TABLE OF CONTENTS 
The last chapter described a systematic procedure for process selection. The inputs are design requirements; the output is a ranked short-list of processes capable of meeting them. The case studies of this chapter illustrate the method. The first four make use of hard-copy charts; the last two show how computer-based selection works.
The case studies follow a standard pattern. First, we list the design requirements: material, shape, size, minimum section, precision, and finish. Then we plot these requirements onto the process charts, identifying search areas. The processes that overlap the search areas are capable of making the component to its design specification: they are the candidates. If no one process meets all the design requirements, then processes have to be "stacked": casting followed by machining (to meet the tolerance specification on one surface, for instance); or powder methods followed by grinding. Computer-based methods allow the potential candidates to be ranked, using economic criteria. More details for the most promising are then sought, starting with the data sources described in Chapter 15. The final choice evolves from this subset, taking into account local factors, often specific to a particular company, geographical area, or country.
Fans for vacuum cleaners (Figure 8.1) are designed to be cheap, quiet, and efficient, probably in that order. The key to minimizing process costs is to form the fan to its final shape in a single operation that is, to achieve net-shape forming leaving only the central hub to be...
