Title: Performance evaluation of continuous production process by trapezoidal fuzzy process capability indices

Authors: Rahebe Keshavarzi; Mohammad Hossein Abooie

Addresses: Department of Industrial Engineering, Faculty of Technical and Engineering, Science and Arts University, 89167-13335, Daneshjoo Avenue, Yazd, Iran ' Department of Industrial Engineering, Faculty of Technical and Engineering, Yazd University, 89195-741, Pejoohesh Street, Safa-ieh, Yazd, Iran

Abstract: Process capability indices (PCIs) can be viewed as the effective and excellent means of measuring product quality and process performance. They are very useful statistical analysis tools to summarise process dispersion and location by using process capability analysis (PCA). However, they have some limitations which prevent a deep and flexible analysis because of the crisp measurements and specification limits (SLs). Fuzzy set theory can be used to add more flexibility to process capability analyses. In this study, the fuzzy X and MRX control charts are used to analyse the process of continuous production in terms of trapezoidal fuzzy numbers (TrFN). Also, fuzzy PCIs are produced when SLs and measurements are presented as trapezoidal fuzzy numbers. For this aim, a computer program is coded in MATLAB software. The fuzzy control charts are utilised in Yazd Fiber Production Plant. The results show that in continuous production processes, fuzzy measurements can yield a more accurate analysis. Furthermore, relying on the fuzzy capability indices, one can have a flexible analysis of the process performance.

Keywords: trapezoidal fuzzy numbers; fuzzy PCIs; process capability indices; specification limits; continuous production process; process capability analysis; PCA; fuzzy set theory; fuzzy measurements; fuzzy logic; control charts; individual observations; SPC; statistical process control.

DOI: 10.1504/IJPMB.2013.058161

International Journal of Process Management and Benchmarking, 2013 Vol.3 No.3, pp.371 - 385

Published online: 12 Jul 2014 *

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