stored and the machinability with scatter can be calculated. PAPER C/7

Page 29:

V.A.OSTAFIEV, A.V.GLOBA, L.S.GLOBA IT. N. LOLADZE "Integrated end milling optimization development".

Q~!!~~l~Q_fr~'E_e!~~b~~~!~~~~~

For model building using data from the production floor. the machining variables are to be altered. How are the data at various conditions obtained from the production environment. ~~~~!!r_fr~'E_Y!~!Q~!~E!~Y

Of course the data must be altered to get some relationship between the metal cutting parameters. The data for calculation were taken from machining different workpieces under various conditions. The calculation of the various relationships were performed only after long term collection. gY~~t12Q_fr~'E_8!~~8!~~!~

What was the tool life criteria? What was the size of the wearland ? ~~~~~r_frQ'E_Y!~!Q~!~E!~Y

The tool life criteria was end mill corner wear. The wearland size on the clearance surface was 0.5 to 0.7 mm depending on the cutter diameter.

Annals of the CIRP Vol. 33/2/7984

~Q~~!!r_f~'E_Y~~!_Q~!~Em

The method proposed optimizes cutter path, cutter diameter, depth and width of cut. speed and feed. We did not divide the optimization process for cutting conditions and tool selection. The cOllll1On savings are a 1.5 to 2 times reduction in operation time even for simple workpiece shapes. PAPER C/o

Page 33:

S.KALDOR, P.H.H.TRENDLER, T.HOOGSON IG.F .MICHELETTI "Investigations into the clearance geometry of end mill s" •

Q~!!~!i!!!!_f!:!!T_§~~~B8Q~

Have you undertaken any tests on commercial cutters ~~~~~r_fr2T_!!~QQ§~Q~

Further investigations were carried out, in collaboration with three manufacturers in various countries, to determine the influence of clearance angles on the performance of eccentric and flat ground end mills under different machining conditions and with different work materials. All the results have shown exactly the same behaviour: a linear increase in tool life, based on flank wear, in relation to the clearance angle. Test results showed that up to 10° the tools reach the pOint of total failure while from 12° up to 24° all tests were stopped when the selected flank wear value was attained. We believe that an optimum will be reached at higher clearance angles and thereafter a drop in tool life due to fracture is expected. It would appear that the higher optimum clearance angle in this case results from the relatively stronger tooth configuration of the spiral fluted cutter. PapersC/l',C/'2 Pages47/51 : C.A.VAN LUTTERVELT, H.WILLEMSE A.J.PEKELHARING "The Exit Failure of Cemented Carbide Face Milling Cutters". Q~!!~!iQ~_frQT_~!~~~~g~~gM~~

Was there any attempt made to measure the forces or contact length at the exit region so as to interrelate average stresses with tool chipping? ~Q!~r_f!:2~_~!~:_Y~~_b~!!~BY~b!

Such attempts were made occasionally by making high speed films of the chip formation simultaneously with measuring cutting forces. However, this input is not sufficient to make more than a very rough estimate of the resulting stresses in the tool. Such experiments can only be made in orthogonal cutting and the results are not sufficient to explain all observations made on the influence of geometry. speed and feed in a three dimensional operation like face milling. Q~!!~t!2!!_fr2~_~!~!~!Mb~

Can you give any reason for the fact that the influence of cutting speed on the "Safe Area" as shown in Fig.3 paper Clll is not present in Fig. 3 of paper C/12 ? ~~~r_fr~_~!~:~~_b~!~B~~b!

In Fig.3 of paper Clll an increase of cutting speed causes I reduction of the width of the dangerous zone. In general this tendency is also found in Fig.3 of paper C/12, espeCially if the cutting speeds of 100 and 125 mlmin are compared. A possible explanation is that at high· cutting speeds an increase in cutting speed causes further softening of the built-up layer between tool and chip. A soft built-up is not able to transmit the "negative" friction stresses between chip and tool face which means that the stress peak in the tool remains lower. On the other hand, if the cutting speed is too Iowa built-up edge may be present. Now the negative friction force is exerted

553

by the chip on the BUE and is spread over a wider area on. the tool face. The stress peak in the tool is thought to be lower 1n that case. The consequence is that there is a range of cutt1ng speeds in which the danger of ex~t failure is ma~imum. Unfortunately this range of cutt1ng speeds 1S qU1te.close.to the range of cutting speeds considered to be the econom1C opt1mum today. g~~~!!9~_fr9~_~~~Q~~~Q~~!

1. What is the effect of a chamfer (~111111) on exit failure? 2. What is the role of stiffening the tool holder system on entrylexit failure? ~~~~UrQ~_~~~~~~~_hYm~~~h!

1. In general the presence of a chamfer or a rounding on the cutting edge is beneficial on the tool life in the so-called dangerous situation. However, much depends on the macrogeometry of the tool and the exact dimensions of the chamfer or round1ng. Up to now we were not able to determine which were the optimal dimensions of chamfer or rounding in three dimensional face milling. The best values obtained in a two dimensiona~ t~rning experiment does not necessari ly be the best 1n face ml1llng. The real question, however, is even more complicated. The general finding is that if you increase the chamfer or the .. rounding of the cutting edge the tool will become less senS1t1ve for tool failure due to dangerous exit conditions. However, cutting forces and tool wear are also increased as was proved by HOVINGA (7). This means that the selection of.the opti~l dimensions of cutting edge roundness or chamfer 1S a quest10n of optimization which can only be carried out properly when enough information is available. We would be glad to be able to work further in that direction. 2. We have no experience with the influence of the stiffness of the tool holder on the exit phenomena in milling. From experiments in turning we have some experience with the influence of stiffness of the whole system on tool failure. I must say that influence is quite complicated. In order to explain that we must go back to the basics of foot formation.As soon as the negative shear zone starts the friction force exerted by the chip on the rake face of the tool changes to. the opposite. direction. This causes the tool to be drawn 1nto the workp1ece. When the set up is very flexible this may cause the tool flank to be pressed on to the transient surface. This is turn causes a normal force on the tool flank, which in turn decreases the maximum tensile stresses in the tool wedge. In that case a flexible set up is no disadvantage. In milling the effects of stiffness are not so clear. It should be remembered that due to the flexibility of the set up the actual thickness of cut may be significantly different from the nominal thickn~ss of cut and as was mentioned in the paper the effect of th1ckness of cut is not yet completely understood. Q~~~!lQ~_frQ~_e!?~~~~~Q

Most of the tests were done using carbide inserts and hence it is difficult to generalise for all face milling situations. I would like you to connent on the applicability of your observations in face milling with polycrystalline diamonds (with positive geometry) and silicon nitride (with negative geometry) insert materials. ~~~~~r_fr9~_£!~!~~~_h~I!~B~~h!

I have no personal experience with the application of pce or SiN tools in milling. Therefore my answer can only be a tentative one. Looking back to the basics of foot formation, I would expect that with either the PCD or SiN tools the suddent reduction of the tool-chip-contact-length will also occur with these types of tool materials. I do not know if the inversion of the friction force between chip and rake face would take place and would cause a significant increase of the tensile stresses in the tool close to the rake face which is the main cause of tool fracture. We are now investigating the behaviour of coated carbide tools Which have, as we all know, a lower apparent coefficient of friction at the rake face. The first experiments show that those tools seem to be less sensitive for tool failure due to foot formation. However these experiments have to be confirmed to see if these findings are of more general value. It would be interesting to see if our experiences are also of value when using the more costly tools which you mentioned, but -which for financial reasons- we were not able to test at the University. ~g~~UrQ~_~!~!~~~

We have found a strong correlation between fracture of carbide on exit and the presence of a thin discontinuous built-up-layer (BUL) on the tool face. It appears that upon cooling from high temperature the BUL shrinks more than the underlying tool face. This includes a tensile stress in the tool face which is intensified by the discontinuous BUL. The result is that a region of high tensile stress concentration that causes subsequent fracture that first runs in the "comb crack" direction and then veers towards the clearance surface. I am not suggesting that the explanation of the authors is incorrect, but merely that there may be a competing mechanism that may sometimes be predominant and which may explain some of the result their mechanism wi 11 not explain. 6Q~~~r_frQ~_~!~!_~~~_~~!!~8~~~!

I agree fully with Professor SHAW that there are more mechanisms which may cause cracking of cutting tools. In the past our research grouD made investigations on the formation of comb

664

crack and on the cracking of aluminium oxide ceramics while turning steels. Those results were published in teh Annals of CIRP. We are of the opinion that comb cracks are only dangerous for tool life in situations were also much wl'ar takl's place. In general comb cracks do not ll'ad to what peopll' considl'r to be unpredictable tool failures. Above certain combinations of speed and feed data cracks may be obServI'd aftl'r the first cut in turning. That is a totally different mechanism that we discussed in the present papl'r. In normal turning there is what we called a "soft exit" whereas in milling there is a "hard exit". In turning there will bl' no foot formation. In turning on a bar with a slot thO' foot formation may bl' obsl'rvl'd and this ll'ads to I'arly tool failure similar to the situation in milling. In that case thO' rotation of the chip is hindl'red I'g by filling the slot with plastic you will not find the I'arly tool failurl' but thl'n fatigue failurl' obeying lIeibull's law may be observed. So there may be different arl'as in which different mechanisms apply. I would not dare to say that therl' might be cases di fferl'nt mechani sms interfere with each othl'r. In fact thO' presl'nce of a SUE or BUL has a significant effect on the foot formation and the resulting stressl's on the tool. Th1S has to be taken into account when studying thO' effects of tool gl'ometry, cutting spl'I'd and fl'ed on the tool fracture. III' are trying to penetrate deeper into those aspects right now. PAPER C/15

Page 65 :

C.•. HERTEN, B.F.VON TURKOVICH ·Thermal shock as a carbide grade deve 1opmen t too I" .

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Would you please explain a little bit more about how to measure SIN ? ~~mr_frQ~_£!~!~~~m

SIN (signal to noise ratio) may be viewed as a property of the distribution of interest. The signal is a quantity that characterises the magnitude of the distributed property or equivalently the location of the distribution along the abscissa. Thus a value which remains invariant with respect to the distribution may used as the signal. For the normal distribution this value is usually taken as the mean. For the asymmetrical Weibull distribution, we have chosen the characteristic value. Noise is a quantity which characterises the spread of the distribution or the scatter in data. It is usually taken as some function of the difference between a value which is invariant with respect to the distribution and a value which corresponds to an identifiable point on the distribution curve which is not invariant. For the normal distribution, a measure of the noise is the standard deviation. For the lIeibull distribution, a measure of the noise is the difference between the characteristic value and the value which corresponds to the maximum of the distribution. SIN is merely the signal divided by the noise. It turns out that there is a correspondence between the Weibull shape parameter and the Weibull Signal to noise ratio as defined in the text of the paper. 8~~r~

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Our recent studies at Swedish Institute for metal research on thermal fatigue studies 7 tool carbides do indicate an essential correlation between thermal cycling and bone developement. Question: Have actual milling or intermittend cutting tests been conducted to evaluate the thermal schock influence upon tool performance? ~~~~LfrQl!l_~!~!~~8m

We have not conducted such tests. To my knowledge, actual tests correlating pure thermal shcok or fatigue to actual intermittent cutting performance have not been reported in the literature either. I agree that such tests should be conducted and am of the opinion that they are the only means of establishing a correlation. PAPER CI16

Page 71 :

K.UEHARA, Y.KANDA "Identification of chip formation mechanisms through acoustic emiSSion measurements".

q~~~!!2~_frQl!l_e!~~~~~8!~~~

The power spectrum of the AE signal (Fig.14 and 15) show frequencies up to SOD kHZ. The frequency range in Fig.2 from the audio-recorder is 2-20 kHZ. How was the power spectrum upto 500 kHZ obtained using the FFT analyser? ~Q~~r_fr2!_~~~~~~

The original AE signal has high frequency (ie 100 kHZ ... 114Hz) and we have corrected it to audio frequency using a digital memory technique as is shown in Fig.2. The frequency indicated in figs 14 & 15 shows the original frequency. q~!Hl!!~_frQ'!_~!~~Q!Q~~~m

