PRODUCAO Tool Management in Systems Equipped With CNC Machines

Giovanni Tani Dipartimento di Meccanica e Tecnologie Industriali - Facolta di Ingegneria Universita di Firenze - Via S. Marta 3 - FIRENZE - ITALIA

Key words: Tool file, Tool Card, Automatic Tool Selection

ABSTRACT This wolk has been carned out for the purpose ofrealizing an automated system for the integrated management of tools within a company. By integrating planning, inspection and tool-room functions, automated tool management can ensure optimum utilization of tools on the selected machines, guaranteeing their effective availability.

The first stage of the wolk consisted of defining and developing a Tool Management System whose central nucleus is a unified Data Base for all of the tools, forming part of the company's Technological Files (files on machines, materials, equipment, methods, etc.), interfaceable with all of the company departments that require information on tools. The system assigns code numbers to the individual components ofthe tools and file them on the basis of their morphological and functional characteristics. The system is also designed to effect assemblies of tools, from which are obtained the "Tool Cards" required for compiling wotking cycles (CAPP), for CAM progranuning and for the Tool-room where the tools are physically prepared Methods for interfacing with suitable systems for the aforesaid functions have also been devised.

Belo Horizonte, Vol 7, N" 2, p.177-187 Nov. 1997 177 PRODUCAo

1. Introduction tools are taken from the warehouse, prepared for , preset, reground or regenerated. While tool management is a particularly urgent need in FMS Within the sphere of Production installations, it is also becoming Systems, the development of the concept increasingly important in shops that of integration has subsequently led to produce small lots. Efficient planning and considering the integrated management control of production necessarily calls for of tools. Data on tools do not concern shop real-time knowledge of the situation of the procedures alone, but are absolutely production system, within which tools essential for establishing the working have an important role. cycle of a product and for programming machine tools to carry out the various In response to market demand, companies now produce highly operations. Some information, moreover, differentiated products. As a result, must also be made available to the manufacturing has become enormously company's management system.(Fig.l) more complicated and increasingly greater resources are needed to stay The objectives that may be attained competitive. One of these resources through the implementation of an consists expressly of tools, which have integrated TMS system include: now taken on significant weight also as - improvement in performance of the regards financial aspects. The complexity Production System of the tools, the performance level - high levels of machine utilization required and the great number of services - reduction in downtime demanded make their overall cost a major - optimum tool selection item in a company's accounts. - reduction in variety and number of tools used Frequently, moreover, the lack of - optimized industrial purchasing effective standardization of tools leads to - supplying tools to machines just in their excessive proliferation as well as time continuous modifications in the solutions involving the engineering adopted by the programmers of CNC department in the concerns of the shop. Machine Tools. When an integrated tool management For these reasons, specialized software system is adopted, changes must be made systems for the implementation of tool in many company procedures while at the management procedures (Tool same time each department involved must Management System - TMS) have been be encouraged to utilize the potential of introduced, starting in the 1980s. The first the system to best advantage. Correct applications were chiefly concerned with application of the system, however, can tool management on the shop level; here yield significant financial results very in fact TMS is utilized for "physical" quickly (in some companies the management of tools, both in the Store application of TMS has resulted, in less Room where tools for current use are than a year, in 30% and more reduction usually kept and in the Tool Room, where in the number of tools in circulation).

178 I iT~BI S ele ctionIC onfigunt. Simulating tool flow p E-B-{f. _. -1- L ~ \l / ~~O A C ~ N Cutting parameters Tool Schedules, capacity, .... N C Vo = +--+ Data Base 0 I (~) ap= f I j ::: N "- ..- -- N T G Checking tools Monitoring tool flow / ~ R .,!:) 0 ~- ~~o L '--' I I Store room I 1Toolroom 1 I I L r MANUFACTURING ) Fig! - TMS functions

2. The project File, utilizing a Data Base of the relational type designed to serve as single source of The objective of the work carried out information on tools and thus to be was that of designing a Tool Management utilized by all of the different users within System able to provide management of tools, perfectly integrated with the the company. Consequently, it must company departments involved in this contain a great variety of data needed by activity, more specifically with the the different departments. This file will Schedules and Methods Department and form part of the Company Technological the Shop Engineering Department, the Files, consisting of Processes File, Tool Store Room and the Tool Room, the Machine Tools File, Materials File, Industrial Purchasing and Accounting Equipment File, Manufacturing Sheets Departments. File, Cutting Data File, and will The project, carried out in several necessarily be interfaceable with them and stages, first calls for the creation of a Tools perfectly integrated with them. (Fig. 2)

179 PRODUCAo

Processes IMaterials IMachines ITools IMethods IFixture ICutting Data Teclmological Data - Bases ~~ IManufill:turing I Warehouse Tool- Room Enpeerin8 I I I Pro:ms I I I - Pro cess Planning - Pw:chasing - Defining working - Prep ering c orre ction cycle, data

- Scheduling - Storing - Def. assemblies - Setting up tools

- Machine, utili:J:won -Coding - Def. cutting data - Tools regeneration

- Sp are parts - Prep. theoretical - Prep. physical tool card tool card

Fig 2 - Utilizers of TMS The Tool Management System environment can be used to create Data developed, based on this file, can be used Bases of Relational type. to obtain the assemblies of tools and the Tool Card utilized in compiling work This Data Base was then implemented cycles, CAM programming and in the mechanical production "physical" preparation of tools in the Tool­ environment, and procedures for its rooms, ensuring correct rationalization utilization in C language were developed, and standardization of tool use. (Fig. 3) using within them SQL (Structured Query Language) commands for interface with 3. The Tool File and the TMS the Data Base. developed The functions provided by the system include: The structure ofthe data base utilized a) Organization and creation offiles is the standard DEC RDB (Relational for the representation of elements, Data Base), which in the VMSIUNIX association trails, fields of application.

