8052
« on: December 08, 2009, 03:12:30 AM »
The problem here is heat which is generated by friction.
The low cost bits are made from tool steel (if you are lucky) and will not stand overheating whereas the more expensive carbide bits stand a much better chance of survival.
Cutting bits have side and face clearance which reduces the area in contact with the work and thus quite low friction (heat) is generated but if the cutter flutes become choked with the cuttings then the friction increases at an alarming rate and will ultimately lead to tool failure for all but perhaps the extremely expensive cobalt alloy tools (stellite) which will carry on and just burn their way through.
Using an air jet, aimed at the tip of the tool, will clear these cuttings from the cutter and kerf as well as providing a measure of tool cooling. Shop air, run through a pressure regulator, is just fine for this task.
I have found the single flute carbide cutters to be best for both for wood and plastics as the face and side clearance is much greater than with multi fluted tools. Cuttings don’t get trapped in these tools and so little frictional heating occurs but the low pressure air jet is still desirable. The cutter on the right of this picture is a single flute type and shows the exaggerated side and face clearance quite well.
Tweakie.
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