1. Why did you mount your AE sensor on the tool holder In the feed direction. Do you expect Similar signals if you mount it in the thrust or cutting direction. 2. Have you done system identification to check the courses of force dynamics? You said the dynaMics is related to chip formation. Can you physically explain this for force dynamics while cutting different materials.

~~~~~r_fr2~_~~~~~~~~

1. The horizontal mounting of the sensor is mainly due to the

operational convenience. According to the experiment, there are no significant differences between the signals obtained with horizontal sensor and vertical sensor. 2. In this case, we have limited the scope of the investigation to the wave form of the A[ (sliding at the rake face), and the dynamic behaviour of the whole system is not yet checked. However, it has been confirmed that the naural frequency of the dynamometer is much higher than the frequency of chip segmentation. Q~~giQ~_fr2~_ ~~ ~Q~~Q~~!

1. [xcept for one case where the BU[ formed ended with the machined surface, one A[ signal from the workpiece side did not give any useful date. Does this mean we can ignore A[ signal from workpiece side? 2. You have played the sound generator with sharp and worn tools for different work materials. They sound distinctly different. Can we now take this signal to predict which material we are machining (ie A[ sound and material properties) ?

but the effect is smaller in comparison with upward curling. The only mechanical property of the chip material has been considered is its ultimate strain. We think this is the most important property affecting the chip breakage. Paper C/19

H.WESER, J.HERS[RGER, R.PILZ "Turning of machinable glass ceramics with an ultrasonically vibrated tool".

Page 85 :

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What is the reason why the tool life is improved by applying ultrasonic vibration to the cutting tool 1 ~D~~~r_!rQ~_~~~~~~~

One conceivable reason, to my opinion, is that if the vibration velocity exceeds the cutting speed, the tool momentarily detouches from the chip, and the tool temperature will be lowered as well as for the tool face to be contaminated by air.

~D~~~r_frQ~_~~~~~~~~

1. Concern i ng the da ta wh i ch was used for the ana 1ys i s of segmental chip formation, your opinion is right, however, the workpiece side signal could be used for the identification of workpiece material as is shown in Fig.14. 2. It is necessary to clarify the mechanism of A[ generation to identify the workpiece material. Nowadays we can only recognise the difference of the sounds, then the prediction will be realised if the above problem be solved in the near future.

PAP[R C!17

Page 75 :

H.CHANDRAS[KARAN, S.SV[NSSDN, R.SANOSTROM/V.C.VENKATE5H

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Does the direction of adiabatic shear bands affectcrack propagation during cutting 1 ~~~~~r_frQ~_~~~~~~Q~~~~~~~~

The HHS saw blades made from rolled strips and heat treated to the final hardness in the teeth region did not exhibit any adiabatic bands. PAPER C/1b

Page 81 :

C.Y.JIANG, Y.Z.ZHANG, Z.J.CHI "Experimental research of the chip flow direction and its application to the chip control".

_

Q~~~~lQQ_ frQ~ ~~~~ ~~_~~!I~m~!

I think this is an important paper. The question of chip control has to be solved for all those operations which cause long chips in order to make untented machining possible. That is why we, in Delft, are already workin9 in that field during more than 20 years (with interruptions). Your reference (5) is based essentially on a paper I gave shortly before that keynote paper in CIRP. My experience show that we should be very carefull in formulating laws about chip forms. During my investigations I found out that some work materials behaved closely recording to the Lows of Colding (3), while other work materials behaved more like Spaans observed (4). Still other work materials choose to follow a different pattern. I was not able to find a general law which included the work material properties. Now you present an equation (2) to relate experimentally the chip flow angle with several geometrical quantities. I would expect that the constants and exponents in such relationships would depend en eg work material. However, there seems to be no basic understanding at all why the numbers should be as they are found now. I must say I do not like that kind of equations. Another comment [ would like to make is the following: in free chip formation there are three basic quantities which determine the chip form : chip flow direction, upward curvature and sideward curvature. Especially chip flow direction and sideward curvature seem to be strongly interrelated although nobody seems to be able to find the relationship between the two. As soon as there is any obstacle in the way of the free chip all three quantities will change, mainly due to an innediate change of the shape of the shear surface. This will mean that the assumptions under the heading 3.2. are not valid. In fact I doubt whether any chip breaking model can be based on purely geometric quantities without taken into account any mechanical properties of the heavily deformed chip material. The Importance of that was already shown in reference (4). I am quite willing to penetrate into the subject more deeply. ~~~~r_!r2T_r!~!~~~@

In our paper, equation (2) was obt.ined based upon the experimental data by cutting 45 carbon steel in table 2. This equation has been verified by the experimental data other than those shown in table 2, and also from the data found in fig.S-l0 of the paper given by Spaans (4). This model is also fit to 4OCrNiMo hardened alloy steel which is the one of the type of material usually get unacceptable chips. I agree this model ought to be verified by all different types of materials which will yield long continuous chips. I agree that the chip form will be determined chiefly by chip flow direction, upward curvature and side curvature but I don't see why there should have any correlations between the chip flow direction and sideward curvature. Here we assume that the side curling of chip could be neglected, it does not mean there is not any effect of sideward curvature on chip form

SESSION ON PHYSICAL AND CHEMICAL MACHINING Paper [/2

Page 93 :

M.JENNES, W.DEKEYSER, R.SNOEYS ·Comparison of various approaches to model the thermal load on the EDM-wire electrode"

9~~~!lQ~_fr~_H!~Q~~!~

Do you expect an influence of the loss of wire material due to melting and evaporating effects? ~D~~r_fr~~_8!~~Q~r~

This loss of wire material may be the basic reason why a minimum wire velocity is required. This minimum speed is, indeed, not governed by a thermal overload of the wire when working with very small wire speeds as shown in the paper. g~!H!~~_f~_~!Q~~~m~g

In your photographs of single craters on the surface of the wire there was evidence of cracking. Have you studied the effect of pulse parameters on microcracking of the wire? ~~!~r_fr~_8!_~~Q~!~

The influence of microcracks have been studied In some details for materials such as carbides and hardened steels because it may reduce considerable the ductility properties of various tools produced by EOM-processes. For Cu-alloys as EDM-wire material, the ductily Is much larger and it is assumed that microcracks of the wire observed in the photo's are not significantly reducing the mechanical strength of the wire, 9~!!112~_!r~_t!~~~I~t!~

Did you take into account the heat sinks due to melting and evaporating ? Is the local temperature not a function of the discharge itself, and a higher local temp. can be expected? ~~!~r_fr~_~!_~Q~!~

The energy distribution in EOM r1!tUins an important aspect and has been studied in some detail for die sinking EOM operations. Reference is made to !«lTOKI, to VAN CYCK and to your own doctoral thesis. In the case of the very short pulses (1 ••• 2~s) used in EOM wire cutting some 15 to 20S of the total spark energy is assumed to go to the wire. The remaining energy i~almost

555

entirely dissipated at the workpiece surface as the plasma channel energy can practically be neglected. If the amount of energy losses due to evaporation of material could significantly enhanced this could have some favourable influence upon the maximum temperature in the wire. PAPER E/4

Page 105:

T.MASUZAWA. 1. TSUCHIYA/N.KONOSHITA "Low-energy high current ion source for ion mill ing equipment"

9~~~!12~_fr~_~~~~Q~!~

What are the main parameters governing the magnitude of the error? ~~s~~r_fr~_~!~!~Q~~!!~

At first, it is considered that. the configuration of wiresuspension for example how to guide the electrode-wire, is one of important parameter. Depending upon the designed configuration, both static and dynamic behaviour of the wire are governed. But, the errOr caused by the above mentioned reason is estimated or calculated comparatively easy. if ever the "unknown" force caused by repetiting discharge pulses is correctly estimated. The above mentioned ·unknown" force changes remarkably depending upon the supplied discharge power which has close relation with the wire-feed-rate. Therefore, it is considered that the main parameter of the error is the power supply.

- trimming thin silicon wafers and resistors - machining semi conductors like germanium - inscribing fine reference marks on glass level indicators - etching quartz, saffire and mica - deburring - removing coatings. Of particular interest to this session, is the use of AJM for removing brass plating that occurs when dies are EDM machined. PAPER E/6

Page 113:

B.SCHllMACHER/E.MATTHIAS "Integration of toolmaking into CAD/CAM systems"

9~~~!i2!!_!r2~_~r!~~~Q~§~

Can you tell us of your opinion on the use of expert systems in your studies of computer-aided production planning in [OM? ~!!~~r_!r2'!1_gr!_~~~~~~~~

Figure 2 of the reprint shows for CATD a 1isting of planning/ designing problems and the phrase "forming technology· is related to "expert systems·. Appl icat ing [OM for tool manufacture today runs clearly into problems as standardised and uniform machinability data are missing as well as good working algorithms on the different techniques (planetary. flushing-design. tapes cutting). So I can only support the request on intensified development of data on "expert systems".

9~~~!!2~_fr2~_Q~_Q~~~~

Has the measurement system described been used to correct the path. yet ? ~~~~r_f~~_~!~!~Q~~!!~

Not yet. But it is very easy to apply this system for practical wire-EOM. For considering the application of this measurement system. there are two ways. First. for the purpose of correcting the programmed wire-path. this system is equipped to the conventional wire-EOM-machine. Second. this system is used for making more detailed model of wire-EOM process. Standing upon the model. it is very important to develop or to redesign a new wire-pathcontrol system combined with adequate power supply. g~~~!i2~_fr2~_~r!~£~~Q~~~

What happens to your modelling of the harmonic modes when you use very small wires which are affected much by flushing? ~~~~~r_fr2~_~!~1~Q~~1!~

There is no essential difference between large and small wires. As long as select a well designed flushing system, what affects the wire-vibration is not the flushing but the repetition of discharge pulses which is decided by how to supply the discharge power. 9~e~!j2~_fr~_~!g!g~~~!~f~

A- What is the reason to look for those low acceleration voltages for the ion beam? There could be a high voltage for high current extraction and subsequently an additional deceleration voltage to lower the beam energy. B - What manufacturing methods have been used for the fabrication of the insulator substrate grid. made of 0,2 mm this Alumnasubstrates ? ~~~~r.!r~_~~~~~~~~

A - The reason is simply that the decelaration system is rather difficult for building in to a Kaufman type equipment. However, we are now developing an acceleration-decelaration system for Kaufman type equipment. B - It can be machined with ultrasonic machining method. It ~y be also possible to apply a photo-etching process using "photo form" or "photoceram· produced by Corning Ltd. PAPER [/5

Page lOS:

V.C.VENKATESH ·Parametric studies on abrasive jet machining·

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Cavitation erosion is usually accompanied by a characteristic noise. Could you identify this sound in your tests as a mean of establishing whether cavitation was a factor in your explanat ions for wear.

SESSION ON FORMING PAPER F/5

Page 137

Q~~~!!Q~_fr2~_~!Q~EE!~

You have done some other related work in the area of die forming and we have a somewhat Similar project In mold-making for plastics proceSSing where feedback concepts are used to modify process parameters. Could you comment on the tack-offs between this closed-loop approach and the essentially open-loop approach used in CAD/CAM systems ? ~~~~~r_fr2~_Q~~~~~~Q!

Both are necessary components In an integrated designavel manufacturing operation. The CAD/CAM approach Comes as close to a complete description of tAe part and the manufacturing process as is possible a priori. Process control. using real-time .easureMents. then compensates for any remaining uncertainty when tAe part is actually made. The tackoff occurs when process modelling gets very difficult or idealized whereas the cartoo! can obviate such detail or when process modelling can be quite exact but in-process measurements are impractical or process flexibility does not exist. PAPER F/7

Page 147

~!!~~r.fr2~_~!~!¥~~~!~~~

We are not sure if cavitation erosion occurs as abrasive jet machining is a dry process. The forms of erosion wear do suggest cavitation wear especially when a comparison is made with this aspect of wear in ultrasonic machining which is a wet process. It might be possible that the high humidity in Singapore (95%) contributes to cavitation wear. Your suqqestlon of usinq sound as a mean of identification of cavitation erosion is an excellent one and we shall be pursuinq studies in this direction. 9mHQ!!_fr2'!1_!!~m~~~

What are the main applications of this method? ~!!~~Lfr2!!1_Y!~!Y~~~m~

AJM Is excellent for machininq hard or brittle materials and especially when ultrasonic machininQ is considered too messy because It is a wet process. Some specific appl ications :

666

D.E_HAROT. H.HALE/N.H.COOK ·Closed-loop control of a roll strainghtening process·.

P.HUML/P.O.STRANDEll ·Utilization of flow stress in metal forming calculations".

g~~~!!~~_f~2~_!!!Q~~~~

What do you think about the relation between the behaviour obtained by a hardness test and that obtained by a tensile compressive or combined stress tests? Professor NAKAMURA M•• who was a co-worker. researches this relation and found that In a certain case the hardness of material deformed in reverse direction to the pre-straining increases with increase In accumulated strain. even if In the case of material which shows the Bauschlnger Effect In tension-compression test. ~!!I~fr_frQ~_~!~Y~b

Material deformed successlvelly in reversed direction than In which It has been prestressed. strain hardens

even when the rate of strain hardening can differ from the strain hardening rate observed in monotonically deformed specimens. Consequently, the hardness and flow stress increases. However, if the material -which has been prestrained to a certain strain in one direction- is then repeatedly deformed in at least two opposite directions, the flow stress and even the hardness will decrease (as shown in Fig.2 in my paper and as can be observed during cyclic deformation, see e.g. observations published by STUEWE (J), however only if the prestrain has caused a higher hardness (flow stress) than the hardness (flow stress) corresponding to the cyclic straining. The flow stress (hardness) level during cyclic straining is governed by the strain increment in each strain step and by the number of strain increments until steady-state level of flow stress (hardness) is reaches (see F.G. data published by ARMSTRONG (4). Consequently the hardness in specimens prestrained to lower prestrain as corresponding to the steady-state level of flow stress or hardness, will increase even during repeated straining in opposite directions as prestrain direction. In the contrary, when specimens which have been prestrained to a higher prestrain than such corresponding to a steady state level during cyclic straining (e.g. specimens A4, F3, B2, C2 etc .• in Fig.2 above), the hardness (and flow stress) will decrease, at least for materials investigated in the present work.

hand can make order of magnitude differences in performance. It is by proper choice of grain type possibly in effect, to make chipping wear dominate attritious wear and vice versa. The follow-up comments by Prof. SHAW on the well known and obvious differences between performance of diamond as opposed by cubic boron nitride (CBN) missed my points. There are major differencei in performance whithin the diamond category. These differences will be extremely important in studies involving one of the new challenges and real frontiers in grinding research namely that of high volume removal in high strength structural cera~ics .. I should much appreCiate the author's answer to the l~dlate question but even more to his comments on the broader lssue. ~~~~~!:_f!:Q'E_!!~~mQ

I appreCiate your valu~ble ~uggestions on the importan~e ~f grain type, size and shape, 1n thlS research. Now, we.are thlnk~ng of continuing this work using different types of dlamond gralns: The effect of geometry will be also studied in future. I also thlnk that the bui 1t-up comment by Prof. SHAW is not necessari ly applicable for an explanation of the difference in performance between 0 and CBN grains in this case. £Q~~~_frQ'E_~!£!~~~~

__ ~~~

In complete wheel studies on ceramic materials we have found o to give excellent results whereas ~B~ gives very.p~or results mainly with regard to surface flnlsh and speclflc energy. This suggests that CBN has a greater tendency to form a built-up layer on the grains of CBN than 0 grains. This appears to be the major difference between the performance of CBN and o relative to oxides. This explains our results as well as those of the author both of which indicate a clear message that oxides should be ground with 0 and not CBN. ~~~~~r_f!:Q'E

__ !!~!~~Q

It is variable and interesting information for us that CBN has a greater tendency to form a built-up layer on the grain than o grain. This might be a reason for the poor performance of CBN, as you mention. But, we simply understand for a reason that CBN is too soft to cut ceramics (oxides). 9~~~~iQ~_frQ'E_~~~!!Q~~~~QEE

Dr. MATSUO gave us valuable informations about a test method for grains and about the different wear characteristics of grains under various conditions. As far as the tests are concerned I would like to ask Dr.MATSUO if his method can be correlated to known tests which are used by the abrasive manufacturers like friability test, shock resistance tests a. others.

