In FR = RPM × T × CL, what unit is the feed rate expressed in?

In FR = RPM × T × CL, what unit is the feed rate expressed in?

• A. Inches per minute
• B. Seconds per minute
• C. Degrees per minute
• D. Meters per minute

Answer: (A)

Feed rate is a linear speed—the distance the tool advances per minute. In this formula, RPM is revolutions per minute, T is the number of teeth (a count, dimensionless), and CL is the chip load per tooth expressed in inches per tooth. Multiply RPM by the number of teeth to get how many teeth engage per minute, then multiply by the chip load per tooth to convert that into a length moved each minute. The result is inches per minute. If you used millimeters per tooth for CL, you’d get millimeters per minute instead. The other options don’t represent a distance moved per time, so they don’t fit the context.

Feed rate is a linear speed—the distance the tool advances per minute. In this formula, RPM is revolutions per minute, T is the number of teeth (a count, dimensionless), and CL is the chip load per tooth expressed in inches per tooth. Multiply RPM by the number of teeth to get how many teeth engage per minute, then multiply by the chip load per tooth to convert that into a length moved each minute. The result is inches per minute. If you used millimeters per tooth for CL, you’d get millimeters per minute instead. The other options don’t represent a distance moved per time, so they don’t fit the context.