- Email: [email protected]
In-process tool-failure detection of a coated grooved tool in turning
Journal of Materials Processing Technology 89±90 (1999) 287±291
In-process tool-failure detection of a coated grooved tool in turning K.S. Lee*, K.H.W. Seah, Y.S. Wong, Lenny K.S. Lim Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore
Abstract With the increasing use of computer numerical control, there is a growing need to ensure a reliable system to optimise tool usage or tool wear. This paper presents a study on the fool failure of a coated grooved tool by monitoring the tool wear indirectly using the dynamic component of the tangential cutting force, Ft. Experiments conducted on AISI 4340 (ASSAB 705) and AISI 1148 (ASSAB 760) steels using a CNC lathe have revealed that there is a good correlation between the dynamic tangential cutting force and the ¯ank wear of the tool. The natural frequency of the recorded dynamic force corresponds to the natural frequency of the tool. The results indicated a trend for Ft, which starts at a low value and ¯uctuates about this level during the normal wear stage. As VBmax increases to about 0.4 mm, the force increases rapidly in a non-linear fashion until the tool fails. Statistical analysis using a t-distribution test has showed that the dynamic tangential force gave a promising threshold value for the prediction for AISI 4340 and AISI 1148 steel. On-line tool-wear monitoring software was used to track the dynamic force signals to predict the possible onset of tool failure. # 1999 Elsevier Science S.A. All rights reserved. Keywords: Tool-wear monitoring; Tool-failure detection
1. Introduction To realise the full potential of unmanned machining, the on-line identi®cation of the state of the cutting process and the detection of impending failure of the tool is mandatory. A tool is considered to have failed when it experiences excessive wear or premature tool fracture. Machining with a failed tool results in the deterioration of workpiece quality such as dimensional accuracy and surface roughness as well as the possibility of damaging the machine tool. A cutting tool may reach the end of its useful life due to excessive wear or premature tool breakage [1,2]. Machining with a blunt or broken tool can cause the workpiece quality to deteriorate and possible damage to the machine tool. Therefore, a reliable tool-wear monitoring technique is important in an unmanned machining situation to avoid such a catastrophe and allows optimum utilisation of the tool life, which is highly desirable. Several surveys and comparative studies on the methods of monitoring tool wear have been carried out [3±5]. Generally, the methods of monitoring tool wear can be categorised into direct and indirect approaches. The direct methods measure the ¯ank and crater wear of a cutting tool directly, using e.g., touch trigger probes, optical devices and *Corresponding author. E-mail: [email protected]
electrical resistance techniques. These methods are dif®cult to employ on-line because the sensors have to be in close proximity to the tool tip where wear or breakage takes place. The sensors are apt prone to being damaged in this situation. Furthermore, the detection of premature cutting edge failure is not possible whilst the tool is cutting. The indirect methods involve the measurement of cutting parameters, e.g. cutting temperature, cutting force, vibration and acoustic emission. These methods are more suitable for on-line monitoring as they allow uninterrupted machining to take place and eliminate problems that occur when using the direct methods. In a previous study [6,7], it was determined that the dynamic cutting force has a good correlation with the ¯ank wear of the tool. A number of studies have also found the measurement of the dynamic force to be effective in monitoring the tool wear [8±10]. Lay et al. [11] reported that the detection of ¯ank wear was possible by monitoring the dynamic force at a particular frequency. The ratio of the increment of the dynamic component to the static component is signi®cantly higher, roughly between 75% and 480%, for a ¯ank wear width of 0.2 mm. The measuring of the dynamic force produces a reasonable indication of tool wear and offers a reasonable speed of response. The present study investigates the use of a personal computer to perform the on-line tool-failure detection of
0924-0136/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved. PII: S 0 9 2 4 - 0 1 3 6 ( 9 9 ) 0 0 1 3 8 - 7
288
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291
area having a point load at the end. The resonant frequency can be calculated by means of the following equation: r kn 2 EIX fn Hz: 2 ml4
Fig. 1. Experimental set-up for tool-wear monitoring.
