Structure and Application of a Universal Company-Independent Data Bank for Tools

Prof. Dr.-lng. Dipl.-Win. Ing. W . Eversheim (I), Dipl.-lng. S. Jacobs (*), Dipl.-ing. L. Wienand (*) Received on March 3, 1987 - Accepted by the Editorial Committee

Abstract: llmufacturing industry has a considerable need for data concerning tools and tool applica- tions. A company-indepecdent data bank for tools containing centrally-stored, up-to-date and objective data is therefore currently in course of development at the Laboratory for Hachine Tools and Produc- tion Engineering (UZL) at the Aachen University of Technology. The data bank will permit rapid exploitation of newly-development tools by industrial users and stimulate innovation in the tool development field. Apart from establishing parameters for the complete description of tools and for the description of potential combinations of individual modules, the project necessitates development of an appropriate data structure. This may be used as the basis for a company-specific tool data bank, forming the core of a tool management system. Key words: Cutting tools, tool selection, tool modules, combination rules, tool data bank, tool dnta

structure

1. Introduction

In the era of CIM (Computer Integrated Manufacturing), information processing has become a key factor in modern manufacturing. Despite numerous attempts at solving the various important problems involved /1-9/, management of often expensive tooling has typically remained a gap in the overall information flow of many companies. Difficulties commence with the purchase of replacement tools or the search for new tools to match new machining tasks. The multiplicity of tool variants and characteristics makes it difficult for the user to gain a comprehensive view of the market and its characteristic features IFig. 1).

In the Federal Republic of Germany alone there are, for example, no fewer than 184 cutting tool manufactu- rers, offering up to twelve groups of tools. In an extreme case, twenty thousand or more potential tool- module combinations result for each process.

Manufacturer-specific documentation and terminology are further obstacles to adequate market transparency. The characteristics and potential combinations of individual tools, not to speak of the comparative merits of different makes of tool, are therefore fre- quently less than clear to the user.

In consequence, performance reserves of modern produc- tion equipment remain unexploited and tool inventories are kept unnecessarily large.

In order to obtain a complete up-to-date conspectus of available tools and their characteristics, individual

companies would need to create and maintain extensive collections of data, a task which is scarcely within the bounds of economic feasibility, especially for small and medium-sized firms.

A non-company-specific data bank for cutting tools is therefore currently in process of development at the WZL. This central data bank enables the following objec- tives to be attained:

- rapid transfer and exploitation of newly-developed

- improved exchange of information between tool manu-

tools,

facturers and users,

- increased market transparency, - encouragement of trends towards standardisation, - a stimulus for the development of innovative tools.

In order to derive the greatest possible benefit from the data bank at an early stage, the processes tur- ning, milling and drilling were taken into account in data preparation. These processes represent 81 % of all machining and some 8 6 . 6 % of the total value Of cutting tools produced in Germany.

The data bank user needs to be assisted by user- friendly procedures in order to facilitate handling of the complex questions involved in different types of planning task. These should be adapted to the diffe-

1971 - 0 . 6 b l l l . DM 1986 4 2 , 6 b I l l . I)((

o f stored tools

0 machining problms with 0 lack of msslbllttles h-cost metal cutttn

Fig. 1: Reasons for the Creation of a Company-Inde- pendent Data Bank for Tools

(1) Member of the Directorial Board of the Laboratory rent information requirements, planning goal for Machine Tools and Production Engineering (WZL), existing knowledge of the user. Technical University of Aachen; Head of the Planning and Organisation Department of the Fraunhofer Insti- This system requirement necessitates systematic tute for Production Technology (IPT), Aachen. sification of the available tools.

( * ) Collaborator of the Laboratory for Machine Tools and Production Enqineering ( W Z L ) .

. s and

clas-

Annals of the ClRP Vol. 36/1/1987 321

2 . Tool Systematisation

National and international institutions are endeavou- ring to systematise and structure production processes and associated tools in a fashion consonant with their great importance for industry.

Standards have, for example, been laid down by the German Standards Institute (DIN) and recommendations issued by the Association of German Engineers (VDI). DIN 8580 and DIN 8589 are partly devoted to the clas- sification of uroduction processes. Classification

milling is for example possible with plain milling cutters, end mills, face mills, shell end mills or side and face milling cutters / l l / .

Standardisation of tools, on the other hand, is limited to determination of the shape and dimensions of the tool. No system analogous to the process clas- sification is in existence.

