Feeds & Speeds Reference

Starting-point cutting speeds for HSS tooling by material, plus the RPM formula for turning and milling. Use as a guide — verify against your tooling manufacturer's data for production work.

HSS Cutting Speed Reference

Material	Turning (m/min)	Turning (ft/min)	Milling (m/min)	Milling (ft/min)
Mild steel	25–35	80–115	20–30	65–100
Medium carbon steel	18–27	60–90	15–24	50–80
High carbon steel	12–18	40–60	10–15	33–50
304 Stainless steel	20–30	65–100	15–25	50–80
Cast iron (grey)	20–30	65–100	15–25	50–80
Aluminium	75–150	250–500	60–120	200–400
Brass (free-machining)	60–100	200–330	50–90	165–300
Copper	40–60	130–200	30–50	100–165
Nylon / plastics	50–100	165–330	40–80	130–265
Titanium alloy	8–15	26–50	6–12	20–40

RPM Formula

Metric: RPM = (Cutting Speed × 1000) ÷ (π × Diameter)

Where cutting speed is in m/min and diameter is in mm.

Imperial: RPM = (Cutting Speed × 12) ÷ (π × Diameter)

Where cutting speed is in ft/min and diameter is in inches.

Quick estimate: RPM ≈ (1000 × Vc) ÷ (3.14 × D)

Start at the lower end of the speed range for tough materials, worn tooling, heavy cuts, or poor rigidity.

How to Use This Reference

These values are starting-point recommendations for HSS (high speed steel) tooling. Carbide tooling runs significantly faster — typically 3–5× the HSS cutting speed for the same material. Actual speeds depend on tool condition, machine rigidity, depth of cut, coolant availability, and workpiece material variability.

Start conservatively and adjust based on chip colour, surface finish, and tool wear. Blue or discoloured chips on steel indicate excessive heat — reduce speed or increase coolant. These figures are a guide only — verify against tooling manufacturer data for critical production work.

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