groove tool in turning. Software was used to track the dynamic force signals that correlate well with tool wear. 2. Experimental Fig. 1 shows the experimental set-up for the tool-wear monitoring. Experiments were conducted on an OKUMA CNC lathe. The workpiece materials used were AISI 4340 (ASSAB 705) and AISI 1148 (ASSAB 760) steel. The cutting inserts used were coated and grooved Sandvik SNMG120408 PM inserts, which were ®xed onto a Sandvik SBTR-16-4 R174.1-2525-12 tool holder, having a tool signature 58, 68, 58, 68, 158, 158 and r0.8 mm. The cutting forces were measured by a Kistler piezo-electric dynamometer TYPE 9123. A 25 MHz 486 personal computer equipped with a fast Fourier transform (FFT) card recorded the dynamic force signals. The FFT card is a model 25 digital signal processor board based on the Texas Instruments TMS320C25. The ¯ank wear of the tool was measured by means of a toolmaker's microscope. 3. Operating principle of the on-line sensor The dynamic forces generated in metal cutting can be attributed to many causes, the most predominant amongst which are the oscillation of the cutting tool, the shearing action of the chip, the uneven surface and the non-homogeneity of the workpiece. The force signals can be measured by the dynamometer holding the tool. Lay et al. [11] have investigated the dynamic cutting force and found that more meaningful results can be derived when the dynamic force is presented in the frequency spectrum. A prominent peak was observed in the frequency spectrum that remained substantially constant throughout the life of the cutting tool. The origin of the peak frequency was found to be related to the resonant frequency of the tool holder [10]. The resonant frequency of the tool holder can be represented by a simple cantilever beam with a uniform cross-sectional
There are four modes of vibration for a simple cantilever beam. Rao [8] has veri®ed that the ®rst mode usually dominates as the tool wears. It can be deduced that when machining with a new cutting tool, the dynamic force is small because of minimum rubbing contact between the tool and the workpiece. As the ¯ank wear-land develops during machining, the rubbing contact between the tool and the workpiece increases, resulting in the increase in the dynamic force amplitude. On approaching the end of the tool life, there is severe thermal weakening at the edge of the cutting tool, and the tool begins to wear off at a faster rate. The blunt tool causes an additional heat source as it rubs against the workpiece. This further weakens the tool and plastic collapse occurs subsequently. This is one wear mechanism that affects the tool life, as identi®ed by Wright [2]. Since the dynamic force was observed to have a good correlation with the tool wear, it is possible to use a personal computer to monitor the dymamic force during machining. A software program developed by Lee et al. [12] was used to monitor the dynamic force of the grooved tool. A personal computer equipped with a fast Fourier transform card was used to perform the necessary data acquisition and FFT processing. The FFT PROCESS subroutine processes the digital signals into a frequency spectrum. The signals are the averages of every 128 frames of measurement to smoothen out any ¯uctuations. The software developed so far allows for continuous monitoring of tool wear or intermittent stoppages and monitoring. Statistical analysis of the experimental results revealed that it is possible to set a threshold value for the percentage increase in dynamic tangential force, Ft, to predict tool failure with 99% con®dence level. 4. Results and discussion A comprehensive study has shown that both the feed and tangential component of the dynamic force correlates well with the tool ¯ank wear. Experimental results reported earlier [6,7] show that the absolute value of the dynamic force bears little relationship to the magnitude of the tool wear. However, a good relationship is found to exist between the trend of the dynamic force and the ¯ank wear. Fig. 2 shows the dynamic tangential force and the maximum ¯ank wear of the grooved tool for AISI 4340 (ASSAB 705) steel. Generally, the dynamic tangential force Ft ¯uctuates about a mean value as the cutting proceeds, this continuing until the ¯ank wear reaches approximately 0.4 mm, which is followed immediately by rapid increase in the value of Ft. The trend of the dynamic tangential force
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291
289
Fig. 2. Illustration of the dynamic tangential force (thick line) and flank wear (thin line) for AISI 4340 steel.
