To obtain minimum burr tube ends it is essential that heat buildup be avoided. When either tube or the tool bit gets hot, the tube material starts to flow or push away from the tool edge as a burr, instead of being cut cleanly with a minimum burr.
The three basic operating conditions which generate excessive heat along with corrective actions are:
- Excessive cutting speed. Keep the RPM’s low.
- Excessive depth of cut. Keep the chip curling loose.
- Dull tool bits. Speed and cut depth accelerate tool bit wear which compounds the problem.
Cutting speed (RPM) is actually a range depending on the material conditions. Some judgments, based on the cut conditions must be made to select the actual speed. Generally the cutting speeds should be:
Time / Head Revolution
|1/4″ (6.35mm)||30 to 60||1 to 2 seconds|
|1/2″ ( 12.77mm)||20 to 40||1.4 to 3 seconds|
|3/4″ ( 19.1 mm)||15 to 30||2 to 4 seconds|
|1″ (25.4 mm)||14 to 25||2.4 to 4 seconds|
|2″ ( 50.8 mm)||10 to 15||4 to 6 seconds|
4″ (101.7 mm)
5 to 10
6 to 12 seconds