There are a variety of CNC milling cutters used for different projects. The most common of these are endmills. They vary in size, geometry, coating, and material.
Although endmills are made of many materials, they are typically carbide or high speed steel (HSS). The type of material being cut and the machine’s maximum spindle speed determine which should be used.
Here are the different types of endmills:
Flutes- These have a spiral cutting edge
- 2-Flute: allows maximum space for chip ejection; used for general milling operations
- 3-Flute: great for slotting; used in general milling operations
- 4, 5, 6, and 8-Flute: a larger number of flutes reduces chip load and can improve surface finish
The most commonly used are 2, 3, or 4- flute. It’s suggested that when cutting aluminum, one shouldn’t use more than 3 flutes. However, when cutting other material, generally 4 flutes is the most common.
Ball End- Used to mill die cavities and fillets, round bottom holes and slots.
Corner Radius- This is a conventional endmill with radius ground on the tips of the flutes. This helps reduce chipping on the tip.
Left-Hand Spiral- This endmill is used for milling multiple layers of thin sheets where chip flow is directed away from the work.
Rougher- This endmill has an interrupted shape on the outside diameter to remove large amounts of material quickly. The serrations in the teeth break up chips and are less prone to chatter.
Stub Length- this one is used for milling shallow slots in materials where heavy feeds are required and tool deflection is minimized.
Endmills can be purchased as single or doubled ended. Double ended mills have teeth on both sides and generally cost less than purchasing two single-ended counterparts. However, endmill holders need sufficient clearance to allow for a doubled-ended mill.