Title: Multi-response quality improvement by non-parametric DOE methods

Authors: George J. Besseris

Addresses: Department of Mechanical Engineering, Technological Education Institute of Piraeus, P. Ralli and Thivon Avenue 250, Aigaleo 12224, Athens, Greece; Advanced Industrial & Manufacturing Systems, Kingston University, London Surrey KT1 1LQ, UK

Abstract: Quality management principles promote the systematic elimination of problematic areas of products before they reach the marketplace. It is a rare fact that a product is as good as optimising just a single quality trait of it. A practical and economical method is presented in this work for placing statistical significance on non-linear multiresponse-to-factor relationship during screening experimentation with unreplicated and saturated fractional factorial designs. A technique is developed on a simple additive rule for multiple ranked responses all of which are tested synchronously against a group of product or process parameters. The developed hypothesis is tested based on the multi-level nonparametric method proposed by Jonckheere-Terpstra. Advantages exhibited are the minimal computational effort and convenience in usage while relaxing strict normality assumptions. The theoretical developments are illuminated by a case study on a recently posed problem in the ever-popular area of small-component plastic injection moulding.

Keywords: quality optimisation; design of experiments; DOE; non-parametric testing; unreplicated fractional design; robust design; multi-response quality improvement; productivity; quality management; plastic injection moulding.

DOI: 10.1504/IJPQM.2009.023699

International Journal of Productivity and Quality Management, 2009 Vol.4 No.3, pp.303 - 323

Published online: 08 Mar 2009 *

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