Identified content errors were corrected on 2026-10-25. Sources and scope for this page: Sandvik Coromant — machining formulas and definitions (accessed 2026-10-25), covering turning speed and feed arithmetic. The geometric roughness estimate has the limited assumptions stated above; it is not a universal troubleshooting rule. What the 2026-10-25 correction changed is stated with the source above; nothing beyond that scope was re-checked. How sources, methods and updates are recorded.
Last updated 2026-10-25
Different quantities, connected choices
Surface speed is the relative cutting-edge speed, usually m/min or ft/min. Feed is advance per revolution, per tooth or per minute. For turning at diameter 50 mm and 1000 RPM, vc = π × 50 × 1000 / 1000 = 157.08 m/min. At f = 0.2 mm/rev, linear feed is 200 mm/min.
Diagnose poor finish before changing a setting
Surface finish can be affected by feed marks, edge geometry, built-up edge, tool wear, runout, deflection and vibration. Depending on the cause, a change in cutting speed can improve or worsen the result. Check the relevant manufacturer troubleshooting guidance.
Ra ≈ f²/(32r) is an idealised turning geometry estimate for a conventional rounded nose, with consistent length units and small feed relative to radius. It excludes wipers, wear, vibration and material effects and is not a measured-finish guarantee.
Basis and scope
Sandvik Coromant — machining formulas and definitions: Turning speed and feed arithmetic. The geometric roughness estimate has the limited assumptions stated above; it is not a universal troubleshooting rule.