This situation lies led tool manufacturers to coin a variety of different names for identical tools. in industrial practice, names derived from the superfi-

features are as follows:

aain group

cia1 appearance of the tool gain currency, making the systematic comparison needed for selection of suitable tools more difficult.

classification according to variation in shape ma- For the purpose of creating the tools data bank, tools terial properties; were therefore categorized into groups (Fig. 2 ) . Be-

Fiq. 2: DerivatLon and Structure of Groups of CuttingTools

Group

Sub-group

Sub-group

Sub-group

Whereas the first three ~~ ~~~ ~

still be regarded as representing a consistent syste- matic approach, uniform comparative description of all production processes is no longer ensured after inclu- sion of the fourth and fifth features.

type of variation: ginning with the tool type, tools are specified stage by stage. The primary classifying feature for milling

chiefly according to the tool tools is the type of tool holding fixture required, employed; e.g. milling cutter with shaft or milling cutter with

attachment hole. surface to be produced:

Within this group, a distinction is drawn between various different classifYin9 standard cutters, form cutters and special cutters. features / l o / . Cutters for special applications, e.9. ring mills, are

specially identified. levels of classification may

Apart from this inadequacy of the classification sys- tem, the form of process classification used is unsui- table for tool selection purposes, since planer

In addition to conventional one-part tools, system tools, which are rapidly gaining ground, have been taken into account. Fundamentally, a tool consists of a number of tool modules. If these are integrated in a single tool, the result i s termed a one-part tool, e.g. an end mill with cylindrical shaft as defined in DIN 8 4 4 . A tool assembled from a number of independent tool modules is termed a system tool.

Fig. 3 : Specificatlon for the Descriptlon of Cutting Tools and their Interfaces

322

An assembly of tool modules stored as a single entry is referred to as a complete tool. When such assem- blies are entered in the data bank, tool-internal interfaces such as that between the cutting edge and cutting edge carrier are omitted. The smaller number of parameters is, however, associated with a conside- rably larger number of complete tools to be recorded, since each combination of modules needs to be stored. Separate recording of individual tool modules proved more advantageous in this respect, providing greater flexibility in the combination of modules into tools and facilitating substitution or addition of new tools and modules.

A systematic approach was therefore developed to per- mit automatic interlinking of tool modules as they are entered. To this end, it is necessary both to assign tool parameters to the modules and to derive new parameters describing potential module combinations (Fig. 3 ) . These interface parameters must also be conditioned in such a way that rules can be used to assign matching modules to one another reliably.

This form of interlinking in place of rigid combina- tion by means of identification numbers enables single modules or complete tools to be selected automatically by describing a specification profile or by inputting fixed sub-components for which suitable partners are to be found. Assembly dimensions are then generated on this basis. When a new module is added, it will suf- fice to formulate the appropriate rule. In order to interlink the same module by means of identification numbers, all possible combinations would need to be entered and stored.

3 . Data Bank Concept

The constraints implied by systematic tool classifica- tion impose requirements on both the data bank model and the data bank concept.

The data Eramework of a tool may be sub-divided into general, technological and geometrical data and graphic information (Fig. 4 ) . These are supplemented by combination indicators for tool modules.

Fig. 5 shows how the data structure is derived in the' case of a cutter. The geometrical data are sub-divided into data relating to the whole tool, data concerning

- Inconsistencies in the data are avoided.

An analysis of the tool selection procedures used by companies reveals two fundamental search strategies which are also facilitated by relational data struc- tures. In the first case, a tool of a particular type is sought. In the second, tools are selected by speci- fying special constraints. Both types of query must be allowed for in creating the user interface of the data bank [Fig. 5).

Direct searching enables the field of search to be narrowed down progressively. The categorisation of tools into groups illustrated in Fig. 3 is used to specify and generate the search instruction. The more precisely the field of search can be described by the hierarchical selection stages, the smaller and more specific the number of suitable tools identified. Direct searching yields a number of similar tools either at the tool group or at the tool type level.

The term indirect searching refers to the formulation of a tool specification profile matched to a particu- lar processing or planning task. The following groups of criteria are available to the planner:

- type of processing, - processing parameters, - tool/cutting material properties,

- workpiece material properties, - cutting parameters. As there is no hierarchical relationship between these criteria, a relational data structure is also suitable for this planning application. The number of applica- tion parameters selected enables the field of search to be narrowed down. An indirect search yields a number of similar tools which fulfil the prescribed application parameters.

