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CIM: On a New Theoretical Approach of Integration
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CIM: ON A NEW THEORETICAL APPROACH OF INTEGRATION T. T6th and I. Detzky U~porlll/fIIl
oj Prodl/rliulI LlIgill"l'I"illg. Tt'(/tlli(o/ .\I t.lko/t.. II I/llgol\'
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Abstract. It is expedient to study up-to-date theoretica l means and prac tical resour ces of the automation of mechanical engineering through the structure, functions, environment interrelations and the most important features of Computer Integrated Manufacturing (C IM) systems because the highest level of dual unity of automation for material- and data processing can be realized by them. Classification of CIM systems and their subsystems is generally based on the automation levels and functional ro l es, i.e. on the external features of the systems and subsystems. In this paper the authors wi l l prove that there is another classification method well-established from the theoretical point of view, which de termines the internal hierarchy of part manufacturing systems on the basis of objective features. Starting from a uniformable model of t hese systems the process optimization principles of discrete manufacturing wi l l also be generalized. Keywords. Computer Integrated Manufacturing; automation; hierarchical systems; computer aided process planning; CAD; CAM; optimization.
I NTRODUCTION. THE CONCEPT OF CIM According t o a well - known interpretation CIM (Computer Integrated Manufacturing) is a high - technology approach to more efficient manufacturing. From the point of view of practical realization CIM can be considered as a complex manufacturing system based on intelligent electronics Ilhich is a proper integration of manufacturing equipment, a hierarchical information control system and sophisticated operating softllares. The following definitions ( Williams,198S ) mainlye,nphasize the information processing aspec t of CH1: • CIM is integration of systems for measurement and control of all pro duction process operations lIith systems for managerial control of the factory and a l'l ide range of corporate business function; • CIM is a methodology for automating the gathering and sharing of informa tion among computer systems to estab lish a closed l oop in time feedback system for effective planning and control; • CIM is the systematiC implementation of computer technolog y within the company to achieve long ter ~ goals of maximizing efficiency, productivity and profitability. In Fig.l. a general structure and informa tion mo del of CIM systems are demonstrated. Th 2 are a 1/ i t h the 12 g end " I i IT EGRA TE D SYSTEMS ARCHlTECTUP.E" being in the centre of the Figure relate s 'to a hardllare- sofhlare cO
including computer networks organ i zed in a hierarchical ~I ay. It means the concent r at ed HW+SW resources of an informa ti on syst em functioning as a main compo ne nt o f CI M a nd a common data base belongs t o it. The degree of organization of integrated info r mat i on flow is the highest one between the inte grated subsystems and the common data base. Th e thick, hatched arrows relate to this. The factory automation segment means the most important tasks of integrated mate r ia l processing . Integrated data process i ng is demonstrated by means of th r ee further segments, they are: design engineering, manufacturing engineering, as Ile11 as manu facturing planning and control . The thick black arrOllS refer to the information exchange bet\leen the neighbour ing segmen t s . CIM, in its final extension, supposes such a data structure that makes an optional data f l oll possible towards an y part of the system. As it can be seen in Fig .1. the four internal segments are surrounded by a neare r and a farther information medium. Advancing ouhla rds in Fig .1. the degree of integr ation is decreasing. THE USUAL MAIN DIRECTIONS OF HHEGRATIOtJ The complexity of concept of CIM appea rs in the fact that it includes integration of three directions. They are as follolls: a ) Fitting and jo ining the manufacturing phases follOlling successively in order t o maxim ize the product output ( sec tion in time, optimal manufacturing program ) ;
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T. TOlh and I. Delzh
On the lowest level people were ousted by automation in the industrially developed countries a long ago. Programmable automation has been expanding since appearance of microprocessors (intelligent controllers). On the second level one or two manufacturing equipment and a quali ty controlling station create a uni t together. Typical controlling means are programmable part uni ts controlled by }JP-s. For human controlling and interrupting keyboa r d and d i s p 1 a y de vices are used. The scale of electronic processing times and response times extends from some seconds to some minutes.
