Carbon graphite products can be found in many industries and applications including astronautical engineering, die and mold, aluminum processing, and furnace parts. Graphite is both electrically and thermally conductive, as it has properties of a metal and a semi-metal; and it these qualities that make it ideal in the range of functions that I mentioned. Another ideal quality of graphite is that it is very easy to cut, but it is also quite abrasive and this can cause milling tools to wear rather quickly. The reason for this abrasiveness is the bond strength between carbon molecules. Using diamond coated tools is the best way to cut graphite, as they can last up to 15-20 times longer than uncoated tools. Aside from using diamond cutting tools, there are several ways to ensure that your tools will hold up against graphite’s abrasiveness.
The speed at which the cutting is done is important to consider. Graphite is easily cut at a high speed; and while some say the higher the speed, the longer the life of the tool, this is not necessarily true. It is recommended to keep Vc high, but below 400m/min because if Vc is too high, the diamond film may be subject to wear. It is also important to keep enough feed per tooth. The larger the feed per tooth(fz), the better. If fz is too small, the tool is grinding rather than cutting. Grinding creates significant wear/damage to the tool. Even slightly adjusting fz can greatly improve results.
There is so much that goes into the process of milling graphite; and the speed and feed per tooth are just two factors, but they play a big role in lengthening the life of your tools. So consider the tips above and see what works best for your process.