The two types of search may be used in combination. The relevant tool spectrum can first be narrowed down by means of a direct search, and the remaining tools further specified by entering the application parameters.

Tool- Genera I Technological identification Data Data

Fig. 4: Derivation of Data Structure

the cutting section and data describing the shank section. The shank is described by the parameters shank type, shank form, type of taper and shank size. During realisation of a relational data model, the relevant data for a highly-specialised shank type can, for example, be stored in a readily-understood shank- dimension relation.

Gene.-ally-speaking, a relational data structure has the following advantages for the present application:

A user-friendly interface assists in generating the search instruction. The menus guide the user through the programme, minimising input effort. The selection process can also be facilitated by the optional display of graphics giving information on the tool types.

In general, the planning sequence can be suited to the individual needs and knowledge of the user. Utilities such as sub-menus can be used, or levels of the hierarchy can be omitted or selected directly.

- Each shaft configuration and its physical data are Before the data bank system can transfer the results described only once. of a search to the user, the form of output must be

determined. The content, scope and presentation of the - New shaft configurations can be added quickly and data can be specified. The output of results can thus according to an easily-understood procedure. be suited to the specific demands of each group of

- The amount of data to be stored is reduced. users.

323

The free generation of the search instruction, the reduction of repeat groups of modular tool elements and the potential tool combinations impose severe demands on the data bank system, posing complex problems which only a relational data bank is able to solve.

4 . Operatinq the Data Bank

The company-independent tools data bank is intended for use by a large number of tool manufacturers and users. This form of use and the large volume of data involved require central data storage and a host computer, in which the conceptual pattern and internal pattern of the data bank are resident. Data users are provided with an independent programme representing the external data bank pattern (Fig. 6 ) . Data communication is via Datex-P within the public telephone network. Datex-P is characterised by its traffic-volume oriented structure, high data-transfer reliability and high performance duplex connections. There are no restrictions on the type of hardware employed. These features enable the data bank to be accessed from anywhere in the FRG and from abroad.

It is necessary for the data bank operation to be organised in such a way that the independence of individual tool manufacturers and users is protected. The form of organisation must also ensure technologi- cal competence (Fig. 6 ) . The most important task of data management is to control data access, input and updating. Tool manufacturers are entitled both to access the data bank and to modify their own data. Users have data access only. Data input is by means of an input programme and a PC, providing automatic checks for formal errors, plausibility and complete- ness. Updating of manufacturer-related data is decen- tralised and i s carried out by the manufacturer con- cerned, using the same routines as for data input.

The requirements for integration of the data bank in the operational environment are thus satisfied.

5 . Internal Integration

The company-independent data bank for tools is intended to supplement rather than to replace company- specific tool management modules. It constitutes a

Fig. 5: Strategies for Creating the Request Instruc-

general pool of information supplying data to company- internal files or data banks.

Almost all planning sectors of a company may be expec- ted to make use of the data bank (Fig. 7). Only the strategic level will remain relatively unaffected, due to the specific nature of its planning tasks.

Against the background of job-specific information needs and differing levels of user knowledge, which

tion

Fig. 6: Data Management Organisation

affects the appropriate search strategies and desired planning goals, the system concept permits alternative forms of use.

The system allows, for example, specific solutions for concrete processing problems, which can be realised rapidly during production equipment planning. Another planning objective assisted by the system is the ex- tension of the decision base to safeguard investment decisions. In addition, the tool stock can be updated by cyclical or acyclical technological innovation searches. The technological data groups discussed in Section 3 are available for thise purposes.

Business and stockkeeping data are limited to general delivery data such as "in stock, not in stock" and possibly catalogue prices. Other delivery and price conditions are extremely manufacturer- and user-speci- fic, and constitute individual supplementary informa- tion for the company-independent data bank. CAD data sets may be similarly regarded. As these are not so far available in standardised form, they should be kept separate from data bank management. In the fu- ture, an information network could be created between

f producer specific \

int8rnaI tactical level data eXChEng0

I

I

operational level

I I

Fig. 7: Communication and Data Transfer for the Com- pany-Independent Data Bank for Tools

the neutral data bank for tools and manufacturer- specific supplementary files, since such data sets are already partly available with the manufacturers.

