The successful and most cost-effective design of a given component is dependent on many factors. The same is true for the selection of the material for a particular application. One must consider a host of material, design, manufacturing and application factors. The material is not first selected and the application made to fit that choice. Rather, various factors (Table 1) must be considered and the material selected to meet those needs.
The requirements for manufacturability, performance, cost and fitness for purpose must all be considered. The engineering requirements for each end-product must be known. Quality engineering within and between all engineering and business disciplines – manufacturing, tooling, mechanical, metallurgical, logistics and economic – must be integrated. The result will be a properly engineered and cost-effective product.
In conducting a design/material analysis, the basic questions to first answer are:
1. What must the component endure during service (i.e. product requirements)?
What are the rigors of the application, and what is the design life? Must it provide premier service, or is there an adequate design life that is involved (i.e. other factors will end its service long before its useful life is expended)? What loading, lubricants, temperature and contaminants are involved? Other service/performance aspects specific to a particular product must also be factored into the selection process.
2. How is the component to be made (i.e. process requirements)?
How will its basic form be generated, and how will it be heat treated (if at all)? Will you try to introduce particular mechanical properties and, if so, how – by heat treatment or mechanical means? Is geometry or surface finish important, will special coatings be used, is dimensional control (stability or stability at temperature) an issue? Other processing aspects specific to a particular product must also be considered.
Obviously, process development and product development are not separate entities. They are highly interdependent, and both must be considered. One must also recognize, however, that today's cost demands often require some compromises in material selection to meet logistical, supply-chain and inventory requirements. Fortunately, that does not mean that material selection needs to be minimized. If done correctly, the needs of all parties can usually be met with excellent success while maintaining realistic economic, manufacturing and performance goals.