~~~~U!:Q'E_!~~!~~Q

SESSION ON GRINDING KEYNOTE PAPER Published in this volume J.PETERS "Contribution of CIRP Research to industrial problem in grinding" ~Q~~UrQl!)_8!~~§§

Professor PETERS has made a good pOint about industry not using the information that is already in the literature. I agree. However, it may be that they try to use it and are not able. We should remember that the principles of grinding which we accept today were at first very difficult to understand. HAHN's use of force as an independent variable is an important tool, but difficult to learn. OKAMURA's rubbling/plowing/chipmaking transition theory is not easy to learn. Other grinding knowledge is just as difficult to understand. If this material is difficult and confusing to researchers who have time to study, test and discuss with leading experts, then it may be impossible to understand for engineers in industry who have only a short time to read the words we have written. If we improve the quality and conditions of engineers in industry it will help. If we spend more effort teaching the theory with repetition, simplification, examples and actual application by researchers to solve real industrial problems, it will also help. ~~~~~r_frQ~_~!_~~!~8~

Thanks for the comment. As I said, the scientist is generally not encouraged to present his findings in a relevant manner for scientists ! The requirement to "be original" as claimed even by Conferences for Industry and the stupid use of the "Citation index· are just not encouraging university staff to write for being understood ! Something must be done in this field ! PAPER G/l

Page 185:

T.MATSUO, E.OSHIMA/T.TSUWA "Evaluation of superhard abrasive grains by overcut fly-mi 11 ing test"

g~~H!!!~_frQ'E_e!~!g!~~!m

Could the author please define the type of diamond used in his evaluation of chipping wear and attritious wear in his flymilling tests. It is presently known that the type of diamond (I do not mean simply natural versus synthetic) that is the "friabil ity" and "wearabil ity" (resistance against attritious wear) as influenced by the diamond type on the one hand, and geometriC factors such as size, shape and morphology on the other

Professor TOENSHOFF, you are asking a very important point. We want to investigate in future if this method can be correlated to other abrasive grain testing. But I think that our testing is more suitable for an accurate evaluation of grain friability. g~~~~!Q~_frQ'E_~!_£~~~Q~~~~~~~

1) What is the effect of crystal orientation of diamond upon your chipping test result? 2) Since with each chipping the cutting edge geometry changes how does this influence your results? ~~~~~r_frQ'E_!~~~!~YQ

1) Certainly, the effect of crystal orientation on the chipping test result might be large. The great scattering in the data is considered to be related to the difference in crystal orientation. However, we have used a large number of test grains for suppressing the orientation effect and for obtaining the more practical data. 2) We have no noticeable experience about the influence you suggested. But, we want to investigate the influence of the cutting edge geometry change, as it is important problem. PAPER G/3

Page 193:

R.P. LINDSAY "The effect of contact time on forces, wheelwear rate and G-ratio during internal and external grinding".

Q~~~~!Q~_frQm_~~e~!~8~

1) How do you measure the G-ratio ? I always find it difficult to measure wheelwear ? 2) Why do you, here in America, put so much emphasis upon the G-ratio ? I feel the tool I ife or redress period is more important from economic point of view. The wheel is worn more by dressing than by grinding, at least when made with traditional abrasives. ~~~~r_frQl!)_8~~!b!~Q~~!

1) We grind workpieces narrower than the grinding wheel. After dressing, we place the flat base of a plunger-type dial indicator on the wheel surface and zero the indicator. After grinding, we place the indicator back on the wheel, letting the plunger go into the wear track measuring the depth of wear beneath the reference wheel surface. We take 5 readings around the wheel circumference, and average the values. Our technicians can repeatedly measure 0.0001 inch (0.0025mm). This method eliminates trying to read a micrometer to four decimal places. 2) I agree with your statement. I think many people working in grinding "grew up" hearing G-ratio and, to them, its probably their only "theoretical" knowledge of grinding. Its only historical

557

and can be changed with time and education. PAPER G/4

Page 159 :

C.P. BHATEJA/R.LEVI "Current state of the art of workpiece roundness control in precision centerless grinding" .

g~~~!! 9~ _fr9~ _~~ ~!~Q~~

You have given reference to work published on the "infeed" simu~a­ tion of centreless grinding. For example your reference 4 ~escrl­ bes such a technique. I am pleased to hear that your technlque can be applied to the "through-feed" simulati~n and I,woul~ like to know where information can be found on thlS technlque ~n order,to write an efficient computer program. If you have such lnformatlon or can describe the basis of the procedure it would be valuable as I am carrying out a similar investigation. ~~~~~r_fr9~_~!~~~!~~~

Yes. the technique can indeed be used for through feed systems. The actual software I developed has been used for such systems but is proprietary. The basis is quite simpl~ at least conceptually although it is labrorious and time consumlng. In through- , feed systems due to the tilt of the regulating wheel. the baS1C material removal action at each indexed rotational step of the workpiece being ground. the Gamma Rand Gal11Tl S should be updated to new instantaneous values since at least Gal11Tla R ghanges along the wheelwidth. The final number of work revaluations to terminate the simulation depends on the through feed angle and the regulating wheel speed which can also be input.

9~~~!iQ~_frQ~_~~E!~~~!~~~

1. What is the typical ratio of the dressing diamond roll speed to the grinding wheel speed for a cross axis dresSing set you that you would recommend? 2. Having developed and used a dressing roll and an air jet combination dresser for some time. I have discovered that the stability of the grinding wheel's cutting action is greatly improved by the use of the air jet method as compared with the dressing method. Have the authors' done any grinding to experience the same ~~~~~r_fr9~_;!~~~~; 1. It is nearly impossible to recommend a typical speed

ratio for traverse form dressing operations. Speed ratio and dressing feed should always be adapted to a special grinding problem and may change along the wheel profile. 2. The preparation of CBN and Diamond grinding wheels with jet sharpening lead to very good results during grinding. Especially the transient stage at the beginning of the grinding process short after dressing could be reduced. At the same time the grinding forces were reduced in comparison to conventional sharpening operations.

g~~~!!9~_fr9~_~!~!Y~?~!!~

The effect of machine system dynamic characteristics on the grinding accuracy self-excited chatter vibrations. ~~~~~r_fr9~_~!~~~!~~~

In view of the fact that majority of the application of my simulation was in either hollow. relatively thin parts of smaller solid cylindrical components - conditions for which self-excited chatter is not cOl11TlOn at least in precision grinding operations. Hence my simulation did not account for such vibration. However. it can be done provided some realistic criteria is available for predicting such vibration and a methodology is ava~lable to calculate the frequency and amplitudes which then can be lncorporated in the instantaneous values of the process simulation input variables. gm!iQ~_frQ~_~!_~Q~~!§

- Is this simulation applicable for 2 and 3 dimensional problems (infeed. throughfeed. grinding) - What is the simulation time and the computer capacity?

SESSION ON OPTIMIZATION

~!!~~~r_fr9~_~!~~m~~

- Yes. Indeed the simulation described here is valid for through feed operations. However. to do this. the computer has to calculate the new instantaneous values of the input variables Ganma R. Gar.lllaS. the wheel positions with the vibration amplitude etc •••. - Computer capacity i.e. memory required is about 256 bytes. However. the speed is also quite critical because with a relatively slow computer it can take many hours per simulation. PAPER G/5

Page 205

E.SALJE. H.G.VON MACKENSEN "Dressing of conventional and CBN grinding wheels with diamond form rollers·

g~~~!i9!!_fr9~_~!~!!Q~~?~QEE

Can you apply the nozzle type of sharpening for ceramic bonded BN-wheels too? Is it necessary according to your experience to have sharpening devices if using ceramic bond with BN wheels? ~~~~~r_frQ~_~!?~b~~

KEYNOTE PAPER - Published in this volume G. BOOTHROYD "Use of robots in Assembly Automation" g~~~!lQ!!_frQ~_~~§~§~~~!~~~

Robot application in assembly mostly was considered under economical aspects. Since the figures are rather poor this may be the reason for the conclusion. that the implementation takes place gradually and not suddenly. On the other hand. other aspects must be kept in mind. That are i.e. the aspects of reliability and accuracy. As example in electronics industries some assemblies can be done only by robots due to the achievable high accuracy. ~~~~r_frQ~_§!~QQ!~~QrQ

Yes. I agree. In many situations the increase in reliability and reduction in results and rework due to automation well outweight economic considerations. g~~~HQ!!_frQ~_~!~!QM~~~

Up to now we did not make tests with ceramic bonded BN-wheels but I am sure that the jet sharpening method can also be applied to these wheels if necessary. In some cases it is not necessary to sharpen ceramic BN-wheels if they are for example dressed with a diamond face wheel driven by an air turbine. Jet sharpening should therefore preferabley be used for metal and resinoid bonded wheels.

