Speeds & feeds
Milling and drilling speeds and feeds: spindle RPM from surface speed and tool diameter, feed rate from chip load and flute count, and material removal rate. Starting values by material and tool type.
Speeds & feeds
Starting points for a general shop: spindle speed from surface speed and tool diameter, feed from chip load and flute count, and how much material comes off per minute.
RPM = SFM · 12 / (π · D) in inches, or RPM = Vc · 1000 / (π · D) with Vc in m/min and D in mm.
Milling: Feed = RPM · flutes · chip load. Drilling: Feed = RPM · feed per rev.
Material removal rate: MRR = feed · axial depth · radial width for milling, feed · π·D²/4 for drilling.
Surface speeds and chip loads are conservative table values. Chip load scales with diameter and drops for harder materials. Drilling runs at about 80% of the milling surface speed. Override either value when you have the tool maker's numbers.
Starting values only. Rigidity, coolant, coating, stickout and radial engagement all move these. Thin radial cuts can take more chip load (chip thinning). Start here, listen to the cut, then adjust. Tool maker data wins.
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