Figure 7-81.--Rack milling attachment.
very important because the cutter will be dulled or
Cutter material: You can operate high-speed
steel cutters from 50 to 100 percent faster than
even made useless by overheating. It is almost
carbon steel cutters because the high-speed
impossible to provide any fixed rules that will govern
cutters have better heat-resistant properties.
cutting speeds because of varying conditions from job
Depending on the setup, you can operate
to job. Generally speaking, you should select a
carbide cutters at up to 4 times the speed of
cutting speed that will give the best compromise
high-speed steel cutters.
between maximum production and longest life of the
cutter. In any particular operation, consider the
following factors to determine the proper cutting
Type of cutter teeth: Cutters that have
undercut teeth cut more freely than those that
have a radial face. Therefore, you may run
Hardness of the material being cut: The harder
cutters with undercut teeth at higher speeds.
and tougher the metal being cut, the slower
should be the cutting speed.
Sharpness of the cutter: You can run a sharp
Depth of cut and desired finish: The amount of
cutter at a much higher speed than a dull cutter.
friction heat produced is directly proportional
to the amount of material being removed.
Use of coolant: Sufficient coolant will usually
Therefore, you can often make finishing cuts at
cool the cutter so that it will not overheat even
a speeds 40 to 80 percent higher than that used
at relatively high speeds.