Fig.l. General structure and information model of CIM systems. b) Integration of controlling levels superposed ("Organization pyramid"); c) Lateral integration of company functions. In the "section" a) it can be examined hovl the manufacturing phases follo~ing successively joint each other and how they can be combined and concentrated. Here the most important functions of CIM are to minimize the stock being in the system and to maximize the intensity of product output. To perform these, external material transport coming in time and sharply scheduled internal manufacturing are required . The ele ments of the system (including the remain personnel ) are subordinated to the requirement of continuous \lork (just-in-time=JIT ) . In the "section" b) a lie 11-0 rga n i zed, deep 1 ystructurized computer control hierarchy is needed to the undisturbed manufacturing and continuous motions of materials, as well as semi-finished prod ucts . Fr om the theoretical analyses of competent publications ( e.g. Buzacott (1982 ) , OTA Rep o rt (1 984 ) , Kusiak (1985 ) , Yeomans , Choudr y a nd ten Hagen (1985 ) , Primrose and Leonard ( 1986 ) , Scheer ( 19B7 ) , Schuy (1987) the inference can be dra\ Jn that a CIM s yste m can be dissected i n to 5 hierarchical le vels. Ad vancing botto m-up they are as follows: ( 1) The level of direct control o f manufacturing process ( Process le vel ) ; (2) Work Station Level; (3) The level of autonomous manufact uring units ( Cell Le vel ) ; ( 4) The level of manufacturing contr o l subsystems ( Center Level ) ; (5) The level of company management (Top Le vel).
As regards the third level it is to be underlined that European and American experts interprete the extension of this level in different way but there is a mutual understanding in that the proper basic units of CIM belong to this level. According to the narrDller Europe a n interpretation a CIM unit of such level contains generally more than two automatic - mainly NC/CNC - machine tools, special equipment, robots and aut 0 mat i c mate r i a 1 ha n d 1 i ng means. The larger American interpretation extend this level to workshops, emphasizing that any of these units is subord i na t e d to the p roce s sing r y t hm of the following unit. For computer controlling a powerful professional microcomputer (e.g. IBM PC AT) or a larger microcomputer (e.g. mic r 0 VAX) is re qui r ed, the scale of respon s e times extends from some minutes to cca one hour. The fourth controlling level co-ordinates all the manufacturing subsystems. If there is such a controlling level in the given CIM system, the access to the lower levels can only be carr ied out through this center level under normal operating circumstances. The typical controlling equipment is a powerful minicomputer ( e. g. DEC VAX 11/7xx ) or a main frame computer vii th a simpler configuration. Response time - in case of more sophisticated decision sequences - can extend more hours. The fifth le vel is, properly, the level of production planning and control on the to~ of s u c h an" 0 r g ani z a t ion p y r a mid" in Ilhich the rea r e the pr e v i 0 u sly des cri bed CO"lPU ter hierarchy and manufacturing automation. The typical equipment suitable for controlling is a powerful large-size ( main frame ) computer with an appropriate configuration ( e . g. I BM 43 x x ) . The de c i s ion and respons e times can extend the inter vals longer than one day. The "section" c ) examines co-ordination of the acti vities connecting to manufacturing: it takes, reall y , possibilities of the lateral integration of company functions into account. They are, among other things:CAE, CAD, CAPP, CAM, CAST, CAQ and MRP. ( The interpretations of the5e abbreviations are assumed to be known ) .
:\ew Theoretical Approach of Integration
22 1
attempt to demonstrate the three "sections" of CIM, in strongly simplified way,in Fig.2.
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and structural decomposition of machining/ processing systems we have to start from those objective and more deep - sea ted physical conditions \·I hich determine the material processes TOP LEVEL of subsystems, i.e. the coming into ex (ENTER LEVEL istence of nell,useful properties. \Ii thout 'Workshop System • these neither level (ELL LEVEL • Manufacturing Syshm of integration nor objective contents WORK STATION LEVEL • Machin ing / Processing of flexibili t y can S stem be explained. • Mechanical System • 'Workpiece-Tool System
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SYS TEM- TH EORETICAL APPROACH Structure and process Her e if Yle speak about a ClM system Yle think of physica ll y existing objects on all occa sions. In this sense we also talk about reality of economical environment including manufacturing technology systems which is interlloven into an organization by three essential stream networks. They are as fo llows: material streams, information streams and value streams .
Consequently, the CI M s Ystem hierarchy Technology ltl/ets based on the autoRealised mation levels and functional roles, i.e. on the external features of the systems and s ubsystems, has to be complemented lIith at least hID further steps upllards from below in order to obtain an objective conception about adequate connections of functions and processes (c.f. with the right ha n d si d e par t 0 f Fig. 2 ., proposed by Oetzky (1988) and T6th (1988)). This classification determines the internal hierarchy of part manufacturing systems .
