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Can I use more than 2 flutes for shallow ballnose cuts in Aluminum?


I have less than 6 years of experience in CNC and about 2 years with mill programming. I just sort of came into this field working for my Dad. Most of what I have learned about milling has been from CNC Cookbook. I have some parts to program that will require a lot of ball nose milling. I understand why fewer flutes have to be used on aluminum, but it seems like for a lower depth cut like surface contouring with ball nose, with a cutting depth  around maybe .050 to .150, I should be able to use more flutes, say 4 or 5,  so I can run higher feeds. Am I wrong for thinking this way?

  • David Stearman asked 2 years ago
  • last edited 2 years ago
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Best Answer

David, you’re on to something here.  If the chip clearance is good enough for aluminum, you can sneak more flutes in. I tend to do this when 2D profiling with a shallow width of cut.  It’s important to keep a good shot of coolant on it to clear the chips as fast as  you can when you do this.

Will it work when profiling with a ballnose?

That’s a harder case.  The problem is, the ballnose is potentially covered for most of 360 degrees of its circumference unlike the shallow width of cut profiling.  It will take some experimentation to see if it will really work for you, and different profiles will give different results.  I believe the less vertical the final material, the more challenging it will be.

The is another approach though, that will help and is more conservative.  Go to 3 flutes if you’re only using 2.  That’s 50% more feedrate, so not bad.


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