Machining Aluminum

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Wayne74

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I have a Brigdeport Model J series 1, I am machining aluminum to a depth of 1.375" with a .375 2 flute end mill specifically for aluminum running at 1100 rpm with flood coolant ( soluble oil & water. How deep can I cut in one pass?

Thank you.
Wayne
 
It should cut fine at .375 DOC, maybe even .500, try it and see how it feels. You may have to adjust your feed & speed a bit.
 
The 10% refers to a percentage of the diameter of the cutter. So in this case about 0.037. If you are cutting the outside profile or an internal pocket, you would move over 0.037 for each pass at 10%. If you are cutting an on size slot, there would be no stepover and you would be at 100% of the cutter diameter.

I'm not in total agreement with vertcnc in going full depth on the roughing passes, but there is nothing wrong with doing it that way. I normally reserve that for the final finish pass at about 0.010 stepover, and 0.010 DOC. I normally make my roughing passes at cutter diameter or maybe 150% cutter diameter on the DOC, with a 40% stepover. The exception to this is with roughing end mill, then I normally go up to full cutter depth at a reduced feed rate, and a 90 -100% stepover.

There is really no wrong way to do it, it's a matter of what works best for you and your machine.
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I was just doing this, cutting aluminum with a 5/16 four flute cutter. Any deeper than .150 gave me more chatter than I like. (Running abut 800 in my PM25).
 
Taking that depth in aluminum will produce LOTS of chips quickly. I would suggest using compressed air set at about 40 psi and blow those chips out as it is cutting. Do put up guarding to keep the chips from going all over the place. Spray mist set at a high pressure works too! Not much on water flood coolant on a mill unless it is CNC with full guarding.

Something else I suggest, use a shorter length end mill to get the slot started. Then go in with the longer end mill to get it to the depth needed.
 
Lot's of ways to skin this cat. Multiple step downs with a final finish pass of .015 or so at full depth will also work fine. Bridgeport should be plenty rigid.
Check out this feed and speed calculator, it will give you a pretty good idea whats possible.

http://zero-divide.net/index.php?page=fswizard

Tom: The problem with the smaller machines is rigidity. I would use a 2 flute HSS end mill, 4 flute will load-up pretty quick. and the PM25 doesn't really have enough HP to utilize it. I regularly use the Hertal brand 2 flute form Enco and have really good luck. On the smaller end mills (1/4" or less) carbide is quite a bit stiffer. Here again, I would have the RPM's maxed out. Shortest end mill possible for the cut. Need more cut details to make a more educated diagnosis. Is the cut, a slot or contour cut? Width of cut? What alloy? 6061 or 7075 is good, 2024 can be a little tricky (gummy).
 
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