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The functional substance of the manufacturing technology systems is that material trans formation process which can automatically be executed along material streams. The common substance of each such trans formation is the objectivation on technological information related to the usef~l material properties and planned states ( F ig. 3). Here it has to be emphasized that rough material flol'ling in the system, independently of how it obtained its given state, in how many sorts of, and in IIhat kinds of technological phases, resists a newer transformation as a "natural material " in all cases. Therefore a state of change al ways t akes place according to objective laws of nature . Under such circu mstances technology is able to influence the condi tions system (constraints ) only. Thus, in another approach, technology can be defined as the science of conditions systems of the law s of nature. In the last analysiS all that Ylhat builds over the material processes in hierarchy is a function of possibilities and limits determined by objecti ve laYls and technical conditions, in a structural way too. By means of this train of thought we \Ianted t o ver if y that in the course of hierarchical
Fig.3. The substance of materia l transformation process Analyzing the technological processes The authors demonstrate the analysis of discrete manufacturing technology processes through an example taken from the area of machining. This area represents high technology considering its specific applied means and it reflects the clearist systemmodels . From the economical point of view processes of an autonomous technological system can be classified as follows:
222
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• primary pr ocesses are th ose in which the object of work i s present from beginning to end and som e specific pr operty or state of it changes in the expected IJay (cutting , heat treat me nt etc.); • secondary proce sses are those in which the object of wor k is prese n t but without changing any specific property or state o f it and its relative position only is modified (part handling, storage measuring etc.); • auxiliary proces ses are those in which the object of work is not present but the moments can be allocated identifiably to some object of work and they are necess3r y for generating the primary processes ( preparing the means and information,machineadjustment etc. ) ; • maintenance proce sses are those \Jhich cannot be allocated identifiably to a given object of IJork but they are directl y needed for the predestined internal functioning of the technologica l sys tem ( energy supply, machine maintenance, e tc.); • environment processes are those \Jhich take place within the system but they are not reasonable for the object of work or the internal functioning of the system. Their necessit y is reasonable for such aims which are determined by the superordinate environment (mo nitoring /co ntrolli ng requirements, interventional constraints, etc.). This division make s it po ss ible to give an account of the cos t s of technological processes and to analyse them economically. Primary and secondary processes are together named basic processes. These have an impor tant role in proce ss planning and manufacturing programming. In our example the quality of a certain machine construction is determined b y the proper spatial relati ons and dimensions of the surfaces of parts in the ove rwhelming majority of cases. Thus, from the aspect of quality, a geo me trical hierarchy of parts can be enforced in dissecting the processes in the first place. Accordingly, the following steps can be separated ( see:Fig.4 ) : • operation group i s that phase of the whole working process in which a certain part, starting from the rough piece, obtains its finished configur ation suitable for assembling and to which some mach inegroup (manufactu ring sys t em ) can be allocated in general; • operatio n is that in which on e of the cha racteristic configurations of the part having a common symmetry ( shape d - group ) is machined and to this, on the basis of symmetry, some kind o f universal machine tool type ( a homogeneous mach ine tool group) can be allocated; • suboperation ( partial ope ration ) is that in \Jhich one of the shapes (su rface groups ) of a given configuration is ma chined and a typical set-up method a nd a clamping device set of common basis are attached to this; • operation element is that in which only on e surfaCe of a ce rt ain shape is machined according t o given dimension pa ra mete rs and tolerances and to this some kind of tool t ype and tool path can be allocated.
• momentum is such a ch ange of state which, in the geometrical sence, yields forming surface elements o f a pre sc ribed quality and cutting parameters are attached to thi s . The enumerated hierarchical decomposition included only details of the different phases of the primary pro c ess but the realizing means allot able to them were also marked. The latters refer to the possible variety of secondary and auxiliary processes connecting with the different levels. The se co - ordinations co ns titute the base of process planning. Theoretical models A signi ficant part of practical and organizational requirements i s formulated in the form of exact criteria f o r organizing the automated technologcal systems in a hierarchical way. The general requirements of the models valid for any level are as fol l o ws: • Boundary surfaces of s ubsy s tems have to be defined in suc h a manner that the connecti ons and streams thr ough them should be expressed by means of mathematical ( l ogic al and arithmetical) variables. • Structures of subsyste ms have to be synthetized in such a wa y that their common functi on ing can be described, on the base of independent diSCiplines if posSible, by laws and constraints treatable