ABSTRACT

Machining parameters for some thermoplastics are presented in Table 21.9. These values are given in a range and need to be selected suitably depending on the situation (Table 21.10).

The total-time cost per work piece is made up of machine-time cost, nonproductive time cost, and total cost. Machining-time cost is for actual machining and includes overheads and wages. Nonproductive time cost covers setting-up and loading-and unloading time cost. Tool cost combines tool change time cost and actual tool cost. The former is the cost of changing the cutting edge, and the latter is the cost of cutting plus resharpening. When total cost is plotted against cutting speed, an optimum speed for minimum cost is found (Figure 21.2).