Six-sigma design [quality control]

The approach to customer satisfaction taken at Motorola is described. It is based on two conclusions derived from various studies: A product is built in the shortest time and at the lowest cost if no mistake is made in the process; and if no defect can be found anywhere in the process of building a product for the customer, then the customer probably will not find one either. Beginning in 1987, Motorola designers were required to adopt ±6-sigma tolerance limits, i.e., product design margins were to be twice the normal variation of the process. The way in which this was implemented in a six-step design process is described