Thread: Dry Aluminium Cutting Problem
I'm always having issues cutting aluminium on my mill. The side which is climb milled is not too bad, but the side which is conventional kind of grows a furr of re-cut aluminium.
The thing is, I have a reasonably decent vacuum above the cutter and I've tried all different feeds and speeds (have G-wizard).
What I notice is that the issue becomes far worse as cutting time goes on and the piece heats up. Does anyone think the heat of the aluminium could be an issue? It seems like it becomes 'sticky' when it gets hot and bungs up my cutter and chips don't extract well.
I tried a 2 flute cutter today and it seemed to work better than the 1 flute but then suddenly got cloged as in the picture below.
Has anyone else experienced similar? I realise coolant is the way to go, but I don't really want everything to be messy and wet! Maybe a mist spray would be a good middle ground.
Below: This was extracted from the groove part way through cutting.
Thanks Jonathan, I'm glad it's not a problem specific to me. I'll have to think about the best way to do flood coolant. I went with the HDPE bed specifically so I could use coolant, but I know it will be messy.
Could I ask people to post up or link details of their coolant set-ups to give me inspiration?
You might find that mist coolant would be enough to reduce the heat build up since although it clearly wont conduct much heat away, the coefficient of friction between the cutter and the material is reduced so less heat is produced to start with. Did you use any lubricant at all when cutting the part pictured?
Aluminium is a bitch for clogging up tools. Plenty of cutting oil and/or coolant is the only way to reduce it.
One of those aluminium boxes with the O ring seal to make it weather proof. The lid is bolted to the end of the bed with a hole to drain the suds back in to the tank and type blue gasket compund so it doesn't drip.
In the bottom of the tank is a fibrous mat designed for filtering Koi carp pond water under a mesh to keep it in place. The oil goes down through that into a coffee machine pump I got on ebay. Spare pump on top of the tank. Then a hose to a magnetic nozzle.
I put it all together, switched on and found the pump was MUCH too powerful. Hence the knob at the back of the tank which allows most of the suds straight back into the tank.
I didn't use any oil at all. I've tried it in the past with WD40 and also water (not together) but it always gets whipped out the groove so fast! Even if I start out thinking I'll just use a tiny bit, the place gets flooded pretty soon. Yes the cut is much better, but I was under the impression dry milling was entirely possible.
I've ordered the bits to do flood milling. I just need to think about the best way to drain coolant from the bed.
I've also ordered a ripper mill so I bet that will extract chips better and not clog as much.
I got a bottle of this for coolant mixing - G/P Soluble Cutting Oil Coolant White Water 1 x 1 ltr | eBay
For dry cutting, you have to prevent the tool overheating so either add pauses to your program, or have a "dipping pot" of cutting oil on the bed which you return to after "x" time or take a rough cut first and no more than 0.1mm on the finishing cut. As you noted, climb milling always gives a better finish but may chatter more.
I cut aluminium dry all the time with just blown air and the odd squirt of WD40 and it's not a problem for me. I have mist and flood but both are messy. Flood obviously sprays every where and mist can be fumey depending on whats used. I only use them when finish is important but mostly I cut with just blown air.
What grade aluminium are you using because looking at those pics and the way it's grabbed and furred up it looks very much like the soft shity 1020 stuff you find in thinner sheets.
The grade of aluminium makes a massive difference and this soft stuff is like milling cheese strings and will defiantly need coolant.!
What size cutter, feeds/speeds and DOC are you using.?
I get the same thing with my customers trying to connect USB, as soon as the computer realises I am on the other end of the phone it knows the jig is up and gives in gracefully.
You might think it is just "air and the odd squirt", but experience tells you when to blow and when to squirt
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