Drawbacks of the Classical Procedure

Application of the procedures outlined above guarantees success if followed logically and completely and if design, operating and material parameters are thoroughly under- stood. This is seldom the case in practice. Designs cannot always be evaluated precisely, material properties are seldom specified fully and it is impossible to predict exactly what an operator will do.

In most cases the classical method requires a considerable amount of mechanical-property evaluation possibly materials and process development and a substantial programme of prototype testing, before satisfactory performance can be guaranteed. Sufficient time may not be available to undertake this. The easiest way to reduce the time required is to use the imitative procedure.