observed is in contrast to that of an ungrooved tool, which exhibits a monotonic increase followed by a fall towards the end of the tool life [12]. It was also noted that during cutting, the dynamic tangential force was low (in the region of 10± 35 N). This can be attributed to the grooved nature of the tool (SNMG120408 PM), which offers a higher normal rake angle as compared to that of an ungrooved tool. The trend of the dynamic tangential force observed can be explained by considering two factors: the increase in contact surface area between the tool and the workpiece, and the temperature at the tool±workpiece interface. During the initial stage of cutting, the ¯ank face experiences normal wear as a result of rubbing between the tool and the workpiece, which grows slowly. On approaching tool failure, the wear land would have increased many times over. This causes weakening of the cutting edge. Since a weakened edge will deform and recede, more rubbing will take place. This causes the edge to weaken further and the cycle repeats until the tool fails. The second reason for the rapid increase in ¯ank wear can be attributed to the stripping of the coating on the tool. As cutting proceeds, the temperature at the tool±workpiece interface increases. The increase in temperature, in addition to the rubbing effect, causes the coating to wear off. When
this happens, the tool becomes uncoated at the tool±workpiece interface. The rubbing action at the interface will accelerate the ¯ank wear at a faster rate, thus causing tool failure. Fig. 3 shows the dynamic tangential force and the maximum ¯ank wear of the grooved tool for AISI 1148 (ASSAB 760) steel. The dynamic tangential force exhibits a similar trend when compared to that when machining AISI 4340 steel. To establish a tool-failure criterion for cutting with a grooved tool, it is proposed that the percentage increase of the dynamic tangential force be considered, as the dynamic tangential force exhibits an increasing trend when a grooved tool is at its advanced stage of tool wear. Statistical analysis using t-distribution for both AISI 4340 steel and AISI 1148 steel (10 samples each) has shown that it is possible to suggest a threshold setting for the onset of tool failure. The proposed threshold values for the AISI 4340 and AISI 1148 steel are 83% and 107%, respectively. On-line dynamic tangential force monitoring was subsequently conducted on AISI 4340 and AISI 1148 steel without stopping for ¯ank wear measurement. Figs. 4 and 5 show the results of the dynamic tangential force versus time. The
Fig. 3. Illustration of dynamic tangential force (thick line) and flank wear (thin line) for AISI 1148 steel.
290
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291
Fig. 4. Illustration of the dynamic tangential force versus time for AISI 4340 steel.
Fig. 5. Illustration of the dynamic tangential force versus time for AISI 1148 steel.
results con®rm the suggested threshold values for both AISI 4340 and AISI 1148 steel during turning. 5. Conclusions The experimental results show that there is a good correlation between the dynamic tangential force and ¯ank wear. The results also show that the dynamic tangential force ¯uctuates at a low value and increases steadily with tool wear on approaching tool failure. However, the absolute value varies under each cutting condition and bears little relationship to the magnitude of the tool wear. A personal computer for the measurement of the dynamic tangential force to monitor tool wear is feasible. The criterion on the threshold values of the percentage increase of the dynamic tangential force when cutting with a grooved tool can be used to indicate the onset of tool failure. 6. Nomenclature
back rake angle side rake angle end relief angle
r fn n kn E IX m l VBmax
side relief angle end cutting edge angle side cutting edge angle nose radius natural frequency of vibration of the tool holder mode of vibration parameter depending on the end condition Young's modulus of elasticity of the tool shank second moment of area of the tool shank crosssection mass per unit length of the tool shank effective length of tool overhang maximum flank wear
References [1] N.H. Cook, Tool wear and tool life, J. Eng. Ind. 95 (1973) 931. [2] P.K. Wright, A. Bagchi, Wear mechanisms that dominate tool life in machining, J. Appl. Metal Working 1(4) (1984) 15. [3] P.M. Lister, G. Barrow, Tool condition monitoring systems, Proceedings of the 26th International MTDR Conference, 1986, p. 271. [4] K.F. Martin, J.A. Brandon, R.I. Grosvenor, A. Owen, A comparison of in-process tool wear measurement methods in turning, Proceedings of the 26th International MTDR Conference, 1986, p. 289.