The results of a data bank search are evaluated by the planner and released for transfer to the company- specific file or data bank. The data extracted from the tools data bank may be supplemented by company- specific data, forming the core of a company tool management system.

Company-specific supplementary data may, for example, include :

- presetting data, - correction data,

324

- current wear data, - individually-negotiated terms of delivery, - company-specific classifications, - storage location, etc. In general, use of the data bank thus initiates a data flow, as exemplified by the case of process planning.

Within the framework of day-to-day process planning, company-specific solutions are found for current pro- cessing jobs by accessing the company-specif1c tool file (Fig. 8 ) .

For processing problems due to

- product changes, - material changes, - tool fracture, etc.

! I Process Planning I I

Fig. 8: Integration of the Company-Independent Data Bank for Tools in Internal Planning Proces- ses: Example - Process Planning

A non-company-specific solution is additionally pos- sible with the aid of the data bank for tools. The search information again consists of a tool specification profile.

The tools data bank supports not only short-term plan- ning of this kind, but medium-term planning in the methods planning sector. Decisions on new and replace- ment investment to update and standardise the company- specific tool potential can be safeguarded by tool innovation searches. The company-specific tool poten-

- - I K.231 company specific toot potential 2; development of the market potential ,%%I k Information deficit En f externat Influences

tial, which at present often falls well short of the available (job-specific) market potential (Fig. 9). can be individually matched to current tool develop- ments by use of the tools data bank. In addition, procedures for skipping hierarchical search levels in potential matching searches can be made smoother and continuous company development encouraged.

These measures are to be seen as part of a total package for improvement of the productive factor "in- formation". In association with the materials and cutting materials information provided by INFOS, patent and literature data banks, etc., the tools data bank provides the user with a comprehensive pool of information for solving cutting technology problems.

Conclusions

h p i d and reliable selection of suitable tools both for day-to-day process planning and for short- and medium-term investment decisions is assisted by an improved flow of information between tool manufactu- rers and users. The paper presents a concept for the structure and applications of a company-independent tools data bank intended to support this information flow. The data bank described encourages standardisa- tion aimed at reducing tool inventories and supports increased use of innovative tools. The pool of infor- mation provided facilitates access to new markets for small and medium-sized firms.

I____

References:

/1/ Balbach, J., Rechnerunterstutzte Rationalisierung des Werkszeugwesens in Betrieben mit spanender Fertigung kleiner Serien, Doctoral Thesis, University of Hanover, 1983.

/2/ Giusti, F., Santochi, M . , Coats: An expert module for Optimal Tool Selection, CIRP-Annals, Vol. 35/1, 1986.

/ 3 / wesch, H . , Systematisierung und Optimierung der Fer t igungsrn i t te lauswahl fiir die Drehbearbeitung, Doctoral Thesis, RWTH Aachen, 1983.

/ 4 / WestkBmpfer, E . , Reorganisation des Werkzeuqwc- sens, Industrie-Anzeiger 99, No. 86.

/5/ Richter, R., Rechnerunterstutzter Leistunqsver- gleich fUr spanende Maschinenwerkzeuge, Ferti- gungstechnik und Betrieb, Berlin, 3 0 , 1980.

/6/ Ley, W., Entwicklung von Entscheidungshilfen zur Integration der Fertigungshilfsmitteldisposition in EDV-gestutzte Produktionsplanungs- und -stew- rungssysteme, Doctoral Thesis, RWTH Aachen, 1985.

/ 7 / Tonshoff, H. K., Balbach, J., Rationelie C.rgar~i- sation des Werkzeugwesens bei spanender bleinsc- rienfertigung - Werkzeugplanung, ZWF 78 (1983) 3 .

/8/ Vutz, J., Entwicklung einer Auswahlstrategie far den Einsatz von Fertigungsmitteln bei der Fras- bearbeitung in Einzel- und Kleinserienfertigunq, Doctoral Thesis, RWTH Aachen, 1986.

/9/ Storr, A., Mayer, J . , Walker, M., Werkzeugorgani- sation mit Schnittstelle zu Fertiqungsleitsyste- men, WZ Zeitschrift f i i r industrielle Fertigunq 76 (1986).

/lo/ DIN 8589, Part 3, Aug. 1982.

/11/ Konig, W., Fertigungstechnik, Vol. 1, VDI-Verlag, Diisseldorf, 1981.

Fig. 9: Methods of Adapting Market and Company Tool Potent ia 1

325