Abstract
In today's world there is increasing emphasis on personal style and individuality, and hence a preference for semi-finished, customizable products over finished products. Consequently, sales of do-it-yourself products are increasing, including the high-quality equipment necessary to complete semi-finished goods. A representative example is the sewing machine; sewing machines must have high process yield to keep after-sales service costs low. In the current paper, a key component of sewing machines, the upper axle bearing, is used to present an implementation of Six Sigma via the measure-analyse-improve-control (MAIC) approach. Four bearing characteristics are identified as being critical to quality and are used to develop process capability indices for evaluating bearing quality. Then, a multi-characteristic product capability analysis chart (MPCAC) is used to identify and analyse the factors affecting bearing quality. Finally, the results of experiments and statistical tests using control charts to identify the optimum process levels are presented. The results show that the MAIC approach will help manufacturers and suppliers of sewing machines achieve Six Sigma quality.