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291 [5] D. Li, J. Mathew, Tool wear and failure monitoring techniques for turning ± A review, Int. J. Mach. Tools Manuf. 30(4) (1990) 579. [6] K.S. Lee, L.C. Lee, S.C. Teo, On-line tool wear monitoring using a PC, J. Mats. Proc. Tech. 29 (1992) 3. [7] S.C. Teo, K.S. Lee, L.C. Lee, A study of the consistency of the tool wear characteristics and the criteria for the onset of tool failure, J. Mats. Proc. Tech. 37(1±4) (1993) 629. [8] S.B. Rao, Tool wear monitoring through the dynamics of stable turning, J. Eng. Ind. 108 (1986) 183.
291
[9] B. Lindstrom, B. Lindberg, Measurements of dynamic cutting forces in the cutting process ± A new sensor for in-process measurement, Proceedings of the 24th International MTDR Conference, 1983, p. 137. [10] L.C. Lee, K.S. Lee, C.S. Gan, On the correlation between dynamic cutting force and tool wear, Int. J. Mach. Tools Manuf. 29(3) (1989) 295. [11] G.J. Lay, Y. Saito, Y. Ito and Y. Maruhashi, Detection of tool wear by dynamic component of cutting force, J. Jpn. Soc. Prec. Eng. 50(7) (1984) 1117. [12] K.S. Lee, K.H.W. Seah, A.S. Lim, On-line tool failure detection, J. Inst. Engrs., Singapore 35(4) (1995) 53.
In-process tool-failure detection of a coated grooved tool in turning K.S. Lee*, K.H.W. Seah, Y.S. Wong, Lenny K.S. Lim Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore
Abstract With the increasing use of computer numerical control, there is a growing need to ensure a reliable system to optimise tool usage or tool wear. This paper presents a study on the fool failure of a coated grooved tool by monitoring the tool wear indirectly using the dynamic component of the tangential cutting force, Ft. Experiments conducted on AISI 4340 (ASSAB 705) and AISI 1148 (ASSAB 760) steels using a CNC lathe have revealed that there is a good correlation between the dynamic tangential cutting force and the ¯ank wear of the tool. The natural frequency of the recorded dynamic force corresponds to the natural frequency of the tool. The results indicated a trend for Ft, which starts at a low value and ¯uctuates about this level during the normal wear stage. As VBmax increases to about 0.4 mm, the force increases rapidly in a non-linear fashion until the tool fails. Statistical analysis using a t-distribution test has showed that the dynamic tangential force gave a promising threshold value for the prediction for AISI 4340 and AISI 1148 steel. On-line tool-wear monitoring software was used to track the dynamic force signals to predict the possible onset of tool failure. # 1999 Elsevier Science S.A. All rights reserved. Keywords: Tool-wear monitoring; Tool-failure detection
1. Introduction To realise the full potential of unmanned machining, the on-line identi®cation of the state of the cutting process and the detection of impending failure of the tool is mandatory. A tool is considered to have failed when it experiences excessive wear or premature tool fracture. Machining with a failed tool results in the deterioration of workpiece quality such as dimensional accuracy and surface roughness as well as the possibility of damaging the machine tool. A cutting tool may reach the end of its useful life due to excessive wear or premature tool breakage [1,2]. Machining with a blunt or broken tool can cause the workpiece quality to deteriorate and possible damage to the machine tool. Therefore, a reliable tool-wear monitoring technique is important in an unmanned machining situation to avoid such a catastrophe and allows optimum utilisation of the tool life, which is highly desirable. Several surveys and comparative studies on the methods of monitoring tool wear have been carried out [3±5]. Generally, the methods of monitoring tool wear can be categorised into direct and indirect approaches. The direct methods measure the ¯ank and crater wear of a cutting tool directly, using e.g., touch trigger probes, optical devices and *Corresponding author. E-mail: [email protected]
