165 DATACOMMUNICATION FOR QUALITY ASSURANCE AND QUALITY MANAGEMENT IN COMPUTER INTAGRATED INDUSTRY M. Numan DURAKBASA, P. Herbert OSANNA, Rudolf OBERLANDER (Vienna University of Technology - T.U.Wien, Austria) Keywords: Quality management, co-ordinate metrology, quality control, CAD-CAM ABSTRACT The use of CAD and CAM also puts new demands on inspection and testing in computer integrated production processes. For the time being, computer-assisted quality control basically relies on computer-aided co-ordinate measuring techniques. In this environment new demands are put to quality management using the aid of computer assistance. INTRODUCTION In the last few years, because of its universality, the coordinate measurement technique has to an increasing extent assumed importance in mechanical manufacturing technology. By means of computer aided co-ordinate measuring machines it is possible to measure workpieces of a geometrically complex form accurately, objectively, and quickly. These instruments are particularly usefull for the solution of special measurement problems in precision mechanics. Since the early seventies higher standards for co-ordinate measuring machines have been developped. The implementation such devices into systems of computer integrated manufacturing allows for a regulated and automated production of workpieces of practically any kind of complex geometry such as can be produced with modern CNC machine tools today. In general sophisticated measurement techniques, among other things, are considered a most crucial requirement for the production of industrial goods of a contro!led, and optimized quality. Data communication between measuring devices and computer network combines the various tasks of the interaction between inspection, evaluation and construction, as there are: planning of measurements, generating of measuring programs, management of workpiece and stylus exchange, evaluation of measurement data. With great flexibility this results in an accurate and wastefree manufacturing. 166 NATIONAL AND INTERNATIONAL STANDARDS The past fifteen years have seen a continued increase in importance of computer aided measurement techniques as a means to control modern production engineering /1/. At the same time, the regulations governing product design and manufacture have undergone basic international harmonization; focal pOints of interest included deviations in form and position /2/, as well as workpiece microgeometry /3/ and tolerancing principles according to the principle of independence /4/. In many countries, these international standards have been adopted, almost without modification, also on national leve! similar as the new international standards about quality assurance and quality management /5/. . In the past the development of measurement techniques was long overshadowed by the big advances made in machine tool manufacturing since the early fifties, especially in terms of automatization and measuring speed. In this field, NC- and CNC-techniques have brought about an extremely high level of automation at a comparatively early point in this development aiming at a fully automated production cycle. For, more than any other processing equipment, CNC machine tools with continuous-path control nowadays make possible the industrial production of workpieces which can only be checked by means of computer assisted co-ordinate measurement techniques. METROLOGY IN COMPUTER INTEGRATED PRODUCTION The use of the new technologies CAD, CAP and CAM also puts new demands on inspection and testing processes. For the time being, computer-assisted quality control (CAQ) basically relies on computer aided co-ordinate measuring techniques (CMT). As an example take free-form surfaces, which defy measuring, unless computers are used. In this case the co-ordinate measurement equipment used establishes a com· puter network with links to all production phases, thus assuring the direct transmission of data. By way of analogy, this is also how most different and diverse components of construction are measured; typical examples are gears, profiles or bladelike forms. The development of com,Puter controlled multi-co-ordinate measurement equipment (CMM - co-ordinate measuring machine) has test ylied control units, which can be used not only for accurate measurements of workpiece dimensions in any direction but also the reliable measurement of the shape and position of almost any complex workpiece feature. Thus, a Single, universally applicable instrument has made it possible for us to check and control nearly each and every aspect of workpiece geometry. 