surface fin in aluminum

[Jeremy Grigsby]

I'm going to be machining a 30 inch rad as a profile on the face of a part. It is a convex rad about 4 inches long. I need to get it done as quickly as possible while maintaining a 125 or better surface finish. There is also a .500 radius between the large radius and a flat. The ball mill would have to profile this too. Any suggestions on type of tool best suited, no of flutes, feedrate, stepover etc. Any help would be appreciated. Thanks.

[strabe]

2 flute carbide 3/4" ball mill, max rpm. Try flowline toolpath with no more than .005 stepover. That should keep you under a 125 finish.

 

HTH

 

Ken

[jeff]

2 or 3 flute 3/4 ballnose will be fine.

Not too sure about max rpm, unless your machine only goes to 6,000 lol.

.005 stepover, and about .002 ipt

try that as a starting point, you may find yourself going faster on the feedrate

[MLS]

What they said or you could go with a 1" ball and up the stepover a bit then be able to profile the .50" radius instead of keller it in.

 

I would stick with a 2 flute carbide cutter especially if the tip will be doing a lot of work.

 

If it is 6000 series or up T condition aluminum you can run the RPM up to 15K probably, but if is softer like 2024 you might have to run the RPM slower to avoid slagging.

[Matthew Hajicek - Singularity]

If you use a bull endmill it will act like a much larger ball does, but will fit in the .5 radius, as long as I'm imagining your part correctly. A ball, when cutting a shallow slope, is cutting with the tip at a very small radius, almost dragging the tip instead of taking a slice through the stock. You could use a 3/4" or even larger bull (even a multiple-inch insert cutter) with any sort of corner radius, so long as you know what that radius is. It will swing the cutting edge through the work instead of dragging it, plus on such a shallow dome it will act like a 6" or something ball mill as far as scallop height goes.

 

One caveat, this only works when you're cutting up and down the hill, not along it. For a dome you'll want a radial toolpath; perhaps one going from the center to halfway out, and another as a doughnut around the first at a finer angular pitch.

[Jeremy Grigsby]

Thanks for all the suggestions. I already ordered a 3/4 2 flute 45 degree helix ball. Anyone know what the cusp height would be for a 125 fin?

[Gary]

I would run .0002 scallop height to start/.