Cutting Speed, RPM and Feed

Core relationships

• Spindle speed: n = (Vc × 1000) / (π × D)
• Table feed: vf = fz × z × n
• ap is axial depth of cut; ae is radial width of cut.

Why a calculated value is not automatically a recommendation

The formula only expresses a mathematical relationship. The workpiece material and hardness, tool geometry and coating, tool overhang, machine rigidity, operation type, cooling and chip evacuation all affect a safe starting point.

Warning signs

• Rubbing or polished marks may indicate insufficient chip formation.
• Irregular noise and vibration require checks of overhang, clamping and runout.
• Built-up edge, rapid flank wear or chipping require the whole cutting system to be reviewed.