Using the feed rate formula, calculate the feed rate for RPM 120, cutter with 3 teeth, CL 0.003.

Using the feed rate formula, calculate the feed rate for RPM 120, cutter with 3 teeth, CL 0.003.

• A. 0.108 inches per minute
• B. 1.08 inches per minute
• C. 10.8 inches per minute
• D. 108 inches per minute

Answer: (B)

Feed rate is how far the workpiece moves under the cutter each minute. In milling, each tooth removes a chip equal to the chip load per tooth, so per revolution the cutter removes z × CL inches of material. Multiply that by the spindle speed to get inches per minute: F = RPM × z × CL. Here, z = 3 teeth, CL = 0.003 in/tooth, RPM = 120 rev/min. Compute z × CL = 3 × 0.003 = 0.009 in per revolution. Then 0.009 × 120 = 1.08 in/min. So the feed rate is 1.08 inches per minute. The other options come from decimal placement errors or miscounting the effect of the teeth.

Feed rate is how far the workpiece moves under the cutter each minute. In milling, each tooth removes a chip equal to the chip load per tooth, so per revolution the cutter removes z × CL inches of material. Multiply that by the spindle speed to get inches per minute: F = RPM × z × CL.

Here, z = 3 teeth, CL = 0.003 in/tooth, RPM = 120 rev/min. Compute z × CL = 3 × 0.003 = 0.009 in per revolution. Then 0.009 × 120 = 1.08 in/min.

So the feed rate is 1.08 inches per minute. The other options come from decimal placement errors or miscounting the effect of the teeth.