Linking Process Capability to Cost In a Wire Drawing Plant

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This thesis represents work done in assessing the capability of a wire drawing production process. A data collection sheet is used to record the diameters of samples. Two sets of data are taken for the assessment. The procedure starts with checking for normality, verifying statistical control and finally determining the process capability index. The first observation gives process capability ratio, Ppk of 1.55, sample mean of 3.686 mm and sample standard deviation of 0.0525 mm. A Ppk of 1.37, sample mean of 4.099 mm and sample standard deviation of 0.0925 mm are obtained from the second observation. Determination of quality costs on the production line is discussed and an approach to quality costs analysis is developed and illustrated. A quality cost model for this line incorporating prevention, appraisal and failure cost elements is presented and validated using MatLab codes. The outputs of both observations suggest that the process has higher external than internal failure costs. The modeling concept developed could offer a general framework for most wire drawing industries in Ghana.
A Thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the Degree of Master of Science in Mechanical Engineering, September-2012