electrical resistance techniques. These methods are dif®cult to employ on-line because the sensors have to be in close proximity to the tool tip where wear or breakage takes place. The sensors are apt prone to being damaged in this situation. Furthermore, the detection of premature cutting edge failure is not possible whilst the tool is cutting. The indirect methods involve the measurement of cutting parameters, e.g. cutting temperature, cutting force, vibration and acoustic emission. These methods are more suitable for on-line monitoring as they allow uninterrupted machining to take place and eliminate problems that occur when using the direct methods. In a previous study [6,7], it was determined that the dynamic cutting force has a good correlation with the ¯ank wear of the tool. A number of studies have also found the measurement of the dynamic force to be effective in monitoring the tool wear [8±10]. Lay et al. [11] reported that the detection of ¯ank wear was possible by monitoring the dynamic force at a particular frequency. The ratio of the increment of the dynamic component to the static component is signi®cantly higher, roughly between 75% and 480%, for a ¯ank wear width of 0.2 mm. The measuring of the dynamic force produces a reasonable indication of tool wear and offers a reasonable speed of response. The present study investigates the use of a personal computer to perform the on-line tool-failure detection of
0924-0136/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved. PII: S 0 9 2 4 - 0 1 3 6 ( 9 9 ) 0 0 1 3 8 - 7
288
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291
area having a point load at the end. The resonant frequency can be calculated by means of the following equation: r kn 2 EIX fn Hz: 2 ml4
Fig. 1. Experimental set-up for tool-wear monitoring.
groove tool in turning. Software was used to track the dynamic force signals that correlate well with tool wear. 2. Experimental Fig. 1 shows the experimental set-up for the tool-wear monitoring. Experiments were conducted on an OKUMA CNC lathe. The workpiece materials used were AISI 4340 (ASSAB 705) and AISI 1148 (ASSAB 760) steel. The cutting inserts used were coated and grooved Sandvik SNMG120408 PM inserts, which were ®xed onto a Sandvik SBTR-16-4 R174.1-2525-12 tool holder, having a tool signature 58, 68, 58, 68, 158, 158 and r0.8 mm. The cutting forces were measured by a Kistler piezo-electric dynamometer TYPE 9123. A 25 MHz 486 personal computer equipped with a fast Fourier transform (FFT) card recorded the dynamic force signals. The FFT card is a model 25 digital signal processor board based on the Texas Instruments TMS320C25. The ¯ank wear of the tool was measured by means of a toolmaker's microscope. 3. Operating principle of the on-line sensor The dynamic forces generated in metal cutting can be attributed to many causes, the most predominant amongst which are the oscillation of the cutting tool, the shearing action of the chip, the uneven surface and the non-homogeneity of the workpiece. The force signals can be measured by the dynamometer holding the tool. Lay et al. [11] have investigated the dynamic cutting force and found that more meaningful results can be derived when the dynamic force is presented in the frequency spectrum. A prominent peak was observed in the frequency spectrum that remained substantially constant throughout the life of the cutting tool. The origin of the peak frequency was found to be related to the resonant frequency of the tool holder [10]. The resonant frequency of the tool holder can be represented by a simple cantilever beam with a uniform cross-sectional
There are four modes of vibration for a simple cantilever beam. Rao [8] has veri®ed that the ®rst mode usually dominates as the tool wears. It can be deduced that when machining with a new cutting tool, the dynamic force is small because of minimum rubbing contact between the tool and the workpiece. As the ¯ank wear-land develops during machining, the rubbing contact between the tool and the workpiece increases, resulting in the increase in the dynamic force amplitude. On approaching the end of the tool life, there is severe thermal weakening at the edge of the cutting tool, and the tool begins to wear off at a faster rate. The blunt tool causes an additional heat source as it rubs against the workpiece. This further weakens the tool and plastic collapse occurs subsequently. This is one wear mechanism that affects the tool life, as identi®ed by Wright [2]. Since the dynamic force was observed to have a good correlation with the tool wear, it is possible to use a personal computer to monitor the dymamic force during machining. A software program developed by Lee et al. [12] was used to monitor