Criteria for deciding between transfer line assembly and single station assembly in relation to the overall assembly cost?

g~~~!ig!!_frQ~_~!~Q~~!§

Many efforts have been made and are still going on in developing feeders. In future we should concentrate our efforts to avoid feeding. because we get more and more possibilities for that strategy. More flexibility in parts manufacturing permits smaller times and so on. Therefore the investment to keep parts in order is decreasing and let us avoid special feeding devices. What is your opinion ?

There is a steady state condition in sharpening. Going further we loose money. Applying the conrundum stick it is easy to measure forces and to determine this steady state condition. How to consider this in applying the jet? ~!!~~~r_frg~_~!_~~b~~

I agree. If jet sharpening is used for a too long period. not only bond but also grits will be removed and one will loose money. Therefore one has to define maximum sharpening times for different bonds and wheel geometries to make sure that only bond is remo~ed during the jet sharpening operation and the gr1ts remain in the bond during the grinding process.

558

~~m!:_f!:Q~_§!_~QQ!~~Q!Q

I think that my studies show that the major factor in deciding which system is most appropriate is the required assembly rate. g~~~!lQ~_frQ~_tl!~!~~~~~~~~

~~mr_f!:g~_§!~QQ!~~Q!Q

Yes. if at all possible the orientation of the parts should be maintained from manufacture to final assembly. However. manufacturing procedures such as coating or deburring often require the tumbling of parts. In other cases it might simply be uneconomic to provide the necessary magasines.

~~9~l~9~~_g~~~!!9~

Is it more economical to install flexibility into the handling system or into the periphery? ~~~~~r_fr9~_~!_~QQ!~~Qyg·

The objective in a robot assembly system should generally be to keep the assembly cycle time as low as possible. This means minimizing the amount of manipulation performed by the robot. Thus, the need is for part presentat ion methods that completely orient the part and for product and part design to minimize gripper changes and manipulation or reorientation of the assemb ly. g~~~!iQ~_fr2~_~!~~~~~!

It was stressed that reducing the number of parts in assembly is always beneficial. Is it not possible that in order to reduce the number of parts one creates a design of a complicated shape? To machine such a part a great amount of material should be removed in metal cutting. Increasing the number of parts (of such complicated shape) might: 1. save raw material 2. save machining time Is it possible that these savings will be greater than the extra cost of assembly?

PAPER 0/3

Page 283

g~~~!i~~_fr2~_~!~!~~~gy

How do you justify such a system for the 1 or 2 cases where the costs of part programming, changing effectives etc •• will be relatively high? ~~~~~r_fr9~_~!!!~!~~

All of the product design is placed directly with the computer data bank by the engineer. The manufacturing system architecture is designed to directly down load the data into the assembly machines. These machines are scheduled to automatically assemble the computer boards in the quantities required regardless of the quantity. It has been determined that it is not economical to establish a special manual facility and train the supporting personel for very low quantity production. From a practical ~oint of view, the lowest number to be made, because of the extens1ve product system environmental testing required, would be at least four (maybe six). PAPER 0/4

Page 287 :

~~~~~r_fr2~_~!~QQ!~~Qyg

Case studies carried out in industry have all indicated that savings in assembly costs due to product simplification have been accompanied by savings in total part costs. In fact these savings in parts cost usually outweighs the savings in assembly costs. PAPER 0/2

Page 279

D.ZENGER, P.DEWHURST/G.BOOTHROYD "Automatic handl ing of parts for robot assembly" •

R.I.KING, F.B.H.AllDERDICE/R.l.KEGG "Development and performance of an aerospace flexible automated electronic component assembly cell".

G.BOOTHROYD "Economics of general purpose assembly robots"

g~~~!!2~_fr2~_~!~!~~~gy

00 I understand that industrial interest in Robot Assembly is

confined to long run high volume applications and that there is no interest in small batch flexible systems? ~D~~~r_fr~~_g!~QQI~~Qyg

Why is the work of DOlEZAlEK and his collaborators (published in DIN about 1S60) never taken into consideration?

There is great interest in applying assembly automation in batch production. However. it is easier to economically justify automation when the production volume is high. For this reason, robots are being applied under these conditions at present. When programmable parts presentation equipment becomes available and when product design rules have been refixed we shall then see economic applications of robots in batch assembly.

~D~~~r_frQ~_Q.~~~~~~

g~~~! i2~_fr2~_~ !~s§Q~g~! ~ ~

g~~~!!Q~_frQ~_~!~!!~!~~

The authors have not previously been aware of any work by DOlEZAlEK in the area of feeding and orienting of small parts. They are grateful to Prof. MATTHIAS for this reference and they will carry out a full survey of this earlier german work to ascertain its relevance to their present research. Q~~~!!QD_fr2~_~!~!~!~~~~

What percentage of "rea I" parts wi 11 th i s dev i ce feed i. e. how often are parts encountered that tumble. It was not clear how your device could handle a variety of tumbling situations. ~D~~~r_fr2~_Q!~~~~~~

A full classification of parts for this feeder has not been attempted at the present time. However a recent investigation of a family of lock mechanisms for robot assembly, carried out by one of the authors, showed that 40 percent of the parts could be handled with the single sensor belt feeder. Moreover, many of these parts would be impossible to feed and orient with conventional methods. Q~~~!!9D_fr9~_~!~~~~~~~!~

1) Were parts suited for assembly? Were all the products used

in your study suitable for robot assembly? 2) Is "double bind study" needed? To identify group of parts which industry did not present to you but which could be suited to robotic assembly? ~D~~~r_fr2~_§!~QQI~~QYQ 1) The products studied

were those which industries would like to assemble by robot. In fact many were experimenting with robot assembly using these products. This did not mean that the products were suitable. 2) Yes, I think the study should be extended to widen the sample. g~~~!!2~_frQ~_I!~~I~

We expect that the price of robots will come down and that the speed of robot motion will increase very much in future. What kind of influence do these changes give in selecting the type of the assembly system? ~D~~~r_frQ~_g!~QQI~~Qyg

Is the double belt system cheaper than a bowl feeder? Also if you regard the reliability of the quantity of elements within the double belt system?

Any reduction in equipment cost or increase in speed will make robot assembly more attractive economically. However, an increase in robot speed has the greatest effect on economics because this allows more efficient use of the whole assembly system.

~D~~~r_frQ~_Q.~~~g~~

g~~~!i2~_fr2~_~!~!~~~~~~~~

The cost of producing one of the double belt feeders described in the paper is estimated to be approximately *2,500., including the sensor and microprocessor controls. This is approximately the purchase price of a standard bowl feeder. However it is usually estimated that debugging of a bowl feeder system or the assembly machine will approximately double the cost of the feeder. In contrast, the belt feeder is easily adjustable and should incur little extra cost in engineering it as part of an assembly system. The sensor, controls and belt drives have high reliability and give the authors no cause for concern. If the feeder is appl ied to high speed assembly applications then it is felt that a weak link in the system may be the solenoid rejection device. This is an area for further development in order to achieve smooth rejection of non-oriented parts. Q~~~!!9~_fr9~_~!~!~~~QY

What is the changeover time from one job to another on these feeder sys tems ? ~D!~r_frQ~_g!~~~g~~

The changeover procedure from one part to another takes only a few minutes. The feeder can be rapidly emptied by switching off the solenoid and opening the gate at the end of the queueing station. The queue width and control blade position are then adjusted for the new part. A Single key hit puts the microprocessor system in teach mode and the part is simply passed under the sensor in the desired orientation. The system then directly enters run mode and the batch of new parts are emptied into the feeder hopper. Depending upon the difference with the previous part, the sensor position may need altering but this will take only an extra two or three minutes.

1) I wonder how general are the results of Fig. 3 and 4 ? I suppose they are bound to a special example. Would the ratio of equipment investment to yearly operator costs a parameter help to generalize? 2) It was told that in an example the manual assembly takes about 8 sec. and the assembly with a robot about only 3/4 sec. I am astonished about that result because usually the human being is faster in assembling especially small parts.

~~~~~r_frQ~_g!~QQI~~Qyg 1) Yes, the results represent

particular rations of operator and equipment costs. The person interested in using the equations would be required to use figures appropriate to the conditions being studied. 2: It is necessary to realize that in manual bench assembly the assembly time for part includes both part handling and insertion and the handling of any tools (screwdivers etc ••• ) • In robot assembly, the robot simply inserts each part. Magazines or feeders do the work of part presentation. Q~~~!!Q~_frQ~_~!_~~~_~~~~~~b 1) How do you include the cost

of peripheral in your economic study ? 2) How do you decide which peripheral to use for a particular part? ~~~~~r_fr2~_g!~QQI~~QYQ 1) The costs of peripherals for robot assembly are estimated using the best possible information and then used to estimate the total cost of all the equipment in the system. Knowing the assembly cycle time and operator costs, it is then possible to estimate assembly costs.

559

2) At present it is necessary to use judgement as to which peripheral equipment would be required. Because developments are taking place so rapidly it is not yet possible to provide a complete data base for the choice of peripherals.

g~~ ~!! 9~_ fr9~_ ~!~! g~~

Q~~~!iQ~_frQ~_~!_~!!~!~~

The program has not been released commercially. The original intention of developing this program is to allow local industries to have good access to it.

What is the meaning of the constant factor 0.014 in Equ.(2) ?

g~~~!!9~_fr2~_~!~!_Q~Y~!~~

~~~~~r_frQ~_§!~QQ!~~Q!g

It is a combined factor to convert KS to cents and yens to seconds. ~Q~~~!_frQ~_~!~~Y!~

I support Professor BOOTHROYD's figure that there were only 75 robots being used in mechanical assembly in the USA in 1582. PAPER 017

Page

2~9:

S.ZHANG, W.D.GAO/M.E.MERCHANT "TOJICAP - A system of computer aided process planning system for rotational parts".

9~~~!iQ~_frQ~_~!e~~~~~!~

Regarding your plans for the development of the future computer-aided planning and manufacturing programmes, my question is : how many means/hows do you intend to use to solve this huge problems and develop all this software for CAPP/CAM ? ~~~~~r_frQ~_~!~!9~Q

The plan of further development of our CAM system will be carried out only when we would be able to get the financial support of our government. We now must firstly put the developed CAPP system into the practical application at several influential factories. The expected benefits is the only thing that can persuade our government to approve our plan and give us financial support. The plan of our future is very large, but we consider that we would be able to get as more as possible the achievements of our friends in the field of CAP/CAM of advanced developed countries and also different areas in China. At the same time at Tongji University we are now going to organize a special research group to undertake the planned research works. It is possible that in the period of 3/5 years in the areas of the main parts of our plan, effective results will be obtained. PAPER 0/9

Page 307:

Is this optimization program corrmercially available

~~~~~r_frQ~_~!!!~!~~~

W.EVERSHEIM, F.LOCK "Use of multivariate statistical methods for application of group technology in design and process planning departments"

9~~~!iQ~_frQ~_~!~!~~Y!~~

Does the system use standardized fixturing principles (eg positioning, feeding, clamping) and standard components and finally produce a complete design for the fixture? ~~~~~r_frQ~_~!~Y~~~~~I~

Yes, the systems mainly is using standardized principles and elements. But it shows up on the other hand the demands for new or adapted solutions. 9~~~!iQ~_frQ~_~!~!~~~~~~~~

The developed procedure in classifying fixtures gives a good survey about the fixtures available and what are their features. Does it also assist in finding a fixture for a new workpiece to be machined? ~~~~~r_frQ~_~!~Y~~~~~!~

The utilization function for the sample part changes in a cyclic manner. Do you think that this is because of the polygon approximation of circular arcs? ~~~~~r_frQ~_~!Y!~!~~~

The sharp cyclic fluctuation of utilization ratio against angle of tilt arises due partly to the approximation of shape by a number of straight sections and partly to the definition of bridge width, which is the minimum perpendicular distance between any two parts of a polygon. Ideally, a smooth curve should be obta ined. 9~~~!iQ~ _frQ~_~!~!!~m!

You can get the optimum layout of parts. So once you have got the layout, how can you make a linkage to the next stage? For example, how to output the layout drawings? How to get the information for the stamping die? Note that information means dimension data to make a die etc .•• ~~~~~r_frQ~_~!!!~!~~~

The question relates to the second phase of the work that we are doing at present. Once the orientation has been decided, another part of the program (to be developed) shall plot out the exact shape of the drawing (not the approximated polygon) and produce a APT compatible language to drive a CNC wire cut machine for making the die openings. 9~~~!iQ~_frQ~_~!gy~~~~~!~ 1) Is it possible also to

handle different shaped parts with the presented system? For example pairwise stamping? 2) Do you have experience with combined processes, that means stamping, punching and bending? ~~~~~r_frQ~_~!!!~!~~~

1) Generally, it is not a usual practice to stamp our different shapes from a strip of material. The present program can cater for two completely different shapes arranged in a cluster. It is not capable of accommodating more than two different shapes. 2) At present, we are working on a program that develops a stampint into a flat pattern. The developed coordinates can then be used as input data to the existing program. The final program will be able to cater for both stamping and bending operations. g~~~!!Q~_frQ~_~!_~m~~!

