Company Size and Work Organization in CNC Machining

Copvright © IFAC Design of Work in Automated l\Ia n ufacturing Systems. Karlsruhe. Federal Republic of (;ermany I <)H~

COMPANY SIZE AND WORK ORGANIZATION IN CNC MACHINING A. Sorge,* G. Hartmann,* M. Warner** and I. Nicholas** */lIlallllliollll/ I I/.\Iilllli'

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Abstract . The paper reports results from a comparison of computer numerically controlled machine applications in Great Britain and West Germany. This has dealt with the manpower qualification and organization aspects of CNC and its different methods of programming . It is shown that the distribution of quali fications and organization are no direct result of technology. They follow from the strategy of a company designed to meet certain socio- economic challenges , and from culturally established training and organization patterns in the respective countries . Finally, a particular logic of CNC application during the present time is put forward to guide systems design and company strategy. Keywords . Computer organization ; machine tools ; man-machine systems; manufacturing processes; numerical control; production control; programming control.

INTRODUCTION

findings . First , we present results on the variance of control systems, organ izatio n and qualification patters within the two countries . Then, we summarise Anglo - German differences. As conclusions, we finally put forward a systematic view of how CNC may be geared to currently prevailing socio economic challenges in many countries.

During 197 9 - 8 1 , we conducted an investigation into the impact of computer numerica l ly controlled machine-tools on the organization of workflow and o n qualifications of the workforce. Research consisted of case studies in companies in Great Britain and West Germany , and data were collected by interviewing workers , engineers , managers and employee representatives according to a semi-structured guideline, and by analysing available personnel and technical data. The companies had been selected to fo r m pairs, consisting of one British and one Germany site, matched according to numbers of people employed , average size of batches in parts production, nature of parts in production , and composition of production equipment (extent of CNC use, types of cutting and control systems) . The study was geared not only to explain , within the respective countries , the variance of organization and qualification patterns , but also to compare these between the countries , in the matched pairs.

WORK ORGANIZATION AND QUALIFICATION STRUCTURE UNDER CNC All ou r results serve t o stress the extreme mall eability of CNC techno logy . There is no effect of CNC use as such. But this is not to say that technology is unimportant . Its importance only unf o lds in a continuous series of piecemeal modification and innova tion. This is part of a complex pattern of socio- technical design and impr ovement , where technical development interacts with organization and manpower development. We have found some solutions t o CNC app lica tion which are organizationally simple and some are complex; some emphasize functional differentiation and others integration of functions within positions or departments; there are both far-ranging polarisation of skills and qualifications as well as enrich ment of skills on the shop floor . Neither of these contrasting policies are more " advanced" from the technical point of view . Yet, it cannot be said that CNC application is idiosyncratic or accidental .

Twelve companies were investigated in total , half of them in each country . These included un i ts with large batches (over 1000) and sma l l ones (under 100) , sma l l units (under 100 emp l oyees) and large ones (with around 2000), and applications of CNC in turning, milling and drilling were studied . Results were reported , in detail, in Sorge et al . (1982, 1983). The interested reader i s asked to refer to these texts for mor e specific information . Here , we give an overview of

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A. So r ge

Ther e are very c l ear logics of CNC applica ti on , ins t ead of on l y one; these different l og i cs are a nalytical l y distinct; t hey in t er act a nd some t imes conf l ic t with each o t her. We tr y to distingu i sh the fo l lowing logics , b ut we admit tha t they are a lr eady c r ude syn th eses of different facto r s :

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Pl ant si ze · b urea u cra \ lsa l lO n 01 programming

Regar ding company or plant size , we have fou nd that small plants make a very u n conven t io na l use of CNC and maintain unbureau cratic , simple organisation . Programming re l a t ed functions are less concentrated into specia l ised departments or positions. There is no systematic apprenticeship training in t he plants , but a lot of pragmatic and flexible l earning in how to use CNC best . I n l arge r companies , more systematic procedures a nd grea t er division of labour have the con seque n ce of differentiating programming func tio n s away from the workshop , into spec i al ized departments . "H igh technology " by no means signifies g r ea t er bureaucra t isation; the smaller plants combine a striking l y h i gher p e rcentage of CNC machinery with weak forma l methods of o r ganisation , and a great deal of tradi t ion a l e n trepreneurial and intuitive s t yle , where as the bigger plants are som e times prevented f r om l arger scale CNC use by conventional organization of a more bur e aucratic type . Whilst the bigger p l ants are starting to in corpor ate CNC into apprenticeships and other ~ra i n i ng schedules in a more systematic way , this happens unconv e ntionally in the smaller p l an t s . Wh il st p l ant size is linked with a greater d i fferentiation of programming functions into sepa r ate departments, increas i ngly batch s i ze is linked with greater differen tia t ion of programming away from machine opera t ing , but not necessarily into separate departments . Nor is it necessarily taken away from the machine; there is a strong in clination fo r programme i nput on the machine , no t by the operator, but by a programmer , foreman , or setter , in small companies with l a r ge batches . This is the case of an un bureaucratic , but polarising division or l abou r a nd qua l ification structures . Increas i ng p l ant size is l i nked with the f ir st , and increasing ba t ch size with the second . They i nte r ac t t o br i ng for t h pa t te r ns of organi z ati o n and qual i fication i n the fol l owing way :

