Design for serviceability

摘要

A design team working on a complex industrial machine found it could shave manufacturing costs by eliminating several pull-up resistors in sensor circuits. Unfortunately, a sensor failure in the field caused the circuit to "float" and make the equipment behave unpredictably. The small up-front savings were more than offset by manifold increases in downtime and maintenance costs. This example underscores a truism of engineering design: Decisions made early in product development strongly influence life-cycle costs. Studies show that conceptual design accounts for only 4% of product cost and results in 70% of the total life-cycle costs. In the entire product-development phase, conceptual design accounts for 15% of initial product cost (including manufacturing equipment and production tools) and results in 95% of the total life-cycle costs. Other studies suggest that an additional 5% invested in improving part design can lower lifetime maintenance costs by 25%.