the dynamic force of the grooved tool. A personal computer equipped with a fast Fourier transform card was used to perform the necessary data acquisition and FFT processing. The FFT PROCESS subroutine processes the digital signals into a frequency spectrum. The signals are the averages of every 128 frames of measurement to smoothen out any ¯uctuations. The software developed so far allows for continuous monitoring of tool wear or intermittent stoppages and monitoring. Statistical analysis of the experimental results revealed that it is possible to set a threshold value for the percentage increase in dynamic tangential force, Ft, to predict tool failure with 99% con®dence level. 4. Results and discussion A comprehensive study has shown that both the feed and tangential component of the dynamic force correlates well with the tool ¯ank wear. Experimental results reported earlier [6,7] show that the absolute value of the dynamic force bears little relationship to the magnitude of the tool wear. However, a good relationship is found to exist between the trend of the dynamic force and the ¯ank wear. Fig. 2 shows the dynamic tangential force and the maximum ¯ank wear of the grooved tool for AISI 4340 (ASSAB 705) steel. Generally, the dynamic tangential force Ft ¯uctuates about a mean value as the cutting proceeds, this continuing until the ¯ank wear reaches approximately 0.4 mm, which is followed immediately by rapid increase in the value of Ft. The trend of the dynamic tangential force
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291
289
Fig. 2. Illustration of the dynamic tangential force (thick line) and flank wear (thin line) for AISI 4340 steel.
observed is in contrast to that of an ungrooved tool, which exhibits a monotonic increase followed by a fall towards the end of the tool life [12]. It was also noted that during cutting, the dynamic tangential force was low (in the region of 10± 35 N). This can be attributed to the grooved nature of the tool (SNMG120408 PM), which offers a higher normal rake angle as compared to that of an ungrooved tool. The trend of the dynamic tangential force observed can be explained by considering two factors: the increase in contact surface area between the tool and the workpiece, and the temperature at the tool±workpiece interface. During the initial stage of cutting, the ¯ank face experiences normal wear as a result of rubbing between the tool and the workpiece, which grows slowly. On approaching tool failure, the wear land would have increased many times over. This causes weakening of the cutting edge. Since a weakened edge will deform and recede, more rubbing will take place. This causes the edge to weaken further and the cycle repeats until the tool fails. The second reason for the rapid increase in ¯ank wear can be attributed to the stripping of the coating on the tool. As cutting proceeds, the temperature at the tool±workpiece interface increases. The increase in temperature, in addition to the rubbing effect, causes the coating to wear off. When
this happens, the tool becomes uncoated at the tool±workpiece interface. The rubbing action at the interface will accelerate the ¯ank wear at a faster rate, thus causing tool failure. Fig. 3 shows the dynamic tangential force and the maximum ¯ank wear of the grooved tool for AISI 1148 (ASSAB 760) steel. The dynamic tangential force exhibits a similar trend when compared to that when machining AISI 4340 steel. To establish a tool-failure criterion for cutting with a grooved tool, it is proposed that the percentage increase of the dynamic tangential force be considered, as the dynamic tangential force exhibits an increasing trend when a grooved tool is at its advanced stage of tool wear. Statistical analysis using t-distribution for both AISI 4340 steel and AISI 1148 steel (10 samples each) has shown that it is possible to suggest a threshold setting for the onset of tool failure. The proposed threshold values for the AISI 4340 and AISI 1148 steel are 83% and 107%, respectively. On-line dynamic tangential force monitoring was subsequently conducted on AISI 4340 and AISI 1148 steel without stopping for ¯ank wear measurement. Figs. 4 and 5 show the results of the dynamic tangential force versus time. The
Fig. 3. Illustration of dynamic tangential force (thick line) and flank wear (thin line) for AISI 1148 steel.