To what extent can you comply with constraints imposed by grain orientation ? ~~mr_frQ~_~!!!~!m

One of the input dialogues asks for the bend orientation in a blank. When the user has indicated a bend orientation, the program automatically eliminates the "undesirable" orientations with respect to the rolling direction as indicated in the following sketches

Part drawing

One purpose is retrieval technique for existing fixtures or elements. The other purpose is to create and design new fixtures if possible, using standards. PAPER 0/11

Page 317:

A.Y.C.NEE/V.C.VENKATESH "A heuristic algorithm for optimum layout of metal stamping blanks".

9~~~!iQ~_frQ~_MI~Q~!~Q~~

In practice and especially with coiled material, material cost will vary heavily with coil width and quantity also. Therefore, it often is more economic to use not the highest utilization ratio but instead the solution that will give lowest part cost. Have you considered this problem? ~~~~~r_frQ~_~!!!~!~~~

In the programme developed, the economic considerations have been taken into account although not specifically with reference to cost variation versus coil width. In the programme dialogue, the material cost in $/Kg is one of the required inputs. Therefore, a wider coil will reflect a higher cost in a way. Ideally, narrower coils are more economical as they call for slitting into fewer widths in addition to a lower cost as pointed out by Dr.LINDSTROEM. The programme initially prompts the operator to check if he has stock on hand, if he has, the stock width is keyed in. The layout is now governed by the stock constraint and therefore the highest utilization ratio without constraint may no longer, be selected. If one does not have stock on hand, then the theoretical best utilization ratio will be chosen and a stock purchasing policy will be recommended. The recommended width will be in multiples of slitting widths.

560

H LJ.-J

Re,uired

--"","A"--::",+-...,;~"-;;;:---~::"",-,,,;)~·rection

boo'

of rol ing

A

The orientations correspond to B will be rejected while A will be accepted. If a blank contains several bends, then only the major bend shall be specifiec to avoid elimination of most of the orientations. 9~~~!lQ~_frQ~_~!~~~~~~!~~~~~

How general is the Heuristic algorithm? ~~~~r_frQ~_~!!!~~~~~

The program can cater for any shapes defined by vertices. Several hundred arbitrary shapes were tested and the results so far indicated that the program works in all cases. 9~~~!iQ~_fr~_~!~!Q~Y!~?

How does your system deal with circular parts?

~~~~~r_fr9~_~!Y!~!~SS

Circular parts are the worst shapes in terms of blank nesting. In the present program, a circular part will be approximated by a regular polygon with a representative number of sides (typically 20-30). In a single row layout, the variation of utilization ratio with angle of tilt becomes a constant line. A pairwise layout will have a higher utilization ratio. PAPER 0/12 Page 321:

H.J.WARNECKE, W.DANGELMAIER "Progress in computer aided plant layout"

g~~~!iQ~_frQ~ _~!mB~~s!~

Are the other optimizing goals than transportation minimization within the presented system?

the available computer power may be used in manufacturing not as a tool to speed up the execution of the existing manufacturing system, which lack flexibility but rather to create a new flexible technology. It embraces all activities starting from design and ends in delivery. The philosophy is described in my book "The role of computers in Manufacturing Processes". The application of a philosophy is up to users. As far as I know parts of the philosophy are implemented products based upon HAL-technology. And to the best of my knowledge many graduate students are doing research work on Hal topics. The use of a philosophy is not always (seldom) brought to the attention of the publisher and some time people use its concepts without being aware that they are doing so. g~~~!iQD_frQ~_~r!~~~Y~~Q~Q~~!~

~~mUrQ!rI_~!~!~~B~~m

What is the computing power you need to apply your method? What is the part mixture? We, at M.I.T., are working in the area of integration of Process Planning and scheduling and we found that by using appropriate decision moving rules you can substantially reduce the needed computing power.

g~~~!iQD_frQ~_~!~!Q~Y!S~

The programs are written for Intel 8086 &8087 microprocessors. It will require about 300K Bytes of memory. It is estimated that it will take about 20 seconds. There is no restriction to the number of parts or part mixture as long as the parts can be manufactured by the machines composing the FMS System. We use external optimization results only if they are absolutely correct. ARY decision rule that is only statistically correct is avoided and we compute all alternatives.

No, this programme optimizes in direction of minimal transportation efforts. It tries to achieve a good structure of the organization or lay-out of the plant. Another software package for simulating the operation (bottle necks, queueing used for more fork lifts etc ••• )is needed and available. Does the system produce a complete working plant layout drawing for use on the shop floor? ~o§~~r_frQ~_~!~!~~8~s~~~

Yes, the layout is plotted in a correct scale and permits the installation of the plant equipment accordingly. PAPER 0/13 Page 327 :

M.VERON, P.MARTIN, R.COLLET "Flexible manufacturing of wood pieces for furniture industries".

Q~~~~iQD_frQ~_~!~~§Q~QB!~~

I would find it helpful to hear what sort of furniture is being made? High accuracy and what batch sizes? ~o~~~r_frQ~_~!~~BI!~

Parts of old fashion furniture (Louis XV or Regency style) are made. Cupboards, sideboard, bookcase or table are built with these parts. The part accuracy requisite is low: about 0.2. mm, it is enough because the dimensions of parts can vary with the moisture. With conventional machining, the batch sizes is high (500 to 5000 parts), with the flexible system it can decrease to 50 parts.

~Q~~~r_frQ~_@~~~bgy!

g~~~!iQD_e~_~!~~~~~~IQY

How is it possible to have the tool allocation and the scheduling problem in real time? These are dependent problems, both of which are very complex! ~D~~~r_frQ~_g!_~~~sY!

True, the problems are very complicated, but it is a fact that we are doing it. How? probably by applying the ATO concept, the separation between the real constraints and the artificial ones, we are getting a straight forward logical program. The method by which we do our machine selection in the generative process planning program is exactly the one that we use to compute process alternatives and with no extra effort we use it for scheduling.

~~QD~~Q~~_g~~~!iQD

PAPER 0/16 Page 341

In what sense is it a flexible manufacturing system? Are the machines centrally controlled? Are the parts moved between stations in batches ? Who handles and clamps the parts ?

9~~21iQD_frQ~_~!_~~~~~~IQY

~D~~~r_frQ~_E!~~BI!~

The flexibility is obtained by the numerical control of the spindles positions and the transport systems between them. So, it is very easy to change the type of parts machined, 5m of set time and the batch size can be low. The parts move between stations one by one, not in batches. They are automatically clamped in the front of each spindle, or move between the machines only one operator is necessary to load the system. g~~~~iQD_frQ~_s!~~II~!~~

Why didn't you take into consideration investment cost, direct labor cost. This seems to be necessary for the comparison of the four different systems.

Clarification: are you suggesting that methods of depreciation should be changed internally or that the federal accounting principles should be changed ? ~D~~~r_frQ~_§!§!~~~QY

I am talking about internal accounting procedures. Federal or Governement rules for those purposes and internal rules are different. Often the accounts are different. For instance in the UK, the Governement has allowed new plant to be written off agains too in the first year yet most company accounts will show depreciation on a 10 year straight line basis. It is the internal figures that need to be changed when the company is deciding whether to invest or not. PAPER 0/17

~D~~~r_frQ~_e!~~BI!~

At the present time, it is not possible to know the investment cost. The machine is a prototype, if we consider the studies and the development, its value is very high, if several machines are built, the investment can decrease. The utilization rate of each spindle can give an idea of the investment used. For the furniture bUilder, the high decreaSing of the batch size and the direct labor cost are the biggest interests of the system. Of course, an economical study of the systems will be interesting but it is not possible now to get accurate values. g~~~!iQD_frQ~_~!~!_Q~Y!~~

B.B.HUNDY/J.M.ALEXANDER "Investment in new technology and corporate strategy"

Page 345

J.HATVANY/F.LETTNER "Optimizing the chances of survival

g~~2!iQD_frQ~_~!~~II~!~~

The viability theory needs the definition of a viability space. This needs a method of prediction of this space in time. 8D~~~r_frQ~_~!~~!Y~~Y

The theory is based on the assumption that the only reasonable way to define the viability space is on probabilistiC grounds. These can hopefully be handled as probabilistic sets on the right hand sides of the "differential inclusions".

What arrangements are there for quality control in the line.

g~~~!iQ~_frQ~_~!~g~S~!QY

~D~~~LfrQ~_e~~~B!!~

Does the viability theory contain rules not only on how to stay within the boundary of the viability sphere but also how to expand it ?

The machine described is a first step in automatisation in wood industries. At the present time no control system is set on the line. A manual inspection station is forecasted after the rough planning where the operator chooses the better face. PAPER 0/14 Page 331:

G.HALEVI, R.WEILL "On 1ine schedul ing for flexible manufacturing systems"

Q~~~~1QD_frQ~_~!~!Q~Y!~~

~D~~~r_frQ~_~!~~!Y~~Y

Viability theory has so far not concerned itself with this. However, in the resilience theory framework quite a lot of work has been done on this, and on making survival basin boundaries "softer". There is a track-off between the effort invested in softening or shifting boundaries (e.g. fusion energy research) and the resultant increase in resilience.

Have there been any industrial applications of HAL technology 1 ~n!~~r_frQ~_@!~~b~Y!

HAL technology is a manufacturing philosophy. It believes that

561

SESSION ON DIMENSIONAL METROLOGY IN OUALITY ASSURANCE

applications and the manufacturer may not feel a change is warrented. The customer may have to make the modification himself as we did.

KEYNOTE Paper-Publ ished in this volurre K.LAU, R.J.HOCKEN • Robot 1·1etro logy"

PAPER Q/4

Page 363

Q~~~!i2~_fr2~_8.~~Q~!~

Would it be feasible to use sorre servo accelerorreters with gyroscopes to track the motion of robots? Is the accuracy good enough for this class of problems? ~~~~~r_fr2~_~.~Q£~~~

Current technology is such that the use of accelerorreters or gyroscopes is almost possible. These devices often have drift which must be compensated and the ones that have the required resolution can be quite expensive. It is however well worth the attempt (in my opinion) and I would like to see somebody try it. ~~~!

PAPER 0/1

~~~r~

~Q~~!_~~2~t~~~

It is very important to stress out, that cleaning of the parts to be inspected is important. but very often not done properly. Insofar it i s very interesting to see, that a washer unit is implemented into the presented inspection and selecting system. I recommend. that this should be done much more often in future to follow this example independently from the actual measuring tasks. PAPER 0/5

Page 369

__ fr2~_Q._Q~_~~~

When makin a 3 DOF measurement have 4 or more sensed measurement as a consistency self check in the metrology. Page 347

N.DUFFIE, J.G.BOLLINGER, R.PIPER, M. KRONE BERG "CAD directed inspection and error analysis using surface patch databases."

___ fr2~_~!~~Y~~

Y. I:.AWASAKI, M.SHINODA. S.NOJIRI, A.HAYASHI IT .HOSHI "Deve lopment of a new automatic gear selecting machine for automobile transaxle manufacturing".

E.KOUNOjP.A.McKEOWN "A fast response piezoelectric actuator for servo correction of systematic errors in precision machining".

_

g~~~!! Q~ _! rQ~ ~. ~Qm~

What sensor was used to measure the position of the actuator in order to obtain the performance data presented? ~~~~~r_frQ~_~!~Q~~Q

A Laser Interferometer (Hewlett Packard. USA) was used.

