Modelling robustness in serial multi-stage manufacturing processes

Abstract

The study of robustness in single-stage manufacturing has been explored by a large number of researchers and practitioners. However, modelling of robustness in multi-stage manufacturing using multivariate data is seldom used. The aim of this paper is to develop a methodology to model process robustness in a serial multi-stage manufacturing system. Combining statistical regression, Taylor series expansion, the root-sum-squares method and a variation model, the methodology proposes a measurement system for robustness. The resulting metric, while quantifying robustness, measures absorbed and transmitted variations across the stages of a manufacturing process. Using the methodology in a serial two-stage worm gear manufacturing process, the levels of robustness and both absorbed and transmitted variations are determined, thus identifying significant variations across manufacturing stages. The details of this application with the types of corrective actions as required for minimisation of process performance deterioration are presented.

Keywords:

• robustness
• multi-stage manufacturing
• transmitted variation
• capability indices
• worm gear manufacturing process

Acknowledgements

The authors gratefully acknowledge the kind support and cooperation provided by the management of the case study plant. The authors are also grateful to the learned reviewers for their comments and suggestions in improving the quality of the paper.