In defining high-speed machining, the real question that must be asked is this: "How much of the available speed, and power can be used at the cutting edge or cutter work- piece interface?" This is not necessarily easy to determine. The phenomena in high- speed machining are different than those of conventional machining, and sometimes they are even counter-intuitive. Four key actions to a better understanding of machine dynamics are: testing the equipment oneself, having outside testing done, maintaining and using a results database, and creating and implementing repeatable setups.

The importance of understanding machine dynamics becomes evident in high-speed machining, then, when we consider their affect on such issues as specialization in machines, matching tools to machines and optimizing machine usage. Titanium machining, for instance, occurs mostly in the lower-speed process damping range. For this reason, a lower-speed, higher-torque spindle is preferable. Aluminum machining, on the other hand, occurs primarily in a much higher speed range. Therefore, a high spindle speed is preferable.

The second consideration is tool tuning, that is, the process of matching tools to machines. This is only possible once the machine user has derived a database of performance information from experiments with the machine. For each tool, the user should be able to deduce a preferable speed and a maximum depth of cut. In examining the data, it will become evident that some lengths are preferable to others and demonstrate a higher metal removing rate.

The third consideration is the optimization of machine usage. In terms of spindle speed, tool tuning often reveals that it is necessary to use tools at speeds significantly lower than the maximum achievable speed. Moreover, many tools prefer speeds lower than the maximum spindle speed. These findings indicate that it would be preferable to design a spindle with a specific tool in mind, then place the stable zone.

Clearly, it is evident that there are many benefits to be realized by the proper understanding and utilization of machine dynamics. The most important step in getting there, however, is to understand your machine. Know what it can do, and how it best performs. This knowledge can only be gleaned by testing, retesting and more testing. Tool tuning is a valuable resource for maximizing machine potential. Keep accurate databases of your findings, and strive for repeatability in each test. If you follow this advice, successful optimization with high-speed machining techniques will be well within your reach.

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