180 b) Automatic generation of coding of f) Graphical representation of the elements to be linked to the analog individual elements and elements of a functions of the company management completed assembly. software. c) Manual or guided creation of the g) Generation of tool cards and assembly compositions and automatic monitoring of the elements utilized. generation of the assembly code number and of the geometric parameters of the h) Interface with the CAM system assembly. allowing transfer of assembly geometries and connection between the two d) Creation of trails with spare parts environments. and inserts. e) Identification of utilizations through i) Interface with the Tool Room technological research keys. Software.

Managing Elements

- tree structure -levels - variables CAM Inteface Managing Assemblies - dimensions - Tool-code - graphic. repro - UID codes - tool code - Composition - technology

Managing Tool Card Coding - Tool-code - Management - Correctors Program - Offset values Interface - Elements code - elements - dimensions - assemblies - tool card Tool Room Interface

Fig 3 - Functional diagram of TMS

181 4. File structure of object which is utilized in warehouse management of the Tool-Room software. Data regarding elements (tools, 3) FAMILIES: From this level on, the mandrels, accessories, etc.) are stored in work of grouping is carried out to meet the DB for subsequent processing by the the specific requirements of the company. program for the purpose of executing the In general, in passing from one level to various operations of association, search another, one or more characteristics of the and linkage necessary to enable the elements which are to be entered are required functions. specified. Accordingly, the organizer of the library is responsible for deciding The objective to be attained was that which properties of the object should be of classifying the elements according to evidenced starting from the "highest" criteria of grouping and subdivision into levels. levels, reflecting either the common or the specific nature of certain characteristics For example, after the group (type) of of the objects. Groups or sub-groups are cutters has been specified, a more thus established with the precise aim of detailed description is given which serves making the object immediately to identify the distinct sub-groups identifiable. (families), which are still very numerous; for example, there will be the family of Subdivision is obtained through a tree the face mills with inserts, the family of with 4 levels of grouping. This kind of the cylindrical end mills, etc. subdivision must be established by the user of the file, who will also specify the 4) SUB-FAMILIES: this is the last criteria for classification and grouping. level of grouping of elements and is obtai.ned by specifying, for each family, a In the case in question, the following partIcular combination of variables structure has been defined: ter~ed standardized. For example, cylm~ri.cal end mills in HSS for rough­ 1) AREAS: represent, as a general mach.mmg (as compared to the previously rule, the different processes in which a mentioned family, it is specified that the tool can be utilized or the different material is a super-high-speed steel and functions it can carry out. For example: the structural characteristics are designed milling, turning, components .... for rough-machining operations). 5) ELEMENTS : these are the 2) TYPES: for each area it is possible individual stored objects for which the to distinguish macroscopically between dimensional values and/or those of the integral tools (U), tool carriers (P), characteristics, previously associated with accessories (A) and so on. The letter an entire family, must be specified. While enclosed in parenthesis indicates the type the dimensional variables are of a single

182 type, the variables in characteristics, identify, in its entirety, the whole group always of alphanumeric type, mayor may of variables to be utilized for classifying not be pre-defined. the elements.

For example, cylindrical end mill in Basically, these consist of two groups: HSS for rough-machining f = 50 mm , Group I: the variables which height = 36 mm, construction DIN N, describe the properties of a set of elements coated with TiN. and which are thus managed in the "high" level description of the element. The examples described, taken from This group contains a single type of the structure which has actually been variables termed standardized. These are realized, are given exclusively for the pre-established by the organizer of the purpose of defining the means available library, who can thus furnish options, for organizing the file. "suggesting" the selection, Le., the value that they can assume. The standardized 5. Coding the elements variables serve to identify within a family the sub-groups having common The coding system adopted refers to a characteristics. An example referring to mono-code structure; since only the the family of cylindrical end mills with function of identification is required, the shell is the following: (Table I) code is as brief as possible. Moreover, this structure is in perfect accordance with the Group II: hierarchical scheme of classification used variables which describe in detail the for the management software packages morphological/dimensional with which it had to be aligned. characteristics of the individual elements. Accordingly, a 12-digit code of numerical In this group the following may be type was selected. noted: - normalized variables: The program can generate the code - numerical ( e.g., diameter, automatically and then transfer it to the working length, nO of teeth ... ) management Software, which is the - alphanumeric ( e.g., cooling, instrument utilized to control materials in supplier, denomination ofISO inserts ... ) circulation, including tools. they can also be grouped either with reference to a precise area or with genera1 6. Defining variables validity. - pre-established variables or types of Each element is described by a more attribute: or less complex group of variables. In these are utilized to furnish selection developing the system it was necessary to options a priori ( attributes ), thus facilitating data entry operations.