167 However, the use o'f computer assisted multi-co-ordinate measurement techniques as part of the pr~duction requires such indepth knowledge and practical experience as we have not yet gained for the most part. For, beyond our basic knowledge of technology, we have to further penetrate into this independent discipline until 'h 3 have arrived at its specific fundamentals. Three-dimensional measurements, huge amounts of data at our immediate disposal, the definition of clear-cut systems of reference: taken together, these trends provide engineers with additional know-how in production technology and function-tolerance limits, making mechanical testing equipment a thing of the past. Last, but not least, CNC co-ordinate measuring instruments have turned representative production testing into an economically justifiable investment. By using CMT techniques we are for the first time in Cl position of integrating highly automated inspection systems of great flexibility into the production cycle. A!so, it has to be pOinted out that the above-mentioned development has only begun. There are a couple of improvements which are as necessary as likely to occur in the near future. True, those stages of the production cycle concerned will face and efficient measuring techniques that yield measurement data of high accuracy and reliability, will remain. MODERN MEASUREMENT TECHNIQUES In modern production engineering, quality assurance comprises two major procedures: process control and quality control. As the emphasis lies on the prevention, rather than the detection, of inaccuracies, comprehensive knowledge of all processes and techniques involved becomes a conditio sine qua non. Quality assurance then stands for ttle recording and analYSis of the necessary data, and the proper presentation of the informations obtained in a form analogous to the questions initially posed. Computer aided CMT has been used in industrial production since the midseventies. Since then, they have increasingly gained importance, and broad application, not least because of thE! head-over-heel development in the field of microcomputers. At this moment, international as well as national standards (see /6/ to /91) for CMT are being worked on by technical committees of competence. EspeCially the completion of the relevant projE!CtS for international standardization is likely to take some more time. 168 TOLERANCES AND NECESSARY ALLOWANCES There exist a series of influences that must be taken into consideration working on data communication between construction and measurement techniques. It is gene, ral knowledge to take into account ISO tolerances /10/ and general tolerances /11/ respectively for linear dimensions. But also geometrical deviations of form and position /2/ must lie within certain limits whereas general tolerances /12/ or tables of experimental values respectively /13/ can help the designer when he has to specify the allowances on drawings. Workpiece accuracy is also affected by surface roughness and therefore it is necessary to specify parameters respectively in drawings. Because of the overall workpiece geometry there are demands for workpiece manipulating. Different parts must be fed into the measuring instrument and changed for measurement taking into consideration the demanded consequence respectively. Dependent of the workpiece shape it is also often necessary to variegate the stylus geometry and configuration. MEASURING DATA COMMUNICATION FOR QUALITY ASSURANCE In the last few years much research work was done in the field of data communication in production. Many technical articles have been published. References /14/ to /20/ make an optional selection of the comprehensive literature. Special solutions are described in technical journals and proposed from various producers of measuring devices respectively. Nevertheless there is still an increaSing demand for flexible and accurate budget-priced systems in this field. CAQ/CAD data communication combines the various tasks of the interaction between engineering, construction, inspection and evaluation: • set-up of workpiece geometry in respect to geometrical tolerances (dimensions, macro and micro geometry), • choosing of economic allowances, • selecting of wc>rkpieces for inspection, • inspection plar ning in respect to identification and sequence of measurement, • generating of control data for automatic measurements. • considerations ,to avoid collisions between stylus and workpiece, • choosing of m3asurement control data, • management ef workpiece and stylus exchange, • transfer of mecsuring results, • analysis and statistical evaluation of measurement data. 169 • correction feedback. For all these tasks clnd problems the interfaces to CAD systems are very important. possible the linking of the various modules of the complete The interfaces mak(~ system (Fig. 1). Fig. 1: CAD/CAQ interfaces The interfaces are rated dependent on different criteria: • formati~lg of data, • structuring of data, • temporary or permanent storing of data. There exist interfacE!s for databanks, programming, graphics, users and dclvices. For CAD/CAO linka!Je all informations of the technical drawing must be taken into consideration. In principle the geometrical informations of the workpiece respectively are needed. For CA.D/CAO data communication it is more useful! to define a comprehensive product model instead of a geometrical model by including measurement oriented informations.For ttle measurement of free form surfaces /21, 22/ under the condition of CAD/CAO data communication co-ordinate metrology is of basic importance. For standard workpiece features such as planes, spheres, cylinders etc. the vectorial tolerancing and dimensioning /6, 7, 8/ must be taken into consideration. CAD/GAO datacomrnunication for quality management in computer integrated production is possible on the basis of co-ordinate metrology (Fig. 2). 