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Slot Cut in 1/4” Aluminum

793 Views 10 Replies 5 Participants Last post by  Shop Dog
Hello,

I am trying to cut parts out of 1/4” aluminum plate with a 3hp water cooled spindle. I am using a 2 flute up cut carbide end mill with mist coolant and have gone through about 10 bits so far.

I have tried various feeds and speeds, and although each have worked to some degree, the cutter gets clogged and it’s game over in the middle of the part.

I would appreciate any suggestions/cutter style and recipe that have rendered good results.

Thanks, Steve
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hey Dog - photos of your project and issues may help with the most accurate replies.
Are you using O-flute bits? For example those sold by Amana dealers such as Solid Carbide CNC Spiral 'O' Flute, Aluminum Cutting ZrN Coated Up-Cut Router Bits
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No, not using 0 flute. Using 2 flute as I mentioned above. I have ordered a couple of 1 flute to see how that goes.
No, not using 0 flute. Using 2 flute as I mentioned above. I have ordered a couple of 1 flute to see how that goes.
The terminology is letter O, not number 0, flutes to describe router bits the geometry of the flutes designed for use with aluminum or plastics, and has nothing to do with the number of flutes. I suspect that if you used O flute bits you would not have the problem you described.
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Thanks for the clarification with the O vs 0. I have attached a few photos. The machine, trashed cutters and the part that I am making. I am cutting the overall part out of a 1/4" aluminum sheet. Since it is CNC and easy to go back and run from a particular line of code, I have made this piece, but it took 3 end mills to accomplish the cut out. I am going to try to use the G-WIzard recipe, although it seems crazy fast and deep. More to come...

Thanks,

Steve

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Looking at all that molten aluminum, it would seem that you are spinning too fast, or feeding too slow, or a combination of the two. As others have said, you are not using the best bit for aluminum, either.
Thanks for the note. Actually, I took a deeper cut .125 with the same speed and feed and successfully made a couple of parts. The speed was 16,000 and the feed was 12ipm.
Looking at all that molten aluminum, it would seem that you are spinning too fast, or feeding too slow, or a combination of the two. As others have said, you are not using the best bit for aluminum, either.
Looking forward to seeing some of your successful projects !!
Thanks for the note. Actually, I took a deeper cut .125 with the same speed and feed and successfully made a couple of parts. The speed was 16,000 and the feed was 12ipm.
That is way too slow a feed rate - you are overheating the bit. Not at all surprising you went through a lot of bits. If you are using 1/4" end mills, your F&S (12 IPM and 16000 RPM) yields a chip load of 0.0004", A quick survey of 2 flute amana 1/4" bits shows they recommend a chip load range of 0.004" to 0.006" for aluminum - at least 10 times larger. To get that with 16000 RPM, you would need a feed rate between 128 and 192 IPM. If you are using a 1/8" end mill, your feed rate needs to be 80 IPM.

This might help you understand chip load and how it relates to F&S a little better.
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Thank you very much for the information and the chip load link. Very helpful. I have been playing around with GWizard software which has been interesting. When considering a slot over one open side, it changes significantly in their formulas. There is a slow and fast setting (finish quality) and with all other things being equal, the IPM at .01 chip load, the rate varies from 35 to 146.

That is way too slow a feed rate - you are overheating the bit. Not at all surprising you went through a lot of bits. If you are using 1/4" end mills, your F&S (12 IPM and 16000 RPM) yields a chip load of 0.0004", A quick survey of 2 flute amana 1/4" bits shows they recommend a chip load range of 0.004" to 0.006" for aluminum - at least 10 times larger. To get that with 16000 RPM, you would need a feed rate between 128 and 192 IPM. If you are using a 1/8" end mill, your feed rate needs to be 80 IPM.

This might help you understand chip load and how it relates to F&S a little better.
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