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1 ) Company or plant size 2) Ba t ch size , or time needed to machine a batch 3) Type of cutting and machinery 4) Nationa l institutions and habits of technica l work , management , and training 5) Socio - economic conditions of the present s i tuation , regarding shortage of natural resources , limitation of mass markets , and slow growth.

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Skills polarisa tio n and Bur e aucratisation of Pr ogramming under CNC

This scheme tr a ces mor e o r l e s s "id e alt ypical " s o luti o ns , ar o und which var i o us modifications occur in wo rking practice. But it helps t o summari se r e s u lts which show that polarisation o f f uncti o ns and skills is v e ry cl o sely link e d with batch si z e . This makes s e ns e in a simple wa y: The smalle r batch size i s , th e gre at e r is the need for frequ e nt c o nversi o n of machin e s to new tools , fixtur e s , a nd p a rts programs , and the less is ma chi ne - setting e xpertise differentiated fr om oper a ti o n. Ba tch size economies of s c al e thu s inv o lve a r e duction of skills at the o per a t o r l e v e l . Machine-setting and pr o gram-r ela ted func t ions ov e rlap , s o that e l i minati o n of setting from machin e o p e rati o n als o ent a i l s differentiation o f pr ogramming-r e l a ted functions from o perati o n , and it is ofte n linked with a f urth e r di ffe renti a ti o n between setting and p rog ramming . The ideal - typica l v a ri a ti o n d e scribed abo ve is modi f ied b y type of cutting pr o cess and machinery . This r e f e r s t o a wid e f ield o f differen c es r eg ardi ng numbe r s a nd type s o f tools , fixtur es a nd ma t er i al s , geome trical complexity o f co n tours, sta nd a rds of pre cision , and type of mac hin e . Ge ner ally , the more tim e it t a kes t o c o mpile a pro gram , th e mor e is p r ograrrmli ng di f fe r e nt i at e d f rom op erating , s o that it c a n o c c ur par a llel to it. The central r e as o n f o r d i f fer e ntiating programming and o per a ting b e ca us e o f complex ity of too ls , fixtur es , and c utting sequences and geome tri e s , is the desire to achieve maximum utulis at i on of ma chinery by way of programming and planni ng the next job while the previou s o n e is b eing pro cessed . This applies , abo v e all , t o machin ing - centres , particularly horizontal machin ing - centres . Here , differentiation o f planning and opera ting is , however , not necessarily very polarising , since skilled o perato rs are used on machining - centr e s , b ec ause o f high costs

Compa n y Organization ~n CNC Machining of machine, tools , and materials. On the othe r hand , less skilled workers are used on simpler milling machines without continuous path control. But because of this greater simplicity , operating and programming are less differentiated in this par t icular case. Tim e needed t o make a program is a central factor which is linked with different allo cations of programming - related functions. This means less programming on the shop floor and by the operator , the more time it takes to make a program . However, such a relationship presupposes that an ope rator cannot make a program without the machine being idle. But this is only true to a limited extent. We have seen cases of operators drafting programs after working h ours , at home. It is also possible , on some machines , to compile the program for the next job while the previous one is being processed . On the other hand , this requires that the operator can be relieved from frequent work - piece handling or other tasks wh ich reduce his ability to concentrate. The allocation of programming t o groups of personnel is thus not ob jectively given. It is influenced by technical advance of elec tronic contr ol and programming , as well as operator programming skill. Both of these are , however , subject to company or depart mental strategy . Geometrical or informatical problems are increasingly made easier and quicker to solve , which reduces programming time continuously , on the basis of a part with a given design complex ity. This holds , above a ll, in turning. With this tendendy , there is thus an increasing propensity to let operators engage in programming - related functions , from cu tting speed and feed modi fication up to program compilation on the shop floor. To that extent , advance of CNC is de-polarising with regard to previous NC methods. Its precise impact , however , has to be determined on the basis of a before- after assessment whi ch takes into account that CNC is penetrating into processes where previous techniques were a ls o linked with little polarisation , just as it is penetrating into processes where it is polarising skills and differentiating the organisation to the same extent as plug board o r cam - contr o lled machines. ANGLO-GERMAN DIFFERENCES Just as CNC has different effects according to plant and batch size , and type of cutting and machinery , so it also adapts to different societal environments. It is fitted into dif ferent institutions and habits of technical work , management , and training . In our cases , it leaves Anglo -German differences in this respect intact. The German companies distin guish less than the British ones between careers and departments for product i on management and production engineering , work