mathematically. • For the subsystems such optimum criteria should be interpreted which obtain a complete conditions sys tem by means of optimization of the sys tem above them. Fulfilment and concretization of the requirements enumerated above depend on the adequate disciplin e applicable in the first place. In the part manufacturing exemplifying discontinuous processes these are as follo\Js: -- operations re sea rch for ma nufacturing -- theor y of ope rati ons sequ ences -- mechatro nics for machine tools -- cutting theor y. Through the stepping we relate to a pos sible hierarchy of the system-models. We have to deal with the general requirement o f optimization in mo re detail. Technological opti miz ati on Universali t y o f the problem r esults from the fact that no specia l science can avoid optimum pr ob le ms if it derives its product s from aims of soci al origin. Th ese have also long appeared in several methodological disciplines independently ( "Mathe matical Pro g r a mmi n g", " 0 per a t ion s Re s ear ch", " Oeci sions Theory" ). Technical pr oblems can be divided into two large groups: • Technological pr ob lem s : all the possible processes of a given sys t em existing phySically have a subset whi ch includs realizing possibilities of a product described in some kind of modul structure. From them we must select t hat process varian t \Jhich is most sui table for prescribed ai m exterior to the system. • Oesign problems: all th e possible models o f a system of specific kno\Jledge existing in th oug ht have a subset which includes realizing possibilities of a function
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Thus, \·Ie need: • va ri ables (x), logical or a r ithme t i cal values of which a r e sel e ct a ble a nd r ealiz ab l e independen t ly of one a nothe r ; • functio ns or r elat i ons (M(x)) whi ch a r e interpreted by means of the vari a bles and given by the t ools i ndependen tl y o f the pr oblem; • functions or relations (A(x)) wh ic h a r e interp r e t ed by means o f the va r iab les and give n by the pr oblem ind e pe nde n tl y of the too l s;
224
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• a function U(x)) \,hich can be interpreted by means of t he va riables and it is de termined by the external aim independ ently of both the tools and the problem . Solution of the optimization prob l em, gen eraliz i ng the symbols, can be formulated as fo ll o\/s: 1. XT ' totality of the technical field of knowledge has to be assumed, a vector of whi ch, x t XT , \
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Fr om the scheme it is easy to see that not the optimum - searching procedure itself, de noted by the last (5th) step, i s primarily significant from the point of view of so lution, but com posin g those sets, ~hich have to be created in the previous steps. In the Fig. 5. the v isual models of one-level and of multi - level optimIzation are demonstrated. (In the interest of simplici t y feedback is not denoted. ) . An example from cutting techn olo gy The most up-to-date systems which represent high technology in production enginee ring are connected with cutting as a basic proce ss. In Fig.6, as an example, we have summarized th ose characteristics by means of ~hich the classes of technological systems can be identified. Alon!J the secondary and auxiliary processes essentially similar kinds of level s can be se parated on the basis of the models suitable for specific functions. Especially we empha sized i mportance of the addi tive objective function which comp reh ends the . obje ct iv e funcllon hiearchy of systems. For the sake of a uniform technological aspect we also propose to take into account the objective costs by additional equivalent times computing with the hourly cos t s of the direct environm ent. va li dity set of so lu hon variants
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Fig . 5. Visual models of optimization a / One-le vel model b / Multi -le vel model
REFERENCES William s, P.J.(1985) . Com puter Integrated Manu=facturing (C IM ). A Man agament Perspective. Ryerson Poly technical In stitute, Toronto. ( Draft papers). Buzacott,J.A. (19 82). Th e Fundamental Pr in ciples of Felexibility in ~anu facturing Systems . Proceedings of t he 1st International Conference on FMS, Brighton, United Kingdom. Office of Technology Assess ment ( OTA ) Report ( 1984 ) . Compu ter i zed Manufacturing Automation . ( Employment, Education and t he Wor k~. Congress of The Uni ted States, Washington. Kusiak, A. ( 1985 ) Flexible Manufacturing Systems: a Structural Approach. Internati onal Journal of Production ResearCh, Vol. 23, pp. 1057 - 1073. Yeomans, R.W., Choud r y,A.., and ten Hagen, P.J.~ . ( 1985 ) . Design Rules fo r a CH1 System . Ilo rth-Hol land, Amsterdam. ( cont.)
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tems, s umm arizi ng th e Fig . 6. Intern al hierarc hy of part ~ a n ulacturing s ys the cutting pr oc es s es of case the in cs teristi charac ant import most Primro se , P.L., and Le onard, R. ( 1986 ) . Identi fying the Flexib ility of FMS System s . Procee dings of the 26th I n ter in nation al Machin e Tool DeSign and Research Confer ence held in Manch ester. Dept.o f Mech. Engng. , Uni versit y of Hanche s ter Institu te o f Scien c e and Techno log y in Assoc. with MacMi llan Publis her s Ltd, pp.167 -173. Scheer ,A.-U . ( 1987 ) . CIH:De r comput erge steuer te Indust riebet rieb. Spri nger Verlag , 8erlin - Heidelb erg-Ne w Yo rkLondon -Paris- Tokyo. Schuy,K .J. ( 1987 ) . IBM Strateg y and Direction 3. Mainz (Draft paper) . Detzky ,I. ( 1988 ) . Manufa cturing Te c hnology 11. Theore tical Part 1. Educat ional Publis her,Bu dapest (in Hungar ian ) .
Toth,T . ( 1988 ) . Com puter Aided Proc ess Plannin g in Manufa cturi ng Te chn o l ogy . Doctor al Disser tati on f or Hunc ar i a n Academy o f SCienc e s , Budape s t ( in Hungar ian ) .
