Which unit describes feed rate as movement per spindle revolution?

Which unit describes feed rate as movement per spindle revolution?

• A. Inches per revolution
• B. Millimeters per revolution
• C. Inches per minute
• D. Revolutions per minute

Answer: (A)

Movement per spindle revolution is the amount the tool advances with each turn of the spindle. That makes inches per revolution the unit that directly expresses how far the tool moves for one complete rotation. In metric contexts, millimeters per revolution would do the same job, but the option given in inches per revolution aligns with the idea of per-turn movement most clearly. Keep in mind that inches per minute (or millimeters per minute) describes distance moved per unit time, not per rotation, while revolutions per minute describes spindle speed, not feed. You can convert between per-revolution and per-minute by multiplying the per-revolution distance by the RPM: feed rate (per minute) = (distance per revolution) × (RPM).

Movement per spindle revolution is the amount the tool advances with each turn of the spindle. That makes inches per revolution the unit that directly expresses how far the tool moves for one complete rotation. In metric contexts, millimeters per revolution would do the same job, but the option given in inches per revolution aligns with the idea of per-turn movement most clearly.

Keep in mind that inches per minute (or millimeters per minute) describes distance moved per unit time, not per rotation, while revolutions per minute describes spindle speed, not feed. You can convert between per-revolution and per-minute by multiplying the per-revolution distance by the RPM:

feed rate (per minute) = (distance per revolution) × (RPM).