Global assembly quality methodology: A new method for evaluating assembly complexities in globally distributed manufacturing

Supplying high-quality products to markets is an essential mission of manufacturers. The recent globalization of mass production has led to lower prices for consumers and potentially higher profit for manufacturers. However, a lack of quality management across globally distributed manufacturing severely increases costs as well as negatively impact on a company's brand image.; Traditional quality control based on statistics theory has not provided any definite guidelines for dealing with assembly defects across globally distributed manufacturing including defects caused by mistakes. This dissertation develops a method for predicting assembly defect rates at pre-production stages: the Global Assembly Quality Methodology.; The complexities in assembly processes have a strong correlation with the occurrences of defects. This dissertation develops metrics for assembly complexity using two engineering measures: assembly time estimates and a rating for ease-of-assemble. The author collected extensive field data including consumer audio equipment assembled at various manufacturing sites around the world, and used defect data for validating the metrics. This dissertation develops the process-based complexity factor derived from a “time standard” defined for a set of assembly tasks and shows satisfactory correlation with defect rates for each assembly step. Further, this research developed a design-based complexity factor derived from the “Design for Assembly” method for evaluating assembly to augment factors not captured by the process-based complexity factor. Integrating these complexity factors not only improves prediction accuracy of defect rates, but also provides guidelines for improving the original design concept as well as each process steps.; The dissertation then demonstrates a procedure to implement the Assembly Quality Methodology for globally distributed manufacturing. The implementation of the methodology can help company executives make decisions on the manufacturing sites. The method also enables manufacturing engineers to take proactive measures for potential highly error-prone assembly processes and alerts product designers of deficiencies in the original concept.