290
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291
Fig. 4. Illustration of the dynamic tangential force versus time for AISI 4340 steel.
Fig. 5. Illustration of the dynamic tangential force versus time for AISI 1148 steel.
results con®rm the suggested threshold values for both AISI 4340 and AISI 1148 steel during turning. 5. Conclusions The experimental results show that there is a good correlation between the dynamic tangential force and ¯ank wear. The results also show that the dynamic tangential force ¯uctuates at a low value and increases steadily with tool wear on approaching tool failure. However, the absolute value varies under each cutting condition and bears little relationship to the magnitude of the tool wear. A personal computer for the measurement of the dynamic tangential force to monitor tool wear is feasible. The criterion on the threshold values of the percentage increase of the dynamic tangential force when cutting with a grooved tool can be used to indicate the onset of tool failure. 6. Nomenclature
back rake angle side rake angle end relief angle
r fn n kn E IX m l VBmax
side relief angle end cutting edge angle side cutting edge angle nose radius natural frequency of vibration of the tool holder mode of vibration parameter depending on the end condition Young's modulus of elasticity of the tool shank second moment of area of the tool shank crosssection mass per unit length of the tool shank effective length of tool overhang maximum flank wear
References [1] N.H. Cook, Tool wear and tool life, J. Eng. Ind. 95 (1973) 931. [2] P.K. Wright, A. Bagchi, Wear mechanisms that dominate tool life in machining, J. Appl. Metal Working 1(4) (1984) 15. [3] P.M. Lister, G. Barrow, Tool condition monitoring systems, Proceedings of the 26th International MTDR Conference, 1986, p. 271. [4] K.F. Martin, J.A. Brandon, R.I. Grosvenor, A. Owen, A comparison of in-process tool wear measurement methods in turning, Proceedings of the 26th International MTDR Conference, 1986, p. 289.
K.S. Lee et al. / Journal of Materials Processing Technology 89±90 (1999) 287±291 [5] D. Li, J. Mathew, Tool wear and failure monitoring techniques for turning ± A review, Int. J. Mach. Tools Manuf. 30(4) (1990) 579. [6] K.S. Lee, L.C. Lee, S.C. Teo, On-line tool wear monitoring using a PC, J. Mats. Proc. Tech. 29 (1992) 3. [7] S.C. Teo, K.S. Lee, L.C. Lee, A study of the consistency of the tool wear characteristics and the criteria for the onset of tool failure, J. Mats. Proc. Tech. 37(1±4) (1993) 629. [8] S.B. Rao, Tool wear monitoring through the dynamics of stable turning, J. Eng. Ind. 108 (1986) 183.
291
[9] B. Lindstrom, B. Lindberg, Measurements of dynamic cutting forces in the cutting process ± A new sensor for in-process measurement, Proceedings of the 24th International MTDR Conference, 1983, p. 137. [10] L.C. Lee, K.S. Lee, C.S. Gan, On the correlation between dynamic cutting force and tool wear, Int. J. Mach. Tools Manuf. 29(3) (1989) 295. [11] G.J. Lay, Y. Saito, Y. Ito and Y. Maruhashi, Detection of tool wear by dynamic component of cutting force, J. Jpn. Soc. Prec. Eng. 50(7) (1984) 1117. [12] K.S. Lee, K.H.W. Seah, A.S. Lim, On-line tool failure detection, J. Inst. Engrs., Singapore 35(4) (1995) 53.