Function Costing: A Potential Aid to Designers

A potential aid to engineering designers is offered by the concept of function costing. Many functions can be quantified and the cost associated with that function is often simply related to the quantity or quantities. Obtaining reliable data is difficult, except in the case of components marketed as such, but fortunately there are many of these, such as bearings, reduction gearing and actuators. The problems of modelling cost in terms of function are briefly addressed. The uses of function costing are also discussed, the estimation of cost directly from the specification, the comparison of alternatives, and the detection of areas of potential cost reduction, as in value engineering. An important principle is that the costs used for modelling should be representative of the best (i.e. most economical) practice, wherever found.