(:o P\ r ig lH
CIM: ON A NEW THEORETICAL APPROACH OF INTEGRATION T. T6th and I. Detzky U~porlll/fIIl
oj Prodl/rliulI LlIgill"l'I"illg. Tt'(/tlli(o/ .\I t.lko/t.. II I/llgol\'
['111<',.,..1 /'.\'
jur
I-/~m'\'
11/(/11.111\' .
Abstract. It is expedient to study up-to-date theoretica l means and prac tical resour ces of the automation of mechanical engineering through the structure, functions, environment interrelations and the most important features of Computer Integrated Manufacturing (C IM) systems because the highest level of dual unity of automation for material- and data processing can be realized by them. Classification of CIM systems and their subsystems is generally based on the automation levels and functional ro l es, i.e. on the external features of the systems and subsystems. In this paper the authors wi l l prove that there is another classification method well-established from the theoretical point of view, which de termines the internal hierarchy of part manufacturing systems on the basis of objective features. Starting from a uniformable model of t hese systems the process optimization principles of discrete manufacturing wi l l also be generalized. Keywords. Computer Integrated Manufacturing; automation; hierarchical systems; computer aided process planning; CAD; CAM; optimization.
I NTRODUCTION. THE CONCEPT OF CIM According t o a well - known interpretation CIM (Computer Integrated Manufacturing) is a high - technology approach to more efficient manufacturing. From the point of view of practical realization CIM can be considered as a complex manufacturing system based on intelligent electronics Ilhich is a proper integration of manufacturing equipment, a hierarchical information control system and sophisticated operating softllares. The following definitions ( Williams,198S ) mainlye,nphasize the information processing aspec t of CH1: • CIM is integration of systems for measurement and control of all pro duction process operations lIith systems for managerial control of the factory and a l'l ide range of corporate business function; • CIM is a methodology for automating the gathering and sharing of informa tion among computer systems to estab lish a closed l oop in time feedback system for effective planning and control; • CIM is the systematiC implementation of computer technolog y within the company to achieve long ter ~ goals of maximizing efficiency, productivity and profitability. In Fig.l. a general structure and informa tion mo del of CIM systems are demonstrated. Th 2 are a 1/ i t h the 12 g end " I i IT EGRA TE D SYSTEMS ARCHlTECTUP.E" being in the centre of the Figure relate s 'to a hardllare- sofhlare cO
including computer networks organ i zed in a hierarchical ~I ay. It means the concent r at ed HW+SW resources of an informa ti on syst em functioning as a main compo ne nt o f CI M a nd a common data base belongs t o it. The degree of organization of integrated info r mat i on flow is the highest one between the inte grated subsystems and the common data base. Th e thick, hatched arrows relate to this. The factory automation segment means the most important tasks of integrated mate r ia l processing . Integrated data process i ng is demonstrated by means of th r ee further segments, they are: design engineering, manufacturing engineering, as Ile11 as manu facturing planning and control . The thick black arrOllS refer to the information exchange bet\leen the neighbour ing segmen t s . CIM, in its final extension, supposes such a data structure that makes an optional data f l oll possible towards an y part of the system. As it can be seen in Fig .1. the four internal segments are surrounded by a neare r and a farther information medium. Advancing ouhla rds in Fig .1. the degree of integr ation is decreasing. THE USUAL MAIN DIRECTIONS OF HHEGRATIOtJ The complexity of concept of CIM appea rs in the fact that it includes integration of three directions. They are as follolls: a ) Fitting and jo ining the manufacturing phases follOlling successively in order t o maxim ize the product output ( sec tion in time, optimal manufacturing program ) ;
220
T. TOlh and I. Delzh
On the lowest level people were ousted by automation in the industrially developed countries a long ago. Programmable automation has been expanding since appearance of microprocessors (intelligent controllers). On the second level one or two manufacturing equipment and a quali ty controlling station create a uni t together. Typical controlling means are programmable part uni ts controlled by }JP-s. For human controlling and interrupting keyboa r d and d i s p 1 a y de vices are used. The scale of electronic processing times and response times extends from some seconds to some minutes.
