6.3 Looking ahead
All these choices represent a best attempt to provide adequate performance by the gears at minimum cost. 'Adequate' means providing trouble-free service for a given design life. Notice that when the material is changed (for example, from nylon to iron), then so too does the preferred manufacturing process. Clearly it is the properties of a material (such as its strength) which decide whether the product will have adequate performance, and it is also the properties (such as the way the material melts) which decide how the product can be made.
This interdependence between properties, the product, the process and the price is complex. However, you should now be aware that there is a vast array of processes available to the manufacturer for the production of a particular component, and you should know a bit more about materials' properties, so that you can begin to understand the reasoning behind adopting a particular processing route.