183 Standardized Variables Options 1. Specific type: a. helical tooth finishing cutter End Mill b. rough-machining chip breaker c. semi-finishing chip breaker d. with straight teeth for flattening ( XO =75)

e. with straight teeth for shoulders ( XO =90)

2. Construction a. type N (Mat. with Rs> 500mm2 ) characteristics

b. type H c. type W (Mat. with Rs < 500mm2 ) d. construction for stainless steels e. construction for titanium. 3 ...... a ......

Table 1

7.Characterization of - Derived from Standard families -According to Drawing. In the last two cases it will be possible to take from an SID family, en bloc, the In general, a company which produces set of variables already adopted, which can small lots utilizes commercially available then be modified or completed very tools, tools modified in respect to the quickly. "commercial" type and tools specially Tool-room management also requires designed for the production of a that at this stage a distinction be made detennined product. This distinction gives between groups of elements that are not rise to the following definition of tool perishable (e.g., toolholders for lathe or classes bodies of facing cutter with inserts), -Standard (STD) simple perishable elements (e.g., inserts),

184 and simple elements which can be reached the element of connection with regenerated or reground (e.g., tools made the machine it is possible to recall any ofHSS). other elements downstream such as hard metal inserts in the case of drilling tips It is then possible to characterize the with inserts or turning tools with inserts. families of compositions and of Association between two elements in assemblies, for the purpose of creating the composition of an assembly takes libraries of pre-assemblies or assemblies. place through the recognition of a The latter are then treated like any other common variable that describes the elements and grouped in families. coupling mode.

8. Assemblies module Since tools and toolholders are constructed according to international A simple tool such as a drilling bit or standards (UNI, DIN,ISO) all of the a milling cutter of any type cannot be dimensions of the object, in the specific mounted directly on the mandrel of case the connection devices, are known modern machines but beforehand. This is the typical case where requires, at minimum, a toolholder the library manager can create a pre­ equipped with fitting designed according established variable, i.e., a type of attribute to standards, ISO for instance. which for this application is denominated Upstream-Downstream Code (UID) . The need to perform particular machining operations as well as the use Each UID code is thus an attribute of modular components has complicated which, containing dimensional references relevant to the individual element, is still further the realization and assigned on the local level. The utilization management of these assemblies. of this type of variable makes it possible Accordingly, standardization of their to disregard the code numbers of the utilization which is recognized by both individual elements which, in addition to CAM programmers and tool-room being more numerous than the coupling operators is needed. When working cycles types, could never be pre-established and are programmed it is absolutely necessary thus would not allow automatic to establish exactly how the tool will be composition. mounted and what are the most important nominal dimensions. When the The assemblies are coded to form a assemblies module is enabled, all of the library, exactly as is done with single elements. The program module for them necessary components can be selected is enabled by selecting a family of semi-automatically. Starting from the compositions or assemblies. At this level basic element, i.e., the tool, all of the other it will be decided which standardized elements are selected upstream of it, variables, such as numerical variables or towards the mandrel. After having characteristics should be adopted.

185 PRODUCAO

Management of the numerical nucleus of the System, consisting of the variables calls for the creation of rules for tools Data Base, the DB management composition which allow, at the moment procedures and application programs when the individual assemblies are allowing coding of tools, filing of them, entered, automatic fetching of the the execution of assemblies and the numerical values of each stored element compiling of tool cards has then been to obtain the resulting data (from sums, developed and perfected, as described subtraction or evaluation of minimums above. Modes of interface with the Tool­ and maximums) of interest in the specific Room software and with the CAM application. programming systems have been devised.

9. Graphic representation Now in the stage of development is the "Technological Research" module for The system contains a program for the automatic selection of tools interfaced implementation of a library of graphic with a CAD-CAM features-oriented files in DXF format which represent the system, which will be used to select in a different types of tools with their basic simple manner the features to be geometry and dimensions. machined and thus to obtain directly from the pattern all of the necessary data for The standard format of the file also tool selection. allows for personalization ofthe graphics through the CAD system utilized in the A further step ahead will be that of company. In the case of assemblies, global developing a module for filing and graphical representation of the assembly processing of cutting data, in ord~r to is automatically obtained by recalling all associate to the selected tools the most of the graphic files of the individual suitable technological parameters which components belonging to the specific take account of the specific characteristics assembly. ofthe machining process to be carried out, and of the operating methods associated with machine tools, materials, equipment, to.Conclusions and and production criteria. developments Bibliography In the development of this work, the characteristics and architecture of a Tool KRAUSE F., KIMURA F., Management System have been KJELBERG T., LU S.C. "Product completely defined and operating modes Modeling"- Annals of CIRP K. P.,1993 have been established for its correct utilization within the company by all of VAN HOUTEN F.J. "Manufacturing the departments using tools. The basic Interfaces" - Annals ofCIRP K.P.,1992

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