This work is very interesting and valuable. I object, however, to the term "inspection" being associated with the indication of the work on the machine tool which cuts the part. We call this procedure a "part trace". It is a powerful procedure but does not replace inspection because of clamping and machine tool systemtic errors.

g~~~!i2~_frQm_~!~Q~~~~

g~~~!iQ~_frQ~_~!~.@~~~~~~~8~

Thank you for your kind advice. Although the orthogonal stiffness of parallel diaphragms is extr~mely large in the design. I did not measure it. I would like to evaluate it,

I) Isn't it better to use the B-SURF approach because it is ea s ier to mod ify the surface us i ng B-surface ? 2) How do you find the normal to the machined surface in order to digitize the surface using the proble measurement? ~~~~~r_fr2~_~.Q~EE!~

I) We have chosen the Hermite form of defining these surfaces because we wish to modify them in well defined ways such as only in the normal direction. In this case, the defining vectors in the Hermite form can be resolved into appropriate components which can then be modified to change the shape of the surface. 2) We presently use the same predicted normal which is used to direct the probe toward the part. This clearly has drawbacks but suits our needs at present since our major effort now is in developing data base modification techniques. Q~~~!i2~_~~_~.~!~!£~

The plastics parts manufacturer wants to be able to know the shape of the mold to produce particular parts. In order to fill in the data base in the feedback loop from the part of the mold, would it be reasonable to measure an inventory of existing satisfactory parts and corresponding molds thereby obtaining process induced differences. ~~~~r_fr2m_~!Q~EE!~

We do view our system as a source for collecting quantitative data on the effects of plastic properties on final part geometry. A comparison of part geometry with the mold geometry used to make the part could provide valuable information that would be useful in improving and verifying models of plastiCS processes. Variations in plastics properties and changes in parameters in the molding process can also have a large effect on the part geometry produced and these effects could not be ignored in a comparison between mold and part geometry . ~2~~!_fr2~_~!~!!~!~~

to the question from W.B.RICE Our experience is, that the definition of geometry for mold as forging is normally non sufficient. There exists always surface parts that are "thumb-defined" and very difficult to model mathematically. Very often there are crucial surface-parts for the forming process. PAPER Q/2

Page 351

D.B. DeBRA,/J.BRYAN "Design of laminar flow restrictors for damping pneumatic vibration isolators".

9~~~!iQ~_frQm_e!~~~~~8~~

Why does the manufacturer of the isolator not use your laminar flow restrictor ? ~~~~r_fr2m_Q!~!Q~~~~

Twenty years ago, the designers understood the advantage of laminar flow but for the applications for which they were designing an orifice was acceptable. Our new. more demanding requirement came after those designers retired. We all had to learn how the system works allover again. Unless customers request the change, the orifice is adequate for enough current

562

The orthogonal stiffness of the design can limit its usefulness for cutting tests. This would also show up in the higher frequencies of the mechanical elements being close to the desired bandwidth. ~~~~~r_fr2~_~!~Q~~Q

g~~~!i2~_frQm_Q!~~~~

What limits the bandwidth of the feedback loop ~~~~r_frQ~_~!~Q~~Q

Required resolution of the LUDT and maximum current of high voltage amplifier limit the bandwidth. g~~~!iQ~_frQ~_~!e~!~8~

Congratulation for your very nice instrument! But all your tests are made in laboratory. Now with piezoelectric devices the temperature is critical, as you pointed out, what happens with the heat generated by the cutting operation, Can you keep your temperature wi thin 20 · ~ O. SoCwhile cutt ing ? ~~~~r_fr~_~!~Q~Q

Thank you for your kind advice. The heat generated by the cutting operation was not considered in the design stage. A single point diaroond turning machine does not generate heat so much. If a laser interferometer is used instead of LUDT, the influence of the heat becomes small. PAPER 0/7

Page 377

K.TAKESA, H.SATO, Y.TANI/T.SATA "~asurement of diameter using charge coupled device (CCD)"

9~~~!iQ~_fr2m_~!~!!~~!H

Do you use a disposed light source rather than a collimated system to try and avoid diffraction problems? ~~~r_!r~_~!~~!Q

We chose easy method in the laboratory. Apparatus would be required space and accOl1Odatlons around the Nchine tool for collimated light. However, the investigation to adopt this would be worthy identifying the effect of the defraction to this method. 9~~~!!Q~_!rQ~_~!bQ~~~~

Have you considered using telecentric illlclging systems instead of a camera lens? It is more bulky, operates at much higher f number, but makes i .. ging insensitive to focus changes. ~~~LfrQ~_~.~m

Thank you for your suggestion to utilize telecentric imaging systems. At present, I have not. I would like to have the opportunity to apply the systell to the instr~nt. ~~Q~~~u~~H!Q~ It is a very nice instrUllll!nt and quite •• luable work using CCO.

but when used as a di~nsional accurate instr~nt I worry as to the principle Hself. Whenever you il1U111inate an object from the back you sense the shadow of the obj~ct and not the object itself. Furthermore there is an important deffraction effect on the rim. There has been .n Important l1tterature on the subject in the sixties frOll scientist of Znsswerke Oberkochen allOng other frOll! Dr. SCHORSCH.

~~~~~~_f~Q~_~~~~IQ

Thank you for your comments. Some results, rather wide variance around the average, might show the phenomena which you pointed out. However, the instrument practically used which adopts the collimated light is averaging the measured results. This probably aims to avoid the phenomena. Although this was expected before developing this instrument, the objective of the investigation was how to apply CCD to measurement of diameter. The prospect to this objective was obtained by the investigation. I would like to keep notiCing the problem with the reference you raised. PAPER published in this volume J. L. REMMERSWAAL "Our role in the drive to quality assurance" ~Q~~~!_frQ~_g~~~~~§§

I congratulate Mr.REMMERSWAAL on an excellent insight into the causes of low quality. I have never before heard a paper which recognizes the reality of batch manufacturing, that our workers try very hard but the methods and tools which we provide to them do not work. In many cases we are expecting the skills of 1930 which do not exist in the factory today. Therefore manufacturing procedures which require these skills will not be capable of achieving the results which they would have achieved in 1330. The greatest single cause of poor quality is the failure to carry out production engineering activity which will guarantee good quality under current factory conditions.

PAPER 5/3

Page 403

R.BRODMANN, T.GAST, G.THURN IA.WIRTZ "An optical instrument for measuring the surface roughness in production

contro 111. Q~~~!iQ~_f~~~_s~§~I~~~lI~

1. Have any effects due to a distribution of optical properties within the spot image been detected e.g. the effect of grain bounderies ? 2. The measuring range is very large. Would you comment on any restriction on the 2 ~m or so measurement range mentioned in the paper ? ~~~~~r_fr2~_E~~EQ~~~~~

1. The optical roughness value SN is independent of the reflection coefficient of the specimen. This is a consequence of the normalization of the intensity values. The intensity value of each single diode is divided through the sum of all intensity values which leads to the normalized value pi _ JLL. The pi - value is used for the calculation - cli' of the SN-value described in the paper. Therefore the optical properties of the specimen have no influence on the SN-value even if they change within the spot image. 2. The measurement range mentioned in the paper extends to 2~m. This is valid for the measured ground specimen shown in Fig.7. From many investigations of specimens we found however that the measurement range depends on the machining process. For a ground surface where the profile contents a large amount of high spatial frequencies the sensitivity in the upper range decreases to Ra -D.5. Um. Generally one can say that our optical roughness instrument is most suited in the range of Ra = 0.01 ••• 0.2~m. With a weighted evaluation of the straylight distribution we can even measure on optical polished surface with Ra < 0.005 ~m. The limit in the upper range depends on the structure of the profile due to the fact that the SN-value is sensitive ~ot only to the vertical roughness parameters but also to the horizontal parameters. g~~~!i2Q_f~2~_8!~Q~~~~

Do you use a linear Diode Array and if so, then is the value of 5N a function of the angular orientation of the device with respect to the lay of the surface? ~~~~~r_f~Q~_8!~8Q~~~~~

Yes, we do use a linear Diode Array. To determine the roughness perpendicular to the lay of the surface the sensor must be orientated in this direction. Often it is useful to measure the roughness in the direction of the lay e.g. on cold rolled specimens or coarse ground surfaces. Then, the sensor must be orientated in the direction of the lay. So the measurement of the longitudinal roughness is very easy compared to the stylus method.

SESSION ON SURFACES

KEYNOTE PAPER-Publ ished in this volume

Q~~HiQ~_f~Q'.Le~~ !91 ~~1

E.BRINKSMEIER, E.SCHNEIDER, W.A.THEINER H.K.TOENSHDFF "NM destructive Measuring Methods for Eva 1ua t i ng Surface Integrity"

m

What really good methods (high resolution, short time and low cost) have we today for the evaluation of residual stresses as a function of depth in non magnetic, non metallic materials? Does laser speekle interferometry, presently in my opinion still a laboratory tool hold promise in the near future? ~~~~~~_f~Q~_~!~!IQ~~~~Q[[

I would like to make some further remarks: Besides the magnetic and U~ method~ there can be seen other methods based on X-ray techn1ques Wh1Ch could prospectively be used at least after process with sufficient small measuring time and, if necessary, even with the distribution over depth underneath the machined ~urface. Th~ paper gives some informations others will be given 1n the work1ng session of STC "S" by Dr.BRINKSMEIER. PAPER 5/1

Page 393

~Q~~! _frQ~ _8! ~ ~ ~~~~

A.BAR-SHAY, A.BER "Residual stresses in machined surfaces. Elaboration of linear equation and deSign of annular test specimen".

My c~mment is that thin walled rings can be ground without ph~slcally clamping them so that clamping distortions are el1minated. This can be accomplished by grinding the rings freely supp~rted on "shoes" as is corrrnonly done in the antifriction bear1ng industry. ~~~~~r_f~Q~_~!~~8

It i~ quite true, but we did not have this type of equipment and 1t was the easiest way to grind the specimen with the so-called side clamping.

563

CUTTING KEYNOTE PAPER

Pub 1i shed in Volume 33/2 W.KOENIG, R.KOMANDURI, H.K.TOENSHOFF "Machining of Hard Materials"

Q~~~! i Q~_frQ~_ ~ ~~m~~

I like to express my appreciation for this contribution. But I would like to make two comments: a) would it not be good to give more attention to Professor PEKELHARING's theory on the exit angle in interrupted cut? b) It is OK to say "machine stiffness should be higher" but is it not possible to provide quantitative figures using some of the techniques developed in STC "M" ? ~~~~~r_frQ~_~~~Q~~Q~~!

Thank you very much for your kind remarks on our paper. a) As I pointed out in my presentation and discussed in our paper, impact at entry and exit is also important in machining ferrous materials in their hardened condition. A T type contact is preferable as pOinted out in the paper. Professor PEKELHARING work assumes some importance in the case of interrupted cutting. However, the type of chip formation is different for hard materials as compared to soft materials. Consequently, the footforming mechanism at exit is also different. Professor KOENIG, based on his research work feels that exit problem is not as serious in machining ferrous materials in their hardened condition as in their soft condition. b) I agree with you that we should be able to quantify the stiffness of the machine tool system using some of the techniques developed by STC "M", required for machining ferrous materials in their hardened condition. We really should concentrate on the stiffness of the weakest list be it the workpiece, tool holder or the machine tool. In addition to stiffness, precision also becomes important as the tool materials used for machining ferrous materials in their hardened condition are brittle and less forgiving. Since chipping is predominant for the failure of the tool every effort should be made to minimize this mode of tool failure. Qm!iQ~_frQ~_8!~m~~!~

The use of TiC based tools for machining of hardened steel is possible. Especially for finishing operation with small feed rates and depth of cut the use of TiC based tool materials with TiC> 80% and M0 C and Nickel is possible. For example, the machining of SAE 24340 with 55-56 HRc with cutting speeds in the range of Vc • 150 mlMin is possible. The use of Silicon Nitride based materials for hardened cast iron is possible with improved performance compared to Ceramics. Test on cast iron with 75-80 shore (app.600-650 HB) already showed positive results. More developments can be expected within the near future. Talking ~b~ut CBN it migryt be a general question to find out why the mach1n1ng of steel w1th less than 50 HRc is not economical ? ~~~~~r_frQ~_8~~Q~~Q~8!

We agree with your comments on the use of cemented TiC tools for finish machining of ferrous materials in the low range of hardness considered in this paper while it is possible to mach~ne ~ith cemented TiC.tools the authors have not found many appl1cat10~s refer~e~ t~ 1n the.literature. The authors thank you for Su~plY1ng spec1f1c 1nformat10n on this application. Reg~rd1ng why trye.use.of CBN for machining ferrous materials in the1r soft cond1t10n 1S not economical can be realized when one compares the cost of CBN with carbide. So, it is not economically just~fiable to use CBN when other tool materials, such as carb1des and ceramics can be used. Besides the economic reason there ap~e~rs to be a technological reason why CBN is not used' for ~ch1~1ng sof~ ferrous alloys. Rapid crater develops due to chem1:al 1nteract10n betwee~ C~N and a low carbon soft alloy mater1al. In the case of gr1nd1ng, the long stringy chips load the wheel, causing rubbing between the wheel and the workpiece Also, the ~ong st~ings chips dislodges the glits from the • wheel.caus1ng rap1d.wheel wear. It would be nice to report a techn1cal work deal1ng with the machining of soft low carbon steels with CBN tools. Q~~~!iQ~_frQ~_Y.~.Y~~~!~~~

Did you tryout solid TiC (cemented titanium carbide 1) If not, why 1 Sol id TiC with hig Mo 2C might have been able to take a cut. ~~~~r.frQ~_8!~Q~~~Q~8!

We have

not.incl~ded data using cemented TiC tools in my present~tion. It 1s.ma1nly because cemented TiC is generally used at h1gh speed, 11ght cutting of steels in the low end of the hardness scale considered in our paper. We have not found much info~ation of their use for this application by industry. We may 1nclude some data in the final version of our keynote paper.

Qm!iQ~_frQ~_~!~be~~~!~~

far as.stiffness is concerned, in which prinCipal direction 1S the st1ffness of the machine tool the most important 1

~s

~D~~~r_frQ~_8.~Q~~Q~8!

Stiffness in the normal or thrust direction is of primary importance. With round tools stiffness in the radial direction is important. ~Q~~!_frQ~_~.~8~~~8

A comment with regard to Dr.WERTHElM's inquiry regardign the poor performance of CBN tool materials in the machining of soft

564

steels. The real reason for the question is why CBN materials are suitable for machining hard steels. Indeed, if one estimates the wear resistance of CBN as compared to cemented carbide using the criterion of chemical stability that we have developed, no advantage is predicted. In the speed range where carbide is used, no advantage exists and the experimental wear rates are as predicted. However, cemented carbide loses all hot strength on the temperature range from 1100-1200°C whereas CBN maintains hot hardness at much higher temperatures. A critical transition in the boundary conditions between the tool and the chip occurs in the machining of steel in the temperature range of 1200-1300°C. All sliding is eliminated at the interface, a diffusion boundary layer forms in a thin dead layer of workpiece material at the tool surface and wear becomes diffusion limited, accompanied by a drastic decrease in wear rate.This is a completely different wear regime with very important implications for the development of new tool materials for high speed machining (see: B.KRAMER "On Tool Materials for High Speed Machining, Trans ASME) ~~~~~r_frQ~_8!~Q~Q~8!

Thank you for your contribution. We think Dr.WERTHEIM's enquiry regarding technical feasibility of using CBN for machining soft, low carbon alloys still remains unanswered. You mention that using the chemical stability Criterion, no advantage is gained in the wear resistance of CBN compared to Carbide. You also pOint out the reason for this being low hot strength (hardness) of Carbide in the 1100-1200°C region. If this is the only consideration, 1 may point out that it is possible to increase the hot strength of cemented Carbide by decreasing the binder workut by squeezing out the binder under pressure. Using your argument a cemented Carbide produced under high pressure and temperature, similar to the conditions used in the manufacture of CBN tools, should perform better than CBN tools. It is a very interesting argument and it would be interesting to verify it for machining ferrous materials of hardness Rc70, we wonder if hardness of Carbide tools would be adequate? The temperature generated in high speed machining of soft, ferrous alloys would be in the same range as low speed machining of hard ferrous alloys. Harness of the tool material plays an important role in machining ferrous materials of different hardness values. For example we found that Carbide tools can be used up to a hardening Rc58, Ceramics up to a hardness of Rc63 and CBN tools up to a hardness of RC70. Using your argument one should not find any difference between CBN and ceramics tools. We also see rapid crater wear when machining soft, low carbon steel and not when machining hardened alloy steel. Chemical interaction seems to playa part in this case. PAPER C/3

Page 11

A.KINNANDER, I.SVENNINGSSON/B.COLOING "Strategies to control variations in machinabil ity in mixed manufacturing"

g~~~!iQ~_frQ~_~.~~~m

00 you find different conclusions for HHS steel tooling compared to carbide tooling? Prior work by O.LEE and me at FORD (prev~ously employed there) agree with using average optimum relat1ve to a distribution of machinability of real production parts, but for carbide tooling. I believe for HSS, this was not our conclusi~n. This work was written up in a technical paper. I could prov1de the reference to you if you are interested. Answer from A. KI NNANDER ----------------------Since HSS has a smaller value of a (the curve is steeper) than cemented carbide, it will be more sensitive to variations 1n machinability. In practice our strategi 2 could lead to an increase in the frequency of tool failures. This means that the difference between strategi 1 and 2 will be smaller for this tool material, which agrees well with your remark. PAPER E/3

Page 99

G.CHRVSSOLOURIS, M.WOLLOWITZ/N.P.SUH "Electrochemical hole making"

Q~~~!iQ~_frQ~_~r.~~~Q~~~

I do not understand why you chose an electrolyte like sodium chlorate for your hole-drilling when it is so difficult to use in practice. If. as you suggest, an advantage of this electrolyte was the high feedrates that you got, how could you obtain these rates when you quote that the conductivity of the solution was only 0.011 Ohm cm - very weak. ~~~~r_fr~_G.~tl~I~~QLQ~~!~

The choice of NaC103 a~ electrolyte instead of NaN03 is based on the fact that the CIO 3 ion is more "aggressive" than the N03 ion. This leads to a hIgher material removal rate under otherwise the same machining conditions. Furthermore, previous research (reference No.l0 in the paper) has shown that the polarization curve of NaCIO) is, in comparison with the curve of NaNo~ • favorable for the proposed hole making technique. NaCIO, 1S difficult in practice due to its flamability in dry conditions, however one could keep it constantly in water solution so that no fire danger exists. The value of conductivity used in Figure 1 of the paper is not the measured value of the actual electrolyte used in these experiments but an approximate value taken frotll the International Critical Tables for similar electrolyte conditions. It may be lower than the conductivity of the actual electrolyte; however this does not affect the validity of the side wall maChining model.

g~~ ~ ~ lQ~ _frQ~ _~! ~Q~~! §

PAPER 0/8

What is the l/d ratio you want to have applied for the technique described ? Are there any experiments comparing your technique and STEM? ~~~~r_fr2~_§!~~~Y~~Q~Q~~!~

The maximum ration l/d we have applied this technique is 1:10. An experimental comparison between this technique and STEM on the same workpiece material has shown very rough surfaces and occasionally microcracks on the wall of the holes produced with STEM. PAPER Gil

Page 217

Y.TANI, K.KAWATA/K.NAKAYAMA "Development of high-efficient fine finishing process using magnetic fluid" .

_

g~~~ ~1 Q~ frQ~ J;!~! Q~~~~ ~

What is the size of the ferrite particles in the magnetic fluid? What is the vol. or wt % of ferrite in the fluid? Does any manufacturer of plastic lenses presently use this process ? ~~~~r_!r2~_Y!I~~!

The ferrite particles in the magnetic fluid have the diameter of about 10/15 mm as shown in the paper. And that fluid we used, contains the ferrite particles of 40wt%. The number of magnetic fluids' name in Table 3 means that concentration ratio. Any manufacturer including that of plastic lenses doesn't use this process yet. The investigation of this process has just started. The application to industry is a future problem. PAPER G/8

Page 218

M.C.SHAW "Surface melting in grinding operations ?"

Page 303

B.J.DAVIES, I.L.DARBYSHIRE "The use of expert systems in processplanning"

~~Q~l~~~_9~~~~lQ~

Is the system giving one or more solutions according to some performance index ?