Fig.l. General structure and information model of CIM systems. b) Integration of controlling levels superposed ("Organization pyramid"); c) Lateral integration of company functions. In the "section" a) it can be examined hovl the manufacturing phases follo~ing successively joint each other and how they can be combined and concentrated. Here the most important functions of CIM are to minimize the stock being in the system and to maximize the intensity of product output. To perform these, external material transport coming in time and sharply scheduled internal manufacturing are required . The ele ments of the system (including the remain personnel ) are subordinated to the requirement of continuous \lork (just-in-time=JIT ) . In the "section" b) a lie 11-0 rga n i zed, deep 1 ystructurized computer control hierarchy is needed to the undisturbed manufacturing and continuous motions of materials, as well as semi-finished prod ucts . Fr om the theoretical analyses of competent publications ( e.g. Buzacott (1982 ) , OTA Rep o rt (1 984 ) , Kusiak (1985 ) , Yeomans , Choudr y a nd ten Hagen (1985 ) , Primrose and Leonard ( 1986 ) , Scheer ( 19B7 ) , Schuy (1987) the inference can be dra\ Jn that a CIM s yste m can be dissected i n to 5 hierarchical le vels. Ad vancing botto m-up they are as follows: ( 1) The level of direct control o f manufacturing process ( Process le vel ) ; (2) Work Station Level; (3) The level of autonomous manufact uring units ( Cell Le vel ) ; ( 4) The level of manufacturing contr o l subsystems ( Center Level ) ; (5) The level of company management (Top Le vel).
As regards the third level it is to be underlined that European and American experts interprete the extension of this level in different way but there is a mutual understanding in that the proper basic units of CIM belong to this level. According to the narrDller Europe a n interpretation a CIM unit of such level contains generally more than two automatic - mainly NC/CNC - machine tools, special equipment, robots and aut 0 mat i c mate r i a 1 ha n d 1 i ng means. The larger American interpretation extend this level to workshops, emphasizing that any of these units is subord i na t e d to the p roce s sing r y t hm of the following unit. For computer controlling a powerful professional microcomputer (e.g. IBM PC AT) or a larger microcomputer (e.g. mic r 0 VAX) is re qui r ed, the scale of respon s e times extends from some minutes to cca one hour. The fourth controlling level co-ordinates all the manufacturing subsystems. If there is such a controlling level in the given CIM system, the access to the lower levels can only be carr ied out through this center level under normal operating circumstances. The typical controlling equipment is a powerful minicomputer ( e. g. DEC VAX 11/7xx ) or a main frame computer vii th a simpler configuration. Response time - in case of more sophisticated decision sequences - can extend more hours. The fifth le vel is, properly, the level of production planning and control on the to~ of s u c h an" 0 r g ani z a t ion p y r a mid" in Ilhich the rea r e the pr e v i 0 u sly des cri bed CO"lPU ter hierarchy and manufacturing automation. The typical equipment suitable for controlling is a powerful large-size ( main frame ) computer with an appropriate configuration ( e . g. I BM 43 x x ) . The de c i s ion and respons e times can extend the inter vals longer than one day. The "section" c ) examines co-ordination of the acti vities connecting to manufacturing: it takes, reall y , possibilities of the lateral integration of company functions into account. They are, among other things:CAE, CAD, CAPP, CAM, CAST, CAQ and MRP. ( The interpretations of the5e abbreviations are assumed to be known ) .
:\ew Theoretical Approach of Integration
22 1
attempt to demonstrate the three "sections" of CIM, in strongly simplified way,in Fig.2.
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and structural decomposition of machining/ processing systems we have to start from those objective and more deep - sea ted physical conditions \·I hich determine the material processes TOP LEVEL of subsystems, i.e. the coming into ex (ENTER LEVEL istence of nell,useful properties. \Ii thout 'Workshop System • these neither level (ELL LEVEL • Manufacturing Syshm of integration nor objective contents WORK STATION LEVEL • Machin ing / Processing of flexibili t y can S stem be explained. • Mechanical System • 'Workpiece-Tool System
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SYS TEM- TH EORETICAL APPROACH Structure and process Her e if Yle speak about a ClM system Yle think of physica ll y existing objects on all occa sions. In this sense we also talk about reality of economical environment including manufacturing technology systems which is interlloven into an organization by three essential stream networks. They are as fo llows: material streams, information streams and value streams .
Consequently, the CI M s Ystem hierarchy Technology ltl/ets based on the autoRealised mation levels and functional roles, i.e. on the external features of the systems and s ubsystems, has to be complemented lIith at least hID further steps upllards from below in order to obtain an objective conception about adequate connections of functions and processes (c.f. with the right ha n d si d e par t 0 f Fig. 2 ., proposed by Oetzky (1988) and T6th (1988)). This classification determines the internal hierarchy of part manufacturing systems .
