Cutting Tools for CAM, Part 8 (Conclusion)
Why so many end mill flutes? New cutting tools for dynamic machining processes.
Cutting tool vendors have taken notice of cutting motions like those incorporated in Mastercam’s Dynamic Motion Technology to reduce tool wear and increase machining efficiency. They are now introducing tools designed specifically to take best advantage of this technology.
ISCAR, for example, has introduced some new chatter-free carbide end mill designs for heat resistant alloys. They allow toolpaths incorporating dynamic motion to operate at higher cutting speeds (up to 800 ipm) and provide better surface finishes. The new 1/2-inch endmills have 10 and 12 flutes. The new 3/4-inch end mill has 20 flutes.
Why so many flutes? The flutes of end mills are continuously engaging and disengaging as they rotate against the material. The more flutes there are in the tool, the higher the table feed will be. This equates to a higher metal removal rate, which reduces the cycle time. Having more flutes in the tool also increases tool life because each flute will be removing less material per part than a tool with a smaller number of flutes.
Special coatings on the cutting protect it and optimize its performance at high temperatures. Maintaining consistently high temperatures is best for optimal cutting performance and tool life. That is why it is best to cut steel and some stainless alloys without coolant.
However, if the workpiece is made of a material that is heat resistant (so that it carries very little heat away from the chip), then coolant is required. However, coolant that works its way directly into the cut will cause thermal cycling that will compromise the tool’s coating and shorten tool life.
The new tools with more flutes represent just one example of how cutting tool vendors are looking for ways to provide greater synergy between advanced cutting approaches like Dynamic Motion Technology and their tool designs.