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planning and work execution functio ns. With regard to CNC , this means that in the British companies , both CNC operation in general as well as programming-planning functions are more limited to certa in groups or departments , whereas in the German com panies , participation in programming -r elated functions is more common to various groups of personnel and departments . There is conSistently greater use of shop floor and operator programming in Germany . This applies both regarding the select i on of equipment which is particularly appropriate for this purpose , the utilisation of control system variants , as well as deliberate training , manning , and organization poli cies. This CNC - specific difference ties in with noticeably different qualificat ion structures which stress the craft worker apprenticeship to a greater extent in Germany. The greater separation of program ming and opera ti.ng in Br i tain ti es in with the increasing differentiation of technician and worker apprenticeships , whilst technician training in Germany is invariably sub sequent t o craft worker training and ex peri ence . Whilst in Britain, the pla nning and programming function is distinctive of white - collar status , it is much less so in Germany , where blue - collar workers are mo re extensively used for programming both on the machine and in the planning department , and where rotation between the two cou ld be observed . National differences interact with company and batch size specific differences : in Germany, the similarity between organization, labour , and technical practices of small and larger compan i es is greater t han in Britain , where there appears to be a split between pragmatically flexible small plants and organizatio nally more segmented larger plants . Formal engineering qualifications at various l evels are more dist inctive of larger plants in Britain , whilst small British plants are often untouched by them . In Germany , however , formal qualifications are common t o small and larger plants a like. In both countries , however, the perception p revai led that CNC operation was less dis tinctive for requiring inf o rmatics skills than advanced machining skills. Programming aids on the machine or in the planning depa rtm ents are seen t o be tools of increasing facility which help to control a process which has become ever more demanding from the point of view of preCision , machining speeds , tools , fixtures , and materials . The control and program compilation element of CNC operation i s not an end in itself . The programmer is increasingly less of an "i nformation worker " by h i s working goa l and the skills and interest of his trade . Not only the system of control has changed , but

A. Sorge et aZ.

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also tools, materials, and cutting techniques. These remain, as ever, the focal point in machining. Control of more advanced mechanical processes is rendered possible by NC and CNC, but it remains the mechanical process itself which brings forth working problems and attractions alike. Such types of expertise and involvement are incorporated into the tasks of personnel groups with different emphases. Whereas the planner or production engineer assumes it to a greater extent in Britain, it is the craft worker who is more widely recognised to hold it in Germany. This difference is not specific to CNC, but represents a longer history of organization and training practices which is closely linked with social stratification. CNC technology is also moulded by this history. STRATEGIES TO MEET SOCIOECONOMIC CHALLENGES The logic of CNC application which is common to Britain and Germany, extends from macroeconomic factors, marketing strategies, through equipment choice and justification, to production engineering and organization, training and personnel policy. It therefore spans a very broad range of factors which influence enterprises, and upon which enterprises exert influence themselves. It can be argued that this common logic is inherent to the dominant strategy of companies which underlies the utilisation of CNC. This strategy may be more explicitly stated or more implicit; but its actual points of reference are remarkably similar from one company to the other. First it is generally mentioned that in slow or absent economic growth, enterprises are keen to cater for increasingly small market niches rather than for homogeneous mass markets. More individualised, customised products, and a greater number of product variants are thus required. Product innovation is part of this development, which leads to increasing numbers of parts and variants of parts in production. Market expansion or maintenance of market shares is only thought feasible with increased production variety. In product and parts design, there is a tendency for increasing complexity of parts. The acceleration of total product complexity increase can be checked if individual parts and components are designed to be more complex. This means a noticeable increase of geometrically more demanding cuts, and of the number of cuts of different types to be performed on a workpiece. Such a trend is both dependent on, and causal to, the wider diffusion of NC machining. Justification of NC machines thus has a qualitative element, not only one in terms of productivity. The kind of complex and precise cutting which is

