Most information for turning graphite applies to milling with inserted cutters. Disposable inserts with a 1/64″ or 1/32″ nose radius are most effectively employed for milling graphite. A positive rake insert is recommended. Cutting fluids and/or coolants are not recommended. Adequate and well-maintained fixturing, rigid tool set-up and well-adjusted machine tools always provide superior results.

When milling large surfaces or volumes, higher speeds and depths of cut can be employed. Use higher strength graphite materials when there are thin walls involved. Depth of cut should always be maximized when possible to eliminate multiple passes. Lower feedrates will allow holding deeper cuts. Feedrates of 0.004/tooth/revolution for roughing and between 0.0005″- 0.002″/tooth/revolution for finishing might be necessary.
Machine setup and measurements are done best with non-contact of the diamond cutting edge. This includes use of a soft material such as plastic or paper for touching off. Cutting edge contact with any hard material prior to cutting may damage the edge.
For multiple-inserted milling cutters it is recommended that axial adjustment be used to align all inserts within q0.0002 for best results. This will improve surface finish and reduce insert wear.
Break out at the end of a pass is always a concern. This can be avoided by having a chamfer cut at the end of the part to ease exit of the tool, or provide stock which can later be cut off.
A wide selection of inserted ball nose inserts is available to accomplish milling profiling in lieu of solid carbide cutters. There are limitations to minimum diameter (0.250″ dia.). Use solid end mill feeds and speeds.
Surface finish improvements can be achieved with tool geometry combined with feedrates. Larger nose radii, including round inserts, will produce improved finish but with increased tool pressure. A smaller nose radius will relieve pressure, but feed must be lessened to achieve comparable surface finish. Depth of cut will not affect surface finish unless it causes excess tool pressure resulting in vibration.