Expert rules for manufacturability analysis of misalignment defects during product design

The quality manufacturability (QM) of a design is defined as the likelihood that defects will occur during its manufacture in a standard plant. Clearly, some designs are more likely to have a lower production yield rate and/or higher quality management cost compared with an alternative design. The reason for this is that, in any production facility, there is an inherent defect occurrence process, the strength of which is dependent on both the product's design and process capability. This relationship between the defect occurrence process and the design is the basis for QM. In this paper, our focus is exclusively on the causes and evaluation of part misalignments. We present a set of expert rules that can be used to predict misalignment defects in assembled products. The expert rules were developed via an analytical simulation of the assembly process, and an investigation of assembly practice. The input variables to these rules are several design features or factors, while the output is the QM-Misalignment matrix. The different types of misalignment defects are introduced and labelled. An illustrative example is included.