[sploo]

Short question: am I likely to get away with an air spray only to prevent aluminium gumming up a single flute spiral cutter?

Details: I use a K2 KG3925 CNC machine (~100kg all in - so very much in the hobby end of the scale) with a dust hood and vacuum for cutting wood and plastic (no enclosure), but I've previously milled some 1/4" thick 6082-T6 aluminium plate using a two flute 1/4" upcut spiral carbide bit. The results were OK (with no dust hood, and liberal spraying of WD40 to stop the bit gumming up with alum chips). However, it's not a pleasant job (WD40 all over a machine intended for wood and plastic, and getting lacerated with chips).

I've been asked to mill some parts from 1/2" thick plate (long job); and I really don't fancy standing over the machine for ages getting covered in WD40 and chips.

I've ordered some 1/8" single flute spiral upcut bits as I understand they're better for clearing chips, and I'm wondering if a compressor fed flexible spray nozzle (with air only) would be likely to work for preventing the bit gumming up with chips?

I could rig up a dust hood with the air spray nozzle, and a vacuum for hopefully collecting some of the chips being blasted out. My thinking is that I can then accept shallow depths of cut (and long run times) if the machine can just be left to cut without gumming up or spraying chips everywhere.

Is this likely to work, or is air only and no coolant/WD40 on aluminum a recipe for failure?

[joeavaerage]

Hi,
the problem with aluminum is its propensity to stick to the tool, called B(uilt) U(p) E(dge). The issue is that if chips are recut
they become locally hot enough to weld themselves together and/or the tool. Any process that removes the chips from the cutzone so that
they don't get recut will help your cause no end.

Air blast will do fine. Some people incorporate a hint of oil with the air blast which is a good solution.

I use flood coolant. A well directed liquid stream will flush chips out of the cutzone nicely and keep the tool and workpiece cool which is an advantage also.

Be careful about reducing the feed rate too much. If you reduce the chip thickness over much you risk 'giving the aluminum a good rub' and not producing a chip.
With any sort of luck you want the chip to carry away the majority of the heat of cutting, so you MUST produce a chip.

Craig

[RCaffin]

I am cutting aluminium all the time. I use a fairly good air blast to clear the chips, and a pulsed spray of a 3:1 kero/olive oil mix. Read up on MQL for details, and note that this is fast becoming mainstream. As it is pulsed, maybe once every 5 - 10 seconds, the parts come out almost dry.

Cheers
Roger

[TMToronto]

I have recently come across products called vortex cooling guns or 'cold guns'. There are several manufacturers and prices range based on quality of materials, but most are costly. It solves the problem of using fluids, but they can be noisy, and they can use a lot of air during operation. It would not compensate for incorrect feeds and speeds - from what I am learning a properly formed chip will carry away a lot of the heat produced by an effective cut.

[RCaffin]

I have not seen any evidence that cold guns can prevent BUE. They might do so, but they might not. Refereed references welcome (but not marketing spin).

I have seen a few cases where the use of cold guns has helped maintain dimensional tolerances with soft plastics.Mind you, I am not sure whether soft plastics can support tight tolerances in production!

I use MQL all the time, and it works fine. So do quite a few aerospace companies.

Cheers
Roger