Optimal tolerance design of mechanical assemblies using finite element simulation and intelligent techniques

Abstract

The technological and financial limitations in the manufacturing process are the reasons for non achievability of nominal dimension Therefore tolerance allocation is important in assembly CAD CAM CAE integration plays a major role in tolerance allocation It utilizes the required functional characteristics and manufacturing cost of the product which had a great impact on determination of the process method, machine tooling set up and process sequence of the part in the processing plan In a mechanical design geometric and dimensional tolerances are used to specify the range within which a part geometry and size may vary while conforming to the functional requirements Assigned tolerances have a direct effect not only on the machining costs but also on the product quality Unnecessarily tight tolerances results in high production costs yet the tolerances should ensure that the functional performance requirements of the products stay within a satisfactory range Tolerances which are too loose can affect the product quality and increase the scrap rate and production costs In general designers allocate tolerances for parts based on their experience and on handbooks and standards which may at times lead to certain errors Computer Aided Tolerancing Design has become an important research direction in integrated CAD CAM CAE systems