Shalabar In particular, this paper will hernard the effects of tolerancing, thermal expansion and uncertainties of temperature in order to know if the uncertainties of temperature must be included in the tolerance chain or can be neglected as second order. The designer directly imposes four geometrical conditions: The corresponding body surfaces must then be lished on a case-by-case basis, which proves highly difficult for oriented S17 and located S This A procedure has been designed to scan all surface couples method has been detailed in [7,8]. In the CLIC system, positioning requirements are automati- cally generated, and the corresponding specifications are then 3. This paper will provide a method to decompose forging dies for machining planning in the case bernar high speed machining finishing operations.

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There are three main engineering process, which includes design, analysis, purposes: first, describe tolerancing process; second, analyze manufacturing and control. Nowadays, Information CAT systems, in order to understand its limits and its Technology vendors provide a various Computer-A ided usefulness in tolerancing task; finally, formalize the expected Tolerancing CAT systems which aid designer to address requirements of industrial grade in order to improve future tolerancing challenges.

Moreover, these systems are not always integrated into CAD systems. Each data used or generated during tolerancing tasks, how to one uses the data produced by the previous tasks and ensure traceability of tolerancing data during product generates another data for the next tasks.

Recently, the need for each expert to know how these results Key words: Tolerancing process, CAT systems, Product were generated has been raised. Especially, all informat ion as follows is required : Lifecycle Management, Process Engineering.

To improve their ability to launch products to market faster, and - Results and risk associated reduce products overall cost, they continue to improve their Currently, each expert has his own methodology in managing development process in particularly their tolerancing process.

Moreover, this task is carried out by into account as follows: several experts coming fro m different departments Designer, - Several CAT systems used for different goals; Manufacturer, Controller Therefore, effective capture of information, and its systems; extraction, recording, exchange and sharing become - Tolerancing process is not clearly defined; progressively important.

These lead companies to review and improve their methodologies in managing the exchange and - Tolerancing data is not managed properly by a data sharing information throughout the tolerancing process.

In the industry, tolerancing process often starts during This situation makes it difficult to ensure the traceability detailed design phase when product geometry is totally between all data used and generated during tolerancing defined Fig 3 , and therefore any modification of a part process, and therefore, between functional requirements and dimension becomes a very comp lex and an expensive task. Furthermore, it is very difficult to keep traceability between functional requirements and functional tolerancing.

Figure 3 Tolerancing process throughout Design process There are some existing approaches dealing with tolerancing task in the whole product process [T1, K1] survey papers. Ballu et al. Mathieu et al. Dantan et al. They suggest to begin tolerancing process early in the design process in conceptual stage and progressively all along engineering tasks, taking into account, product functionalities 3- Tolerancing task and tolerances Fig 4.

Basically, To lerancing consists in defining coherent dimensional and geometrical constraints to ensure a good product performance. Salo mons et al. Each task has a particular goal. Tolerancing specification is the task of specifying tolerances, defining the tolerancing types and related tolerancing values. Tolerancing analysis is a method which is used to verify the proper execution of the assembly after tolerances have been specified. On the contrary Tolerancing synthesis is an up-bottom approach which consists in determining tolerancing value of each part in order to satisfy a functional requirement.

Tolerancing verification defines inspection planning and metrological procedures for functional requirement in order to check the product conformity and to Figure 4 Integrated Tolerancing Process [D1] verify assumptions made by designers.

Each system is used for a special task in a specific stage of design process. In this section, the main CAT systems used in the current Figure 2 Tolerancing process tolerancing practices are analysed. It has In spite of being fully integrated CAT systems use only offered to designers a scientific approach based on modelling geometric data based on DMU.

Then, designers have to and analysing. For tolerancing synthesis aspect, several CAT systems propose the possibility to identify main contributors, and therefore, the most influence link of a tolerancing chain. This Table 1. Each system covers a limited perimeter of language and display results regarding a specific design process Fig 5. Th is situation leads designers to structure which cannot be used or explored by use different systems in order to carry out their tolerancing another system.

For each expert, it is essential that the produced information should be easily availab le. Du ring preliminary design, the information produced should be documented simultaneously with tolerancing work and all the collected information should be recorded and capitalized in an integrated information processing system.

This information should easily used by other experts. In this way, an efficient collaborative working approach can be created inside the company between all experts involved in tolerancing process.

Thus, TDM system becomes progressively crucial for tolerancing task, and therefore for design task. TDM must be fully integrated in a PLM p latform to ensure the traceability of tolerancing data within product lifecycle.

Feng et al. Figure 5 CAT systems throughout design process Zhao et al. And therefore, it Product Lifecycle Management permits to carry out a complex assembly like a gear box in little t ime. The data must not focus on current needs but also on future industrial needs. Thus, it is very [A1] B. Anselmetti, Generat ion of functional tolerancing important to involve aerospace and automotive industry in based on positioning features, Co mputer-Aided Design, this work.

Therefore, current research work, international standards, [A2] B. Anselmetti, R. Chavanne, J. Yang, N. Anwer, industrial practices, scientific state-of-art, technological Quick GPS: A new CAT system for single part tolerancing state-of-art and new technologies should be considered. Co mputer-Aided Design, 42 9 : , Cost estimation related to tolerance specification is an [B1] A. Ballu, H. Falgarone, N. Chevassus, L. Specifications for Product Modelling.

Boag, D. Chamberlin, M. Florescu, J. Rob ie, J. Recently, several international standard data [BR1] G. Booch, J. Ru mbaugh, I. Anwer, and L. Integrated UM L remains a popular standard for expressing the tolerancing process for conceptual design.

CIRP Annals - product structure. It can be easily applied to the Manufacturing Technology, 52 1 — , Eynard, N Troussier. Carratt, PLM based development of software systems. Eynard, T. Gallet, P. Nowak, and L. At the present time, Workflow, Co mputers in Industry, 55 3 : , PDM systems do not support product data related to [F1] S.

Feng and Y. A dimension and tolerance tolerancing data which should be integrated in a future data model for concurrent design and systems integration. Journal of Manufacturing Systems, Vo l. Eynard et al. Khanafer, A. Desrochers, L. Mathieu, A. In: Proc. Mauchand, A. Siadat, J. Dantan, N. Perry : A The management of product tolerancing data within its proposal for decision-making system aiming to support lifecycle is one of the major problems not solved yet well cost estimat ion during the preliminary design, in Proc.

Salo mons, F. Haalboo m, H. Jonge Poerink, F. A computer aided tolerancing tool ii: To lerancing analysis. Co mputers in Industry, 31 2 — , Salo mons, H. Haalboom, F. A computer aided tolerancing tool i: Tolerancing specification. Co mputers in Industry, 31 2 - , Tich kiewitch, and D. Diverse aspects of tolerancing on an integrated design context. Zhao, T. Khethara Pasupathy and R. Modeling and representation of geometric tolerances information in integrated measurement processes.


Bernard Anselmetti





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