Improvement in quality and productivity of an assembled product: A riskless approach

•A riskless method which does not impose additional costs to producers is introduced.•A series of algorithms for simultaneous selection of optimum tolerances and the best improvement operations are proposed.•Using the algorithms saves large amounts of computer time by pruning many unnecessary evaluations.•It is shown that a certain amount of improvement may maximize productivity and enhance the quality.

In this paper, to show the importance of improvement on savings of costs in a riskless sense, the quality loss and manufacturing cost functions are employed to allocate the components tolerances of an assembled product simultaneous with taking appropriate improvement operations. The use of improvement operations reduces the variability of the process while increasing the production costs. To apply improvement operations in a riskless sense, which actually does not impose additional costs to the producers, we take advantages of the trade-off between improvement costs and tolerance costs. Therefore, a series of algorithms are proposed for simultaneous selection of tolerances and improvement operations so as to minimize the total cost. The use of our approach helps considerably save large amounts of computer time by pruning many unnecessary evaluations. It is shown that proper choices of both improvement operations and tolerances have an important impact to enhance productivity and quality.