Increased Productivity by Special Techniques
The inability to improve cutting-tool performance by developing new cutting-tool materials—coatings in particular—has been very frustrating. Likewise, very little improvement in productivity has been experienced by exploring new combinations of speeds, feeds, and depths. However, developments of interest include specially designed turning tools and milling cuttings along with the use of a special end mill pocketing technique.
In recent years, ceramic tools have been used successfully in machining high-temperature alloy jet-engine components at speeds much higher than those conventionally used. At speeds of 183 to 213 m/min (600 to 700 ft/min), tool life is short (3 to 5 min), but it is possible to finish a cut at these speeds and then index the cutting tip for making the next pass. This same technique has potential in machining of titanium with C-2 carbides. Data are needed to determine the speeds at which reproducible and reliable tool life of the order of 3 to 5 min can be obtained, and to determine whether these conditions improve the economics of titanium machining.
One of the practical techniques for increasing productivity is to determine the optimum cost in machining a given titanium part for a specific machining operation. If specific data are available relating tool life to speed, feed, and depth for a given operation and cutter, it is possible to calculate the overall cost and time of machining as a function of the cutting parameters. Some companies are now using computers to perform such cost analyses and to arrive at minimum costs and optimum production rates for specific machining operations.