Simultaneous tolerancing for design and manufacturing

TLDR

The paper highlights shortcomings of conventional tolerancing and introduces simultaneous tolerancing as a new theory to address these gaps. The study aims to introduce simultaneous tolerancing theory and an interim tolerances method for concurrent engineering design. The authors develop a general mathematical model of optimal tolerancing, discuss worst‑case and statistical approaches, and propose interim tolerances to guide machining processes. The theory enables direct determination of optimal machining tolerances, reducing manufacturing cost and improving product quality, as demonstrated by a practical example.

Abstract

This paper presents a new tolerance design theory—simultaneous tolerancing— which works in the concurrent engineering context. After stating the need to develop a simultaneous tolerancing theory by showing the shortcomings of conventional tolerancing technique, the concept of simultaneous tolerancing is given, and its elements are briefly presented. Then we focus our attention on the development of a general mathematical model of optimal tolerancing supporting concurrent engineering. Two commonly used models, worst-case and statistical, are discussed in detail. Next, a method of 'interim tolerances', which help to determine an appropriate machining process without using functional tolerances, is proposed. The simultaneous tolerancing theory presented in this paper permits of determining directly optimal machining tolerances in product design, reducing the manufacturing cost and improving the quality of products. Finally, an example is given, showing that the proposed theory is feasible in practice.