Design for Tolerance of Electro-Mechanical Assemblies: An Integrated Approach

Tolerancing decisions during the design of electro-mechanical products profoundly affect cost and quality. Existing approaches t o tolerance analysis and synthe-sis entail detailed knowledge of geometry of the assem-blies and are mos t ly applicable during advanced stages of design, leading t o a less t h a n optimal design pro-cess. Dur ing the design process of assemblies, both the assembly structure and associated tolerance in forma-t i o n evolve continuously and significant gains can be achieved by effectively using this in format ion t o influ-ence t h e design of t he assembly. Motivated by this, we identify and explore t w o goals of research tha t we believe can expand the scope of tolerancing t o the en-tare design process. T h e f i r s t goal is t o advance toler-ancing decisions t o the earliest possible stages of de-sign. This issue raises the need for effective represen-ta t ion of tolerancing in format ion during early stages of design and for effective assembly modeling. T h e second goal addresses the appropriate use of indus try best practices and efficient computational approaches for tolerance analysis and synthesis. Pursu i t of these goals leads t o the definit ion of a multi-level approach that enables tolerancing t o be addressed at successive stages of design in a n incremental, cont inuous ongo-ing fashion. T h e resulting design process, which we call t he Des ign for Tolerance process, integrates three impor tant domains: ( I) design activities a t successive stages of design; (2) assembly models tha t evolve con-t inuously through the design process; and (5’) methods and best practices f o r tolerance analysis and synthesis. W e demonstrate ma jor steps of o u r proposed approach through a simple, ye t illustrative, example.