Tolerancing subjective and uncertain customer requirements regarding perceived product quality

Abstract

Defining “quality” from customers’ perspective and controlling it throughout the product development process is a fuzzy and enduring task, especially for companies that are, simultaneously, fighting cost pressure and shortening product and technology life cycles. The poor predictability of customer demands complicates the definition of established requirements. During the product development process, product experts interpret the customer requirements and transfer them into product specifications. Due to the subjective nature of customer demands and the vast field of human perception, a huge number of product parameters have to be analyzed and specified to assure a comprehensive and successful approach. In order to keep an adequate cost–value ratio in production, it is not possible to pinpoint “hard” tolerances for each parameter. This article depicts the structured approach to choose the parameters, which are relevant for the customers’ quality judgment, and to tolerance “soft” customer perceptions. The emphasis lies on defining and scaling product parameters by combining product tests, interviews and focus groups for evaluation and interpretation by statistical means. Furthermore, the gathered information will be transferred into a “describing” specification, which will be supported by a tolerancing process based on statistical means.