170 Fig. 2: Configuration of CAQ/CAD data communication C:JI\SHUCT ON A\JD MEASURit\G LA30R,t·TORV PRODUCT ION - ~-=': -' Ii- -r I 1,1: I !,::' ·- - . I "'"1200 UMO,S 1I , ~ -1 t;!~,IO . Select :U , ,I = 11 :~ I i Me~v -·IT ! HP ~ '-.. - 91336/16 -.~ r:=-~ , - 17=;:; DESIGNER / . Acceptcrce ACOM~ . 36 /20C -~_/: YD.·, - _ ~:t III 11" I I Fcrmot _~ ;- - __ _________ "< Trans: er of Sur t:Ke - l;ato in ~-T, : -----------[ r------DA T COMPUTER l~ I . Co--,s ICvet ,on L:_~ ~ ,----~l ! CO";'UR~: Pl_M~\)!NG ,::AD - l ~-l L______ ~ C'J ~A"' U T~ I .. ___ j i " (IiOS·T - COVIPUlt:R) - - - -.. - -------' Of'; - LINE COUl-'vNG A measuring cell for the flexible automation of measurement and quality management in small industrial plants for precision mechanics was drawn up at the Vienna University of Technology. A local area network of several personal computers for the various tasks in this connexion and for cell contra! is linked to a small high precision CNC-CMM. The measuring cell incorporates also an industrial robot for work piece manipulating and an automatic probe changer to exchange stylii of the CMM. Other measuring devices for roughness and form measurement are included in this data communication system and there are also links to data banks for production , calculation, construction and quality data.The application of the proposed measuring cell guarantees automatic inspection and economical manufacturing. CONCLUSIONS The proposed concept can be seen as a further step with the goal to achieve accurate and automated inspection and quality management in computer integrated production on the basis of low budget systems. Besides linking of the CMM and the various computer systems it is also essential to provide for communication with data banks for geometrical allowances. With great flexibility this results in an accurate and wastefree production. 171 REFERENCES: /1/0sanna, P.H.: They Measure the Position and the Dimensions. Europa industrie revue 16 (1982), No.1 , pp.17/20 /2/ISO 1101: Technical Drawings; Geometrical Tolerancing; Tolerances of ~orm , Orientation, Location and Run-out. Generalities, Definitions, Symbols, Indications on Drawings. 1983 /3/ISO 4287-1: Surface Roughness - Terminology - Part 1; Surface and its Parameters. 1984 /4/ISO 8015: Technical Drawings; Fundamental Tolerancing Principle. 1985 /5/ISO 9004 - 1987: Quality Management and Quality System Elements - Guidelines. /6/ISO/TC3/WG10 N39: Dimensional and Geometrical Co-ordinate Measurements. Part I: Terms,Definitions. Geometrical Fundamental Principles. Code of Practice. May 1988 /7/0N M 1380: KoordinatenmeBtechnik. Geometrische Grundlagen. Grundlegende Benennungen und Definitionen. 1988 /8/DIN 32880, Teil 1: Kordinatem~chk Draft Standard, Dec. 1986 . Geometrische Grundlagen und 8egriffe. /9/ANSI/ASME 889.1.12M-1985: Methods for Performance Evaluation of Coordinate Measuring Machines. 1985 /10/ISO 286-1 : ISO System of Limits and Fits - Part 1; Bases of Tolerances, Deviations and Fits. 1988 /11/ISO 2768-1: General Tolerances ; Tolerances for Linear and Angular Dimensions Without individual Tolerance Indications. 1989 /12/ISO 2768-2: General Tolerances ; Geometrical Tolerances for Features Without Individual Tolerance Indications. 1989 /13/0sanna, PH.: Deviations and Tolerances of Position in Production Engineering. Wear Vol. 109 (1986), Nr. 1/4, pp.157/170 /14/Jacoby, H.-D.: Kopplung von Software fUr KoordinatenrneBgerate mit CAD/CAMSystemen . VDI-Bericht Nr. 540 (1984), pp.53/70 /15/Modrich , G.: Wirtschaftlich fertigen aut einem flexiblen Fertigungssystem. tz fUr Metallbearbeitung 78 (1984), No.2, pp.2/5 /16/Breyer, K.-H., 8ehrendt, K., Lynch, T: Datenverbund 2:wischen CAD/CAM-Anlagen und KoordinatenmeBgeraten . ZwF 80 (1985) , No.11 , pp.477/479 172 /17/Pfeifer, T.: Qualitatssicherung in der rechnerintegrierten Fertigung (CIM). VDI-8ericht No. 606 (1986), pp.1/24 /18/Sostar, A.: Einsatz von KoordinatenmeBgeraten in flexiblen Fertigungssystemen. International Conference: Modern Production and Production-Metrology, T.U.Wien, April 1986, 14 p. /19/0hnheiser, R.: Neue Funktionen in der Datentechnik. IMT-Symposium, C.Zeiss, 1987,35 p. /20/0sanna, P.H., Durakbasa, N.M., Kappis, G., Oberlander, R.: Concepts and Strategies for CAD/CAQ Data Communication of a Flexible Measuring Cell for Precision Mechanics. VDI-8ericht 761, 1989, pp.43/48 /21NDA-Flachenschnittstelle (VDA-FS). Richtlinie des Verbands der Automobilindustrie e.v. (VDA) , Frankfurt, 1988, 30 p. /22/Garbrecht, T, Steger, W., Klein, H., Wilhelm, M.C., Georgi, B., Pieper J .: Entwurf einer Schnittstelle. wt Werkstattstechnik 79(1989), Nr. 5, pp.274/276 AUTHORS: Dozent Dr.techn. M.Numan DURAK8ASA, Univ.Dozent Or techn. P. Herbert OSANNA, Dr.techn. Rudolf OBERL.ANDER, Department for Interchangeable Manufacture and Industrial Metrology (Austauschbau und MeBtechnik) at the Institute of Production Engineering, Vienna University of Technoiogy (TUW), Austria. A-1040 Wien, Karlspl. 13/3113