What is the difference between a 2 flute and 4 flute end mill?
Small and closed space is more suitable. Therefore, the keyway cutter for milling keyway is 2 fluted. In addition, the more flutes, the more feed. So there's even a six flute end mill for finish machining. The 3 flute end mill is mostly used for milling aluminum. The chip removal space is large and it is not easy to stick the cutter.