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The functional substance of the manufacturing technology systems is that material trans formation process which can automatically be executed along material streams. The common substance of each such trans formation is the objectivation on technological information related to the usef~l material properties and planned states ( F ig. 3). Here it has to be emphasized that rough material flol'ling in the system, independently of how it obtained its given state, in how many sorts of, and in IIhat kinds of technological phases, resists a newer transformation as a "natural material " in all cases. Therefore a state of change al ways t akes place according to objective laws of nature . Under such circu mstances technology is able to influence the condi tions system (constraints ) only. Thus, in another approach, technology can be defined as the science of conditions systems of the law s of nature. In the last analysiS all that Ylhat builds over the material processes in hierarchy is a function of possibilities and limits determined by objecti ve laYls and technical conditions, in a structural way too. By means of this train of thought we \Ianted t o ver if y that in the course of hierarchical
Fig.3. The substance of materia l transformation process Analyzing the technological processes The authors demonstrate the analysis of discrete manufacturing technology processes through an example taken from the area of machining. This area represents high technology considering its specific applied means and it reflects the clearist systemmodels . From the economical point of view processes of an autonomous technological system can be classified as follows:
222
T. T6th and I. Detzb"
• primary pr ocesses are th ose in which the object of work i s present from beginning to end and som e specific pr operty or state of it changes in the expected IJay (cutting , heat treat me nt etc.); • secondary proce sses are those in which the object of wor k is prese n t but without changing any specific property or state o f it and its relative position only is modified (part handling, storage measuring etc.); • auxiliary proces ses are those in which the object of work is not present but the moments can be allocated identifiably to some object of work and they are necess3r y for generating the primary processes ( preparing the means and information,machineadjustment etc. ) ; • maintenance proce sses are those \Jhich cannot be allocated identifiably to a given object of IJork but they are directl y needed for the predestined internal functioning of the technologica l sys tem ( energy supply, machine maintenance, e tc.); • environment processes are those \Jhich take place within the system but they are not reasonable for the object of work or the internal functioning of the system. Their necessit y is reasonable for such aims which are determined by the superordinate environment (mo nitoring /co ntrolli ng requirements, interventional constraints, etc.). This division make s it po ss ible to give an account of the cos t s of technological processes and to analyse them economically. Primary and secondary processes are together named basic processes. These have an impor tant role in proce ss planning and manufacturing programming. In our example the quality of a certain machine construction is determined b y the proper spatial relati ons and dimensions of the surfaces of parts in the ove rwhelming majority of cases. Thus, from the aspect of quality, a geo me trical hierarchy of parts can be enforced in dissecting the processes in the first place. Accordingly, the following steps can be separated ( see:Fig.4 ) : • operation group i s that phase of the whole working process in which a certain part, starting from the rough piece, obtains its finished configur ation suitable for assembling and to which some mach inegroup (manufactu ring sys t em ) can be allocated in general; • operatio n is that in which on e of the cha racteristic configurations of the part having a common symmetry ( shape d - group ) is machined and to this, on the basis of symmetry, some kind o f universal machine tool type ( a homogeneous mach ine tool group) can be allocated; • suboperation ( partial ope ration ) is that in \Jhich one of the shapes (su rface groups ) of a given configuration is ma chined and a typical set-up method a nd a clamping device set of common basis are attached to this; • operation element is that in which only on e surfaCe of a ce rt ain shape is machined according t o given dimension pa ra mete rs and tolerances and to this some kind of tool t ype and tool path can be allocated.
• momentum is such a ch ange of state which, in the geometrical sence, yields forming surface elements o f a pre sc ribed quality and cutting parameters are attached to thi s . The enumerated hierarchical decomposition included only details of the different phases of the primary pro c ess but the realizing means allot able to them were also marked. The latters refer to the possible variety of secondary and auxiliary processes connecting with the different levels. The se co - ordinations co ns titute the base of process planning. Theoretical models A signi ficant part of practical and organizational requirements i s formulated in the form of exact criteria f o r organizing the automated technologcal systems in a hierarchical way. The general requirements of the models valid for any level are as fol l o ws: • Boundary surfaces of s ubsy s tems have to be defined in suc h a manner that the connecti ons and streams thr ough them should be expressed by means of mathematical ( l ogic al and arithmetical) variables. • Structures of subsyste ms have to be synthetized in such a wa y that their common functi on ing can be described, on the base of independent diSCiplines if