made possible by NC machines, would often not have been possible with conventional machines, except if highly specialised and costly tools would have been used. This type of justification is often central, although it is difficult to express it quantitatively. Complex design of parts is linked with NC application in general, but greater variability of parts and products is more specifically linked with CNC application. Essential factors which make for increasing CNC application within the overall NC area, are - the need for more frequent and less timeconsuming conversion from one batch to another, which arises from increased variability of parts and products; - the need to reduce work-in progress in stocks and intermediate stores, which tend to grow rapidly when the full productivity of modern CNC machines is made use of, and when larger batches of a given workpiece are produced. Both market-oriented as well as working capital considerations thus point in the direction of smaller batch size and more frequent conversion. These are not only induced by developments over which the company has no control; they are also deliberately planned. This increased variability of batches cannot be handled through an increased vertical division of labour. It implies increased variability right at the level of the machine and the operator; every CNC operator is likely to have to deal with a greater and more frequently changing range of jobs. Part of this logic then is the increased flexibility and decentralisation of electronic control, by which more flexible change-overs and improvements of programs can be achieved. The crucial bottle-necks are not felt to be pure information-processing and calculating skills, but immediate experience with tools, materials, feeds, speeds, faults, and breakdowns. Skills in tackling such problems are most directly developed on the machine, and it can be seen that wider-ranging CNC application therefore entails a greater deal of programming and program-changing in the workshop or by operators. CONCLUSIONS It is against the background of socioeconomic tendencies that a statement about the general evolution of work under CNC can be made: where more frequent conversions of machines and smaller batch sizes are aimed, both - the development of electronic control systems, - the use of available variants of control, - and production organization, favour less polarised skills.

Company Organization in CNC Machining Thus , companies incr easing ly recognise the merits of an approach wh i ch rel i es strong l y on craft worker skills. A de-polarisation of skills and qualifications struc t ures is therefore within the present logic of CNC development and appli cat ion. This is not because it it a necessary consequence of CNC , but because CNC is developed and applied following a socio- economic context v..hich links eco nomi c success with de - polarisation. Hence derives the renewed interest in companies , particularly in Germany, to train and employ skilled workers . Increas ed programming o r program - changing in the workshop also signifies an assimilation of status for b lu e - and white-collar workers. Planning and programming activities are less constitutive of status distinctions when th ey are rendered easier. It would , however , be misleading to interpret this as another step towards the " post- industrial " society , "information-processing " work , or "service " functions , as of t en happens. Whilst it is true that even workers deal with increasing ly sophisticated information technology , this only concerns the tools of their trade rather than their working goals . It can be observed that greatly advanced e l ec tronic control and data - processing leads to strik ing sav ing s of add itiona l personnel engaged in planning , production control, and programming functions. Again, this follows from characteristics of the prese nt socioeconomic context : there is a need to expand t echnica l development and marketing efforts , which raises white-collar staff levels ; but in the production area , the growth of in directly productive employees is l eve l ling out . Fr om the po i nt of view of both , meeting current economic challenges through innova tion , reduc ed wo rk-in-pr ogress and capturing smaller market niches as well as meeting social demand for more satisfying work , systems design , manpower training and organi zation of workflow will have to come to arrangements which generalise the inv o lvement in programming. This entails a reduc tion of qualificational differences between workers and technicians , speCialists and the line hierarchy: We suggest that orientation of different actors - government , companies , unions , training bodies - has to follow such references if employment in economically viable companies in manufacturing is to be maintained or expanded , and if human l y mean ingful and satisfy ing opportunities of work are to be provided . REFERENCES Sorge , A., G. Hartmann , M. Warner , and I . Nicholas (1982). Mikroelektronik und Arbeit in der Industrie. Erfahrungen beim Einsatz von CNC -M aschinen in GroBbritan-

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nien und der Bundesrepublik. Campus , Frankfurt a.M . Sorge , A., G . Hartmann , M. Warner , and I. Nicholas (1983) . Mi c r oe lectroni cs and Manpow e r in Manufacturing. Applications of Computer Numerical Con tr o l in Grea t Britain and West Germany. Gower Press, Aldershot .