~~~~~r_!rQ~_~!~!Q~Y!~~

The system will produce from 1 to 50 solutions under control of the operator who uses various strategies to reduce the search space. For each solution a confidence level and an estimation of the processing time is given. The operator can overide the system selection at any deceision node when the system will show him all possible next options. ~Q~~~_!rQ~_~!~!!~!~~

I see some danger in the use of the system you describe. because it will always choose a "medium" solution. while we need progressive productivity. ~~~~!1r_!rQ~_~!~!Q~Y!~~

The system is capable of defining all solutions which depending to the objective function, must include the optimum. For each solution the system gives a confidence level and a processing time. If the knowledge base is good enough the system will select its best solution. The knowledge base can be built up from many experts. Already for restricted area mediacal diagnosis expert systems out-perform the average speCialist. 9~~~~iQ~_frQ~_~r!~~~

Do you think, while using this generative approach, that it will be possible to investigate and evaluate the influence of the use of different tools independently. The same question is raised with respect to clamping. ~~~~r_!rQ~_~!~!Q~Y!~~

What depth of layer has to be transformed for you to consider that melting has occured ?

It has been suggested by expert systems speCialists that machine tool, and fixture selection. It seems to me that expert systems are well suited to this areas of complex decision making.

~~~~~r_frQ~_~!~!~~~~

PAPER 0/15

Q~~~~iQ~_frQ~_~!~!~Q~~

In this tudy fine grinding was considered where the peak to valley distance of grinding is of the order of lum. For leveling of the surface it was considered that a minimum thickness of 1 um would have to melt.

Does your analYSis hold for vertical spindle surface grinding ~~mUrQ~_~!~!~~~~

Yes, it applies. However in the example fine grinding was considered since in vertical spindle surface grinding and other abrasive machining operations the peak-to-valley roughness will be greater, the depth of layer to be leveled by surface melting will be greater and hence the time required for melting will be greater than for fine grinding. Page 295 :

K.IWATA, F.OBA, K.YASUDA "Simulation for design and operation of manufacturing systems"

9~~~~iQ~_frQ~_~!~~8~~~!Q¥

1. Why was the simulator developed? To let people with no knowledge of simulation use it ? 2. What real advantage is there with graphic animation?

9~~~ ~ 1Q~ _ frQ~_~! ~~ m~

PAPER 0/6

Page 335 :

T.KOJIMA, H.SEKIGUCHI, K. INOUE , T.HONDA, K.MISUE/H.TAKEYAMA "Development of machine part data model consistent with designer's shape description in CAD/CAM system"

9~~~HQ~_frQ~_g!~Q~~m~~

What type of user dialogue are you using? Are you for example using CRT where you can see the models and are you using menue-technique ? ~~~~!1UrQ~_!!~Q~!~

At present user's command of text from keyboard is utilized. Q~!1~~jQ~_frQ~_~!~Y~B~~~!~

Is the presented system still under development, or is it in use in industry ? ~~~~~r_frQ~_!!~Q~!~

The project concerning with the system is still undergoing and it is not in use in industry. Q~~~~lQ~_fr~_~!~~~~~8!~~~~~

Did you use any commercial data base management system for representing the data model? ~~~~r_fr~_!!~Q~!~

No we didn't use any data base management system. Data were stored in files.

~~~~r_frQ~_~!!~~!~

1. When we develop a manufacturing system, we would like to evaluate the system characteristics, such as flexibility and availability, in the design stage previously. If the system is relatively small and simple, we can apply the analytical methodology to the evaluation of system. However, the system becomes relatively large and compl icate, we cannot use the analytical method any more. The useful method at present is to use the simulation. The simulation technique can be as a useful tool when newly designing an effective and economic manufacturing system as well as effectively operating the installed manufacturing system. This is the main reason why we have developed the simulator based on the design concept mentioned in the paper. This simulator enables users with no knowledge of simulation to eas ily use. 2. The real advantage of graphic animation is mainly that the user can easily and visually understand the simulation process step by step, and continuously s-e the dynamic behaviour of manufacturing system under stay. PAPER Pub Ii shed in Volume 33/2 J. L. REMMERSWAAL STC "Q" "Our role in the drive for Qual ity Assurance" ~Q~~~_frQ~_~!~!~!~~!~~Qb~

I think that as the STC President you are to be congratulated for arranging for this paper to be presented at the STC "Q" paper session. The paer deals with a subject which a recent survey by INSEAD of European companies has shown to be among their highest corporate priorities. The subject is therefore of very great industrial importance in the whole field of manufacturing technology; yet it is a subject which seems to have received little explicit consideration within CIRP. I hope that the presentation of this paper will lead now to firm proposals for the future study of this subject in CIRP and on how this should be organised.

Q~!1~~lQ~_frQ~_~r!~~~

Which semantic checker did you apply ~~~~r_frQ~_!!~Q~!~~

Geometric checks as to regular 3D object are included to some extent. We found the complete check of the constraint was quite difficult in the course of study.