posSible, by laws and constraints treatable mathematically. • For the subsystems such optimum criteria should be interpreted which obtain a complete conditions sys tem by means of optimization of the sys tem above them. Fulfilment and concretization of the requirements enumerated above depend on the adequate disciplin e applicable in the first place. In the part manufacturing exemplifying discontinuous processes these are as follo\Js: -- operations re sea rch for ma nufacturing -- theor y of ope rati ons sequ ences -- mechatro nics for machine tools -- cutting theor y. Through the stepping we relate to a pos sible hierarchy of the system-models. We have to deal with the general requirement o f optimization in mo re detail. Technological opti miz ati on Universali t y o f the problem r esults from the fact that no specia l science can avoid optimum pr ob le ms if it derives its product s from aims of soci al origin. Th ese have also long appeared in several methodological disciplines independently ( "Mathe matical Pro g r a mmi n g", " 0 per a t ion s Re s ear ch", " Oeci sions Theory" ). Technical pr oblems can be divided into two large groups: • Technological pr ob lem s : all the possible processes of a given sys t em existing phySically have a subset whi ch includs realizing possibilities of a product described in some kind of modul structure. From them we must select t hat process varian t \Jhich is most sui table for prescribed ai m exterior to the system. • Oesign problems: all th e possible models o f a system of specific kno\Jledge existing in th oug ht have a subset which includes realizing possibilities of a function
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Thus, \·Ie need: • va ri ables (x), logical or a r ithme t i cal values of which a r e sel e ct a ble a nd r ealiz ab l e independen t ly of one a nothe r ; • functio ns or r elat i ons (M(x)) whi ch a r e interpreted by means of the vari a bles and given by the t ools i ndependen tl y o f the pr oblem; • functions or relations (A(x)) wh ic h a r e interp r e t ed by means o f the va r iab les and give n by the pr oblem ind e pe nde n tl y of the too l s;
224
T. Toth a lld I. Detzb
• a function U(x)) \,hich can be interpreted by means of t he va riables and it is de termined by the external aim independ ently of both the tools and the problem . Solution of the optimization prob l em, gen eraliz i ng the symbols, can be formulated as fo ll o\/s: 1. XT ' totality of the technical field of knowledge has to be assumed, a vector of whi ch, x t XT , \
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Fr om the scheme it is easy to see that not the optimum - searching procedure itself, de noted by the last (5th) step, i s primarily significant from the point of view of so lution, but com posin g those sets, ~hich have to be created in the previous steps. In the Fig. 5. the v isual models of one-level and of multi - level optimIzation are demonstrated. (In the interest of simplici t y feedback is not denoted. ) . An example from cutting techn olo gy The most up-to-date systems which represent high technology in production enginee ring are connected with cutting as a basic proce ss. In Fig.6, as an example, we have summarized th ose characteristics by means of ~hich the classes of technological systems can be identified. Alon!J the secondary and auxiliary processes essentially similar kinds of level s can be se parated on the basis of the models suitable for specific functions. Especially we empha sized i mportance of the addi tive objective function which comp reh ends the . obje ct iv e funcllon hiearchy of systems. For the sake of a uniform technological aspect we also propose to take into account the objective costs by additional equivalent times computing with the hourly cos t s of the direct environm ent. va li dity set of so lu hon variants
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REFERENCES William s, P.J.(1985) . Com puter Integrated Manu=facturing (C IM ). A Man agament Perspective. Ryerson Poly technical In stitute, Toronto. ( Draft papers). Buzacott,J.A. (19 82). Th e Fundamental Pr in ciples of Felexibility in ~anu facturing Systems . Proceedings of t he 1st International Conference on FMS, Brighton, United Kingdom. Office of Technology Assess ment ( OTA ) Report ( 1984 ) . Compu ter i zed Manufacturing Automation . ( Employment, Education and t he Wor k~. Congress of The Uni ted States, Washington. Kusiak, A. ( 1985 ) Flexible Manufacturing Systems: a Structural Approach. Internati onal Journal of Production ResearCh, Vol. 23, pp. 1057 - 1073. Yeomans, R.W., Choud r y,A.., and ten Hagen, P.J.~ . ( 1985 ) . Design Rules fo r a CH1 System . Ilo rth-Hol land, Amsterdam. ( cont.)
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tems, s umm arizi ng th e Fig . 6. Intern al hierarc hy of part ~ a n ulacturing s ys the cutting pr oc es s es of case the in cs teristi charac ant import most Primro se , P.L., and Le onard, R. ( 1986 ) . Identi fying the Flexib ility of FMS System s . Procee dings of the 26th I n ter in nation al Machin e Tool DeSign and Research Confer ence held in Manch ester. Dept.o f Mech. Engng. , Uni versit y of Hanche s ter Institu te o f Scien c e and Techno log y in Assoc. with MacMi llan Publis her s Ltd, pp.167 -173. Scheer ,A.-U . ( 1987 ) . CIH:De r comput erge steuer te Indust riebet rieb. Spri nger Verlag , 8erlin - Heidelb erg-Ne w Yo rkLondon -Paris- Tokyo. Schuy,K .J. ( 1987 ) . IBM Strateg y and Direction 3. Mainz (Draft paper) . Detzky ,I. ( 1988 ) . Manufa cturing Te c hnology 11. Theore tical Part 1. Educat ional Publis her,Bu dapest (in Hungar ian ) .
Toth,T . ( 1988 ) . Com puter Aided Proc ess Plannin g in Manufa cturi ng Te chn o l ogy . Doctor al Disser tati on f or Hunc ar i a n Academy o f SCienc e s , Budape s t ( in Hungar ian ) .