Dry milling aluminum in general and 5154 in the hobby

[Jasonb]

I'm not an engineer either, just a hobby user who is generally quite practical. It's quite happy machining steel and iron provided you don't go mad. I seldom use anything larger than 6mm dia cutters except when surfacing larger aluminium parts.

On steel for adaptive cuts I use a 6mm dia 3-flute cutter run at the maximum of 5000rpm, Ae (sideways depth of cut) 0.6mm which is 10% of cutter dia and that applies to smaller cutters too. Ap (vertical depth of cut) 6mm eg 1xD or a bit less if it works out as a multiple of the overall height rather than say 3 cuts of 6mm and one of 2mm on a 20mm part I'll do all four cuts at 5mm each. I leave 0.3mm for finishing.

For finish contours around the outside of a part I'll again use the Ap of 6mm though may go a bit more if the part is not too thick such as 8mm and do one pass taking a 0.2mm cut and then one of 0.1mm

If it's more of a 3D shape then after the adaptive I will use a 4mm or 4mm 4-flute ball nose cutter which is better than the usual 2=flute as you can feed twice as fast for the same given chip load. Stepover will be in the region of 0.2mm to 0.25mm depending on the job running at 5000rpm and 600mm/min feed

I'm not so keen on doing just a contour around the pass where the tool cuts at it's full width and in shallow passes as it doe snot sound as happy and you also wear just the end of the cutter rather than spread the wear over a longer length of flute. So will generally use the adaptive route to get the waste off the part unless its a sheet metal job eg from 3mm or less sheet.

These figures are for Carbide cutters. I get quite a few from APT, the odd one from ARC and the ones that do the adaptive are NC from Cutwel. The NC stands for New Century which is the Chinese factory owned by YG-1 so still made to a good standard. Drilling is usually Dormer A022 HSS Stub Drills.

All climb cuts, again the machine sounds so much happier climb cutting that conventional.

I usually put the details of the cut in the captions that come up during the video or in the comments below so that should give you an idea of what works.

 

[Jasonb]

**** (Richard) the air runs all the time to keep chips away from the cutter as recutting chips will seriously reduce you cutting tools life. Not so bad when cutting around the edge as most gets thrown clear but when doing pockets, slots or helical ramp cuts it builds up fast.

It's really not a large flow of air so chops don't go far. Larger diameter tools have far more effect on how far chips travel than the small flow of air through that tiny nozzle.

 

[Richard Hed]

**** (Richard) the air runs all the time to keep chips away from the cutter as recutting chips will seriously reduce you cutting tools life. Not so bad when cutting around the edge as most gets thrown clear but when doing pockets, slots or helical ramp cuts it builds up fast.

It's really not a large flow of air so chops don't go far. Larger diameter tools have far more effect on how far chips travel than the small flow of air through that tiny nozzle.

I get that. It is not your practice that I am talking about. It is the practice of when the chips are laying on the lathe bed, or mill table when the part is done, some people just blow the remaining chips all over the place. I wonder why they do that, as sukking them up with a vacuum is easier than handling the chips a second time off the floor and in shelves and all that.

Cooling and keeping the chips out of the cutter while it is cutting is a different matter.

 

[Toymaker]

Yes, of course, what I am saying is do the cutting, then vacuum up the mess before blowing it clean. that way you get less chips jammed in the machine and you also have less sweeping up and dusting shelves and so on. I would never leave a vacuum on--too noisy

By using a few PSI of air pressure to continuously blow the chips out of the end mill, my end mills last longer, are not as likely to break, and when cutting aluminum or other soft metals, don't gum-up as quickly....because my end mill isn't re-cutting the chips that would otherwise still be laying in the cutter's path.

 

[Richard Hed]

By using a few PSI of air pressure to continuously blow the chips out of the end mill, my end mills last longer, are not as likely to break, and when cutting aluminum or other soft metals, don't gum-up as quickly....because my end mill isn't re-cutting the chips that would otherwise still be laying in the cutter's path.-

After many years of not being able to afford a decent air compressor, I finally managed to get one from Harbor F. I am in the process (very slow) of getting a mill set up to run (ordered a VFD a few minutes ago). I will use this technique, possibly with a venturi-water mist setup. Also, I vacuum up my chips when done cutting to keep the mess off the lathe and mill.

At the moment, I needs to take the 3-jaw on the lathe apart to clean and inspect. I don't know if there are chips in the scroll or if the castings and milling are a problem, but the thing is difficult to tightne/loosen at certain points. I DIDN'T blow any chips in because I didn't have a compressor until recently.

I've been wondering if it is feasible to use a vacuum (one without too much noise, that is) on the open end of the spindle near the change gears. It might help with some chips abut not others. It also might be more problematic than useful. Anybody ever heard of such a thig?

 

[ShopShoe]

Richard,

I think you'll find a few things to note when you take your chuck apart. Show us a picture of what you find.

I've only used compressed air a few times and it causes more mess than it cures. The only use I still have for blowing air at any pressure on cutters in use is when cutting pockets on the mill: It's true you don't want to keep cutting the chips over and over and having them fill up the hole.

I've used air and I've used vacuum on the gear side of the spindle and my experience was either one can cause more chips to end up lodged inside the chuck. (To be clear, I used one OR I used the other, not both at the same time.)

For anyone considering using a vacuum to grab chips while machining, please work safely and consider what is going into the vacuum tank. Someone said years ago that vacuuming hot things into a tank with combustible or flammable materials is creating a forced-draft furnace.

I may still use air or vacuum from time to time, but only after thinking it through in advance.

--ShopShoe

 

[kf2qd]

I machine aluminum without coolant, Here in the US WD40 or equivalent is commonly used, not sure of availability in the rest of the world, you probably have a local favorite. It used to be recommended to use kerosene, but that is harder to get these days. A very light oil, sprayed on as needed will keep the chips from sticking to you cutter, and because it is a light oil, most of it will evaporate and leave your parts clean.

 

[EtheAv8r]

Jason: Thank you for sharing your KX3 feeds and speeds info, it was very kind of you to take the time to provide this, and it will give me confidence to mill steel on my KX3.

Although only machining aluminium on the KX3 I am generally standing over it with a Karcher workshop vacuum hose in one hand and a small brush in the other applying cutting fluid once or twice per pass, and dabbing in with the vacuum to suck up chips after the cutter is well out of its way. This works well and is safe in the way I do it, but it is very noisy and time consuming, hence my interest in the blower/lubricator used by Jason.

Currently researching suitable parts/options and an appropriate small compressor for the unit. I might simply get the "cold-end" system pointed out by Jason, as it will ensure that it works without time consuming or hit and miss experimentation.