Tolerance Stack Analysis for Assembly

Abstract

Studies have indicated that design for manufacture and design for assembly have a significant impact on the success of a product. One of the key issues is tolerance specification and thus it is important for the designer to consider tolerance analysis thoroughly in the early stages of product development. With minor modifications and if used properly, tolerance charting can be a valuable tool to the product designer. This paper illustrates two methods used to tackle tolerance balancing for assembly and provides an insight into the considerations to be taken into account. A manual method first demonstrates the fundamental concepts while a computer aided version further enhances the charting process. The latter is easy to apply and renders greater flexibility during problem formulation. Consequently, what–if analysis is possible and thus better results can be achieved. However, it should be cautioned that tolerance charts are merely tools; the results they produce can only be as good as the inputs they receive and thus a ‘perfect’ solution cannot be guaranteed. Nonetheless, tolerance charting is an effective diagnostic tool as it provides tolerance analysis in the early stage of products development.