Engineering Reference

Slotting (full-width cut)

A cut where the cutter engages the full width of the material, leaving the chip nowhere to go.

Definition

Slotting is the hardest common milling operation because the chip has to be evacuated from a closed channel. Recutting an already-cut chip is the main cause of poor finish and rapid wear, and the problem gets worse with more flutes because there is less chip room.

The standard responses are to use fewer flutes, to reduce the feed, or to rough the slot with a smaller cutter and finish it with a full-width pass.

Common misuse

Slotting with a four-flute cutter because it works well for profiling. Profiling gives the chip an open side to escape; slotting does not.

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