RobbJack: How to Select an End Mill

Select the shortest flute length possible for the application. Shorter flute length end mills offer better stability and increased feed rates.

Select the largest diameter possible for the application. Increasing diameter by 10% provides 25% more strength.

Number of Flutes Selection Chart

Rough Slotting/Pocketing

Two and three flute end mills can be used in non-ferrous and ferrous materials with depth of cuts not exceeding one diameter per pass.

Three and four flute carbide Ruffers can be used for rough pocketing and profiling operations in many ferrous materials with radial depths of cuts not exceeding 25% of the diameter.

Finish Slotting/Peripheral/Pocketing

Three, four and six flute end mills offer greater stability with increased feed rates for finishing.

RobbJack recommends Climb Milling (as opposed to Conventional Milling) for most applications (assuming back-lash control in the machine). Climb Milling generally allows better flute engagement in the material, resulting in more efficient machining and superior part finishes. Conventional Milling can lead to work hardening in some ferrous materials

Click here for Speed and Feed Calculation Formulas