Before the preliminary design has progressed further it should be subjected to a critical review by all those who are connected with the product such as quality engineers production engineers and sales personnel. The design engineer could explain the salient features of the design with the help of mockup model. During this review each functional representative should be allowed to comment on the design from his point of view. The quality engineer for instance could highlight the quality problems which were faced in the similar previous product during manufacture. This could be in the nature of difficulty of testing a particular quality parameter or the tolerances of a component which affected the performance or the unreliability of a particular mechanism. He could also suggest the methods by which such a problems could be avoided in the present product.