TABLE OF CONTENTS Selecting a process follows a strategy much like that for materials: translation of requirements, screening of the options, ranking of the processes that survive screening, ending with a search of documentation for the most promising candidates. For processes, translation is straightforward-the requirements convert directly into the attributes of the process to be used in the screening step. Process attributes capture their technical capabilities and aspects of product quality. All process families require screening for compatibility with material to which they are to be applied, but after this the attributes and constraints are specific to the family. For shaping, component geometry, precision and finish are most discriminating. For joining it is joint shape and mode of loading. For surface treatments it is the purpose for which the treatment is applied (wear, corrosion, aesthetics, etc.). Ranking is based on cost if this can be modeled, as it can for batch processes. Cost models combine characteristic process attributes such as tooling and capital costs and the production rate, with user-specified parameters such as overhead rates and required batch size. The economic batch size provides a crude alternative to the cost model a preliminary indication of the batch size for which the process is commonly found to be economic.
Translation of the design requirements frequently points to important aspects of processing that fall beyond a simple screening process. The avoidance of defects, achieving the required modification of material properties, and determining the process speed (and thus economics),...
