Fuzzy application in tolerance design

Tolerance design has always been a challenge to the designer. On the one hand, tight tolerances often imply good quality. On the other hand, the tighter the tolerance specification, the higher the cost of production. To achieve a proper balance between the two is not an easy matter. In this paper the authors examine a means of balancing these two conflicting requirements. A new tolerance representation based on fuzzy arithmetic has been proposed to allow for more intuitive and natural way of expressing relationships between different parts. With this representation, relative assembly tolerance constraints can be easily expressed. An assembly-driven fuzzy tolerance generation and assignment process is discussed. During the generation phase, fuzzy tolerance conditions are automatically generated through a feedback evaluation process. In addition, manufacturing process characteristic and cost considerations are integrated into the tolerance design process. Algorithms for performing the generation and allocation process are given and simulation is performed on a prototype feedback system. This prototype system is implemented on a Sun Sparcstation using C++