Newbie Advice re Milling Aluminium

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Thread: Advice re Milling Aluminium

  1. #1
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    Default Advice re Milling Aluminium

    Hi All,

    I have a 6040 CNC machine with an 800W watercooled brushless motor. Using Artcam Express 2013, Mach3 and a UC100 motion controller. With this setup, I can quite happily design and mill 2D shapes, usually in MDF. I have the 6040 housed inside a perspex & MDF enclosure with a dust extractor nozzle close to the workpiece, connected to my vacuum cleaner.

    I need now to be able to mill 2D and 3D shapes in aluminium. I have the G-Code and have milled two test pieces out of MDF and an old offcut of kitchen worksurface. The 2D shapes will be milled out of 6mm aluminium plate and the 3D shapes, out of 40mm aluminium block. I purchased two good quality end mills, one is a 6mm 2 flute, the other a 3mm 2 flute. I have used the various calculators to determine the correct spindle speed and feed rate. They all give fairly comparable results so I guess they must be correct. However, when I set the 6040 going, she seems to be rushing too fast and the surface finish is poor.

    I have watch many YouTube videos of people happily milling 3D shapes where the 6040 seems quite happy. My first attempt is shown in the attached photo. I did use a cutting oil sprayed onto the end mill from an aerosol can. To what should I set the spindle speed, feed rate, step down, etc, to correctly mill this 3D block? Is slot milling a sensible idea?

    Any help gratefully received.

    Regards

    Gary

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    Default Re: Advice re Milling Aluminium

    Well, your passes may be too deep for starters. Especially when slotting like you're doing, you have full tool engagement, so take less depth per pass. Also if you cut wood, especially particle board, with your endmill, you wouldn't want to use on aluminum after. Another thing - don't know how you're holding the work down, but it has to be rock solid. With that part I would have drilled the holes first, then you can bolt or screw the work down, before doing the profile passes. I'd probably drill two holes before milling the slug out, because once that gets free, it can shift and jam or break your endmill.



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    Default Re: Advice re Milling Aluminium

    Ok here is what i see going on, I agree with louieatienza on many points. First you want to use the same bit for cutting Aluminum only... I see some slight engraving the bit did between traveling to start points. You need to set you Z travel height higher. You should clear your material by at least .250" when cutting. The other thing i see is how did you hold your material to the table. You have one of 2 issues here or both. If your material moved while cutting it was not held down properly. The material should NEVER move.... Or if your material didn't move then your machine lost registration during the cut. So basicly you were cutting to deep and too fast for the motors to keep up and they skipped. Could be from using to big a diameter a bit as well. Either way you need to cut maybe 1/16" per pass at a slower feed rate to not apply so much back pressure on the bit/machine. I cant tell from the image but i would also recommend some sort of cutting fluid to keep the bit cool and less friction on the cutting surface of the bit. You could spray a little WD-40 as its cutting. Chip load plays a big factor in a lot of ways, especially on the over all finish of the final cut....



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    Default Re: Advice re Milling Aluminium

    Hi Louie & Cyberave68,

    Yes, you are both correct, I was milling too fast and too deep on each pass. I had accepted the feed speed and step down values from the tool library in my cnc software. With more advice and checking with several 'wizards' I now have sensible values and the milling is much more successful. I now have a lube and air blast system to cool the tool and clear the chips.

    Cheers

    Gary



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Advice re Milling Aluminium
Advice re Milling Aluminium