To obtain optimal tube ends with minimum burr it is essential that heat buildup be avoided. When either the tube or the tool bit gets hot, the tube material starts to erratically flow or push away from the tool edge as a burr instead of being cut cleanly.
The three basic operating conditions which generate excessive heat and cause you to take corrective actions are:
1 Excessive cutting speed. (Keep the RPMs appropriate.)
2 Excessive depth of cut. (Keep the chip curling freely.)
3 Dull tool bits. (Always use sharp bits for best cutting.) (Note: Excessive speed and cut depth accelerate bit wear.)
The best cutting speed (RPM) is actually a range depending on many variable conditions. The operator should be able to determine the ideal speed based on real cutting results. Generally speaking, the recommended cutting speeds are: