Machinery's Handbook - 4: Cutting Speeds and Feeds
|WARNING: Machine tools present a safety hazard. Improper operation can result in severe injury. These topics are for non-laboratory study only and are not to be used in conjunction with the operation of any tool or machine described herein. Never use a machine tool without the supervision of a qualified instructor.|
|Now the machining must begin.
What RPM should be used for a 3" diameter work piece?
What should be the feed rate?
A table in the Machinery's handbook gives RPM and Feed rate for 4130 steel with 380 BHN: Feed rate is shown to be .028 inches per revolution and speed is 240 feet per minute.
Note: Cutting Speed in surface speed per minute is often simply abbreviated as CS. So the CS of this metal* is 240.
To find the correct RPM the following formula can be applied:
RPM = (CSx4)/Dia. or (240 x 4)/3 = 320
Feed rate in inches per minute (instead of inches per revolution) can be found with this formula:
Feed=RPM x IPR where IPR is inches per revolution
Feed = 320 x .028 - 8.96 inches per minute.