International Journal of Technology Enhancements and Emerging Engineering Research (ISSN 2347-4289)

IJTEEE >> Volume 2 - Issue 7, July 2014 Edition

International Journal of Technology Enhancements and Emerging Engineering Research  
International Journal of Technology Enhancements and Emerging Engineering Research

Website: http://www.ijteee.org

ISSN 2347-4289

Combined Control Scheme For Monitoring Quality Characteristics

[Full Text]



Adekeye K. S, Bada Olatunbosun



Keywords: Statistical process control, control chart, Exponentially Weighted Moving Average (EWMA), Exponentially Weighted Moving Variance (EMWV)



ABSTRACT: In the literature, the Exponentially Weighted Moving Average (EWMA) and Exponentially Weighted Moving Variance (EMWV) control schemes have been used separately to monitor the process average and process variability respectively. Here the two are combined and applied on simulated process with different level of variation. The control limit interval (CLI) and the average run length (ARL) were evaluated for the combined chart. The combined chart performed better than the two independently. Furthermore, an algorithm was developed for the two control charts and implemented on visual basic VB6.0. The obtained results show that the combined EWMA and EWMV control chart is very sensitive in detecting shift in production process and every shift in the process mean is always preceded by shift in the process variability.



[1]. Adekeye(2009): An Introduction to Industrial Statis-tics(Concepts and Practice). Revised Ed. Adewumi Printing and Publishing House, Ilorin, Nigeria.

[2]. Adekeye(2012): Modified Simple Robust Control Chart Based On Median Absolute Deviation. Transnational Journal of Science and Technology,May 2012 edition vol.2,No 4

[3]. Gupta, P.K & Hira, D. S(2012); Operational Research. S. Chand & Company Ltd. New Delhi.

[4]. Lucas, J.M. & Saccucci, M.S. (1990); Exponentially Weighted Moving Average Control Schemes: Properties and enhancement. Journal of Technometrics. Vol. 32, No. 1, pp.1-12.

[5]. Macgregor, J.F. and Harris T.J.(1990); Discussion of EWMA Control Schemes. Journal of Technometrics. Vol. 32, pp.23-26

[6]. Montgomery, D.G. and Masterangelo, C.M.(1991); Some Statistical Quality Control. John Wiley and Sons, New York, NY

[7]. Montgomery, Douglas G. (2001); Introduction to Statistical Quality control (4th Edition). John Wiley and Sons Inc., Canada

[8]. Roberts, S. W.(1959):”Control Chart Test Based on Geometric Moving Average“ Technometrics. Vol. 42(1), pp. 97-102.

[9]. Shewhart, W.A.(1931): Economic Control of Quality of Manufactured Product. D. Van Nostrand, New York, USA.

[10]. Stephen, B. V and Max, D. Morris(2011): Statistical Quality Assurance Methods for Engineers.