565

PAPER C/13

Page 55

P.K.VENUVINOD, W.S.LAU, C.RUBENSTEIN "Analysis of the life of controlled contact tools via flank contact temperature estimation"

units you proposed? ~~~~~r_frQ~_~~~!Q~~~~~

If necessary a passive angular alignment unit is added. PAPER 0/&

Page 303

g~~~!iQUrQ!!I-I~~m

Have you measured the normal stress, the shear stress acting on the flank face of a cutting tool and compared these with those on the rake face of the cutting tool ? Have you also measured the temperature at the flank face of the cutting tool ? I have a different understanding on the fricition on the flank face of the tool. According to Professor USUI's research, the contact between the flank face of the cutting tool and the machined surface is not continuous but interrupted. During the interrupted period of contact, the flank face of the cutting tool is cooled to give the flank face temperature lower than that at the rake face. ~~~~~r_!rQ~_~~~!~~~~Y!~QQ

The forces acting over the flank land area were determined from the slopes of Fc versus If and Fv versus If lines (7). Analysis of empirical data obtained while machining mild steel with H.S.S. tools shows that the mean apparent normal stress at the chip-tool interface is about 1.S times that at the flank contact surface whereas the mean apparent tangential stress at the chip-tool interface is 1.5 times that at the flank contact area. The alternative view of flank contact conditions suggested by Professor USUI 's research is interesting. I,e thank Professor SATA for bringing this to attention. Apparently, Professor USUI's researches suggest that flank contact is continuous in space but discrete in time (i.e.interrupted) whereas our idealisation implies that flank contact is continuous in time but discrete in space; consider now the implications of these two viewpoints. It was shown in (7) that the application of Chero and Trigger's analysis (an analysis based on the assumption that flank contact is continuous in space as well as in time) results in flank temperature estimates which are "too low" in comparison with what one would expect from machining data obtained when H.S.S. tools were about to burn-out. It does not need much analysis to appreciate that flank temperature estimates would be much lower if we assume that flank contact is discrete in time (i.e. interrupted). On the contrary, our view that flank contact is discrete in space (but not in time) results in higher flank temperature estimates. Mean flank spot temperature (efs) can then be made higher than the mean rake temperature (~r) by a suitable choice of N, which is consistent with the empirical observation that H.S.S. tools tend to burn-out at the flank and not at the rake face. Q~~~!i~~_!rQ~_~~br2~_~~~~~~I!

The model that you presented addresses only the heat generation mechanisms on the flank face. There are other mechanisms, such as rubbing on the rake face. Also there are temperature distribution throughout the tool, which require that "flank temperature" etc ••• be precisely defined. Is there a general understanding of how to model all these phenomena, and how to co-lect reliable data for comparison and validation of models? ~!m!!1r_frQJ!I_~!~!YmmQQ

Our model takes into account the heat generated at the rake face as well as the thermal interaction between the rake and flank heat sources due to heat conduction within the tool. It thus considers all the mechanisms mentioned by the writer and attempts to develop a general understanding of all these phenomena. Our model is validated by tool life data. Q~~~!iQ~_frQJ!I_~!~Q~~~QY~!

Have you varied the clearance angle? If so, what effect this has on the flank temperature and your model ? ~~~~~r_frQ~_~!~!Y~~YY!~QQ

Yes. We have checked the model against tool life data obtained at different clearance angles. Temperature afs is independent of clearance angle (since we idealised the tool as a quarter-infinite conducting medium and we ignored the small amount of heat generated due to contact at the clearance face resulting from the elastic recovery of the workpiece). Thus the clearance angle influences tool life only through constant K4 (see equations 10 and 11). PAPER 0/5

Page 2; 1

P.J .DRAZAN, S.H. HOPKINS/R. TILSLEY "Semi autonomous systems for automatic assembly·

Q~~~!iQ~_frQ~_~!~~~~~~!~

Did you determine the transient of the pneumatic dynamometer and how fast the response of the control actuator is in this case ? ~~~~~r_frQ~_~!~!Q~~~~~

The pneumatic adaptable unit's time constant is .3 of a second. This value has been measured on the prototype and is antiCipated to be reduced on the production unit. Q~~~!iQ~_frQJ!l_~!Y~~_~~Y~§~~

How do you cope with angular misalignments with the different

566

B.J.DAVIEc, I.L.DARBYSHIRE "The use of expert systems in process planning"

g~!1~!iQ~_!~Q~~~~!~~!~~

Please describe your choice of AI language for EXCAP. ~~~~~~_frQ~_~~~!Q~Y!~§

The language used for EXCAP is a derivative of the AL/X language mentioned in the paper. It was felt that many of the facilities offered by "conventional" AI languages (PROLOG LISP, SASL etc ••• ) were unnecessary for this application, and would slow the system down too much. There is also the problem of interfacing these languages with PASCAL which forms the "front end" of the system. AI languages are notoriously difficult to use for prograll1l1ing reasonably friendly user interfaces. The rules are originally written on a conventional text file, and this is then input to an EXCAP module which checks these rules for syntax and semantics (searching for coops in the reference network). This module then generates a file of PASCAL records representing the network. This file is used as input for the planning module, which can rapidly re-constitute a representation of the network in memory. Having done this, it is a simple matter to provide PASCAL routines to infer conclusions from these rules, and it would also be possible to change the rules dynamically by alteration of the links within the network. Each node of the network is represented by a single PASCAL RECORD, and is aSSigned a name. Tracing the flow of reasoning is therefore a simple matter of printing the names of the nodes as they are used. Q~~~~i2~_!rQJ!l_!!~Q~~

How complex a part geometry does your system support. Specifically can the part have inside geometry. Also, is your expert system able to explain to the user the rules used to arrive at conclusions. ~~~~r_!rQ~_~!~!Q~Y!~S

1. Complexity of EXCAP parts. EXCAP is a modular system. The planning module is currently capable of dealing only with an extremely limited range of parts. The geometric ~efinition module, however, is capable of defining any turned component, both externally and internally, including radii, chamfers. knurls, threads etc .• It will be some time before the planning module catches up, but this is the ultimate intention. 2. Explanation of rules used. EXCAP stores planning rules as a direct internal representation of the inference network, in exactly the same way as the AL/X system mentioned in the paper. "Facts" and "hypotheses" are represented by nodes in this network, and are stored as PASCAL RECORDS. Each of these records has an associated name and explanatory text. Explaining the rules used to arrive at conclusions is then Simply a matter of printing the names and/or explanatory text of the nodes as they are used. This is how the explanation facility is currently implemented on EXCAP. It is a fairly trivial exercise to re-write this information as conventional "IF-THEN-ELSE" rules, but this has not been done so far. Q~~~!iQ~_f~2~_~~~!~~!~QY!~~

Have you considered the fixturing of the part in your analysis. This can greatly influence which branch of the decision tree will be followed. The fixturing itself in turn may be influenced by the required paralellism of individual surfaces in case of rotational parts. ~~~~!1~_!rQ~_~~~!Q~Y!~~

Importance of fixturing : currently , EXCAP takes no account of fixturing, and somewhat simple-mindedly assumes parts to be chucked at one end and free at the other. We agree that the fixturing problem is of very great importance, and must be tackled if EXCAP is to produce reasonable plans. The fixturing is itself at least partly determined by the choice of machine ; the machine de~ds on the dimensions of the component, and the accuracy and power required; the accuracy and power are influenced by the fixutring used. This looping is an over-simplification, but seems to suggest some level of iterative approach to machine and fixture selection. g~!1~!iQ~_frQJ!l_~r!~~_§~QY~

In your opinion , how widely do you think that Prolog can be used in expert systems for machining processes. ~~~~r_frQ!_~!~!Q~¥!~~

Importance of PROLOG in Expert Systems for Machining Processes : The decision-making lllechaniSlll used by EXCAP requires that a large number of decisions be made fairly quickly. These decisions usually, ultilllc1tely break down to Simple c~risons between numeric quantities, for which PROLOG is quite deliberately not designed. PROLOG can be made to cope with floating-point numeric quantities, but this would seetl to 11M! to be forcing a quart into a pint pot. Where I problem is involved with less

tangible properties than depths-of-cut. material hardness etc ••• lam sure PROLOG is ideal. For EXCAP, and, I suspect, other similar systems. it is just too complex. EXCAP is written exclusively in PASCAL ; rules are stored interna lly as a network of PASCAL records. Apart from a few hardware dependent facilities, principally I/O, EXCAP should be transferrable to any other machine running PASCAL. The same could not be said if EXCAP were a hybrid system of PASCAL and PROLOG. or even if it were written solely PROLOG. gY!U.12!!_!r2!!)_~~B~_~Lm~~

The structure of the diagram for the algorithm looks like that of dynamic progranvning. Does that limit the complexibil ity of parts to avoid the "curse of dimensionality" ? Also, what is the "confidence level" ? ~!!!~!!:_f!:QI]_~~~~g~~!~§

1. Limit of part complexity.

Although the structure of the EXCAP algorithm does look like that of dynamic programming, in practice only a portion of the decision tree is ever retained. The purpose of the planning rules is to eliminate as far as possible, those branches of the tree which are not expected to lead to a good sequence. Back-tracking through the tree may require previously discarded branches to be regenerated, but in the context of a system which is repeatedly generating and discarding such branches, this does not constitute an appreciable overhead. The number of branches at each node which are retained is under the control of the user, by default the system retains only one branch at each node. Thus the complexity of the part, and hence the size of the generated sequence tree, is limited only by the memory available. This presents no problems on a VAX with 1.5 MIl of virtual address space. 2. ·Confidence level". The confidence level is the ultimate output from the planning rules, and is measure of confidence in the hypothesis that a particular operation is suitable for selection at a particular point in the sequence tree. The confidence in the sequence as a whole is taken to be minimum of the confidence values of the operations it comprises. This is an over-simplification, since it provides no means of comparison between two sequences which have the same worst operations. STC "Q" KEYNOTE PAPER

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Published in th1s volume J.PETERS "Contribution of CIRP Research to Industrial Problem in Grinding".

The tendency goes more and more to the grinding of hard materials as Al203i Si3N4i SiC. Those materials will bring up aga1n more the problem of the actual machining t1me and therefore more emphasis should be given to the process than to organisational problems. a~!~!r_fr2!!)_~~ft!~8~

Thank You. I agree

gY!!~12n_!!:2m_B~~Q~~~QYB!

Professor PETERS, You have presented a very stimulating paper. My quest10ns are: 1. Do you think industry will aq~ip grinding machines with the types of sensors you mentioned in your paper. The user may not recognize the l~portance of this. How can we influence the 9rin~ing machlne manufacturers to incorporate sensors not as opt10n but as required as we know that senSOrS are essential for successful 1 grinding. 2. Do yoU think industry will standardize grinding wheels so that thera won't be much variability in performance ? aD!~!r_fr2!!)_~£e~I~B~

1. The customer is king. The machinas will be equipped with the appropriate sensors whan the user will fael it profitable, because of the increased quality required or because of the need to use automat~c machines with adaptive control. It may well ba that other aspects of the manufacturing process are felt more imj)ortant e.g. CAD, CAM etc ... 2. Standardisation is possible today, the factors to be taken into account are well known. ProfessorSNOEYS Droposed a very logical gradation system fop the -Grade i • The onl, question ls the wll1 of tha manufacture.s in the cOlunlrclal competition.

PAPER G/2

Page 189

R.S.HAHN : "On the universal process parameters governing the mutual machining of workpiece and wheel applied to the creep-feed grinding process".

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Could you explain how you measure your Metal removal Parameter on the machine for Adaptive Control as you mentioned. ~D!~!!:_!r2!!)_8~~&~~~~

The 'force adaptive grinding control" drives the cross slide at a certain feed rate if 1 and measures the corresponding force Fnl ' It then substracts the Threshold Force. The work Removal Parameter is then : WRP

Ow if! Fnl - Fth

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I am very encouraged by the contributions of our invited speakers. They have made. a number of very relevant and valuable comments about our proposed CIRP research programme which I think we must study carefully and take fully into account in planning our research. I believe that all the work which we did in preparing for the discussion at Harrogate at the IS83 General Assembly, and our work subsequently in reporting the discussion and developing our research proposals (all of which is described in my report) have been well worthwhile since it has paved the way for these critical evaluations of our proposed research and placed us in a pOSition to profit from them. In effect, we can almost afford to "throwaway· the report as it stands and start afresh now to reconsider the precise nature of our proposed research in the light of the detailed comments which our invited speakers have made. More generally, this afternoon's experience is an example of how CIRP's work can benefit from working co-operatively with distinguished persons from related disciplines.