Milling Cutters and Cutting Fluids - 2: Endmill Geometry
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|End mills are cutters that have an end-cutting capability. They machine on the end as well as the sides. There are two types of helixes used on end mills: right end and left end. You must be thinking about chip removal to decide which one you want to use. A convention is usually that the cutter is right end if it rotates counterclockwise when viewed from the cutting end.
There are end mills with two flutes (left) and end mills with more than two flutes. (right)
The multi-flute end mill will produce a better finish than the two flute end mill at the same RPM and feed but it will have less chip clearance space and therefore will be less convenient in a heavy cut of soft material. Multi-flute end mills are typically more expensive.
There are end mills that are center cutting (like those above) and end mills that are not center cutting (right). In the case of the non-center cutting end mill, you can not plunge into the material and will have to start your cut on the outside of the part. Non-center cutting end mills are more difficult to fabricate and are therefore more expensive, however they do lend themselves to hollow centers that can distribute coolant.