TABLE OF CONTENTS Here we have examples of the selection methodology in use. In each case, translation of the design requirements leads to a target list of process attributes for screening. Three shaping problems are approached using the charts of this chapter, with the cost model applied to the last of the three. These are followed by examples of selecting joining and surface treatment processes. For these we use the CES software; the charts show only the broad classes of joining and finishing processes, whereas the level of detail in the software is much greater. In each case, aspects of processing beyond the scope of simple screening are noted. These relate to defects, or material properties, or economic limitations all of which can be addressed by seeking documentation.
The anatomy of a spark plug is shown schematically in Figure 18.21. It is an assembly of components, one of which is the insulator. This is to be made of a ceramic, alumina, in an axisymmetric, hollow 3-D shape. The insulator is part of an assembly, fixing its dimensions. Given the material and dimensions, the expected mass can be estimated and the minimum section thickness identified. The insulator must seal within its casing, setting limits on precision and surface finish. Spark plugs are made in large numbers the projected batch size is 100 000. Table 18.5 lists the constraints. The lower part of the table flags up key process-sensitive outcomes which cannot be checked by screening, but should...
