Transfer Function of Assembly Process with Compliant Non-ideal Parts

Abstract

Efficient modelling and analysis of geometric variation is crucial for quality control of assembly processes with compliant parts used for example in automotive and aerospace industries. Since most current computer-aided design (CAD) and Variation Simulation Analysis (VSA) systems are based on ideally sized, ideally located rigid or compliant geometry, they are unable to accurately model or predict the effects of variations in parts, fixturing and joining. This results in product failures due to un-modelled interactions between Key Product Characteristics (KPCs) of parts/assemblies and Key Control Characteristics (KCCs) of assembly process. Therefore, it is important to develop a generic variation simulation approach for assembly processes with complaint parts which will take into consideration non-ideal part geometries as caused by fabrication processes.This paper develops the Assembly Transfer Function (ATF) approach to model and simulate assembly process with compliant non-ideal parts. The proposed ATF is developed as an integration of three critical response functions of assembly process: (i) modelling non-ideal parts and its response to part fabrication errors; (ii) modelling n-2-1 fixture and its response to non-ideal parts; and (iii) modelling part-to-part joining process and its response to n-2-1 fixture. The ATF is developed in three steps: (i) use of the aforementioned three individual response functions; (ii) sampling of individual response functions; and, (iii) integration of the three response functions into an overall assembly process transfer function with capabilities to directly map input KCCs to output KPCs and ultimately to key performance indicators for assembly processes with compliant non-ideal parts. The developed ATF is demonstrated by using an industrial case study of automotive door assembly with remote fiber laser welding joining process.