When machining graphite electrodes compared to copper electrodes, the cutting resistance is lower, and the coefficient of thermal expansion and contraction is smaller. Consequently, it is generally easier to machine thin-walled structures. However, machining graphite electrodes comes with its specific challenges and problems, with the most common being edge chipping. Experienced engineers have summarized the following guidelines based on their expertise to minimize the occurrence of edge chipping during the graphite machining process:
1. Pre-mill a small section at the exit end of the workpiece to prevent edge chipping when cutting near the exit.
2. Employ climb milling, meaning the cutting edge moves in the opposite direction of the feed direction.
3. Do not exceed a cutting depth greater than one-third of the milling cutter diameter.
4. Set the dust collector air velocity as follows: Processing area > 150 meters per minute; Dust exhaust > 600 meters per minute.
5. Replace worn-out cutting tools in time.
6. Increase cutting tool linear velocity and reduce feed rate.
7. Use high-quality fine-grain graphite materials whenever possible.
An especially important recommendation is to use CVD diamond-coated end mills, as they have a lower overall friction coefficient and are ground to precise geometric dimensions, making them ideal for preventing edge chipping in graphite workpieces and machining thin-walled graphite components.