Machining aluminum without coolant

You guys are both at IMTS! You should get dinner together.

I have one, I’ve been meaning to try using it for cutting but it uses a lot of air. You’ll need a serious industrial compressor just to power one.

I honestly don’t think it’ll be much better than a air blast in aluminium. Aluminium is already pretty good at removing heat, the two major issues that need to be resolved is chip clearance and galling prevention.

I had one in the early 2000s and I don’t know if they changed their design a bit to obtain colder air. IIRC, the model I had (same brand) stated it would drop the compressed incoming air by xx degrees (rather than imply you get -30 deg F). So, it was basically ambient air into the compressor, heat/cooled through compression/expansion dependent.

I needed cold air for a medical device I was prototyping machining as I couldn’t using any cutting fluids so the vortex gun was a good option for me. I “manipulated” the ambient air issue by running a long length of coiled air line into a big cooler filled with ice water. I also insulated the Locline plastic nozzle with neoprene tubing. I got SERIOUSLY cold air.

I had a compressor with filtered, dried air (med device comp). If possible, I’d recommend the same, or at least put some sort of inline drier/dehumidifier in place or the Locline may clog with ice. or at least reduce the flow.

Anyhow, I think for purposes of general machining and FIRST bots, a stronger air flow is needed and this device might not be the correct solution. I would buy one again, but only for specific applications as I had previously.

It does get seriously cold, that’s for sure. Were you cutting aluminium? It would probably work well when cutting something like titanium which has 1/12 the thermal conductivity of aluminium. Even with coolant the heat likes to pool up in the cutting area. Not fun.

Coolant is not really used for cooling anything down, it’s for lubricating the cutter so chips don’t stick. Also for evacuating chips.

Helps with surface finish because of this.

Priorities:

  1. Evacuating chips
  2. Lubricating cutter (so chips don’t stick)
  3. Cooling down the cutter/parts

Compressed air helps with #1, Mist helps with #2, Flood helps with #3.

Honestly I’d just use compressed air and call it a day. Maybe get a freshman to squirt WD-40/Alcohol/Whatever on the cutter

FRC parts are not going to space or anything…

The machining question has been answered nicely: airblast. That’s what I generally do with my shop’s PCNC 1100 and CNC router when cutting aluminum.

As for the cold saw, well, that depends on the saw and the material.

I use a DeWalt DW872 and can’t recommend it highly enough. No coolant needed for aluminum, steel, titanium, you name it.

Other saws I have seen and used are intended to use coolant all the time. I would consult those specific manufacturers for suggestions.

I was cutting several different types of plastic. The vortex also help me keep my tolerances since I was getting thermal expansion from the cut.

Ti is another beast altogether. I’ve machine a fair amount of 6Al4V and turning the stuff is easy. Holds tolerances with super nice finish and good tool life (insert tooling).
Milling however is much more difficult. I’m sure it has to do with the interrupted cut inherant with milling. Lubrication, not recutting chips, and coating on the cutter is key.
Good luck tapping if you’re not single pointing it. :sunglasses:

Thanks for reminding me why I bought my Vortex cooler in the first place. Did you find any reduction in burrs while using the cooler compared to dry machining the plastic? Even with the right endmill and proper speeds and feeds the burrs on UHMW have been tricky to deal with.

I don’t recall less burrs.
UHMW. Yuck
Use super sharp tools. If able, direct your cutter to push the Burr into the part. That will help reduce the size and make second op easier.

To add to this the Datron uses a Ethanol mist for non sparking metals. Ethanol is less toxic than Isopropyl (rubbing alcohol).

I’ve found that the faster your spindle is the less likely you’ll have issues with galling in aluminium. In my tests, flood coolant does almost nothing for a CNC router and is actually worse than a mister/air blast setup. It’s important not to conflate the cooling solutions of a CNC router (20k+ RPM spindle) and a CNC mill (typically ~3-7k RPM spindle stock). The Datron has a 60k RPM spindle meaning the coolant only needs to provide minimal lubricity and is mostly for providing cooling and chip clearance.

While I’d never try running flood on a router again, I actually quite like running flood coolant on our PCNC 1100. Because of it’s fairly limited 5140 RPM max spindle speed and our tendency towards smaller endmills and large WOC in FRC, flood coolant adds a lot of robustness to the cutting strategies we use which is particularly useful while learning.

While totally normal for us more experienced users, breaking endmills can be a really stressful experience while learning, for some students it might be enough to turn them off CNC machining altogether. For us some extra maintenance is a worthwhile trade off.

Flood coolant also has some advantages in a mill, properly mixed flood coolant can prevent rusting on the cast iron surfaces and is better at keeping chips off the way covers. We used a fogbuster for a while and it tended to throw chips everywhere and left a sticky residue within the enclosure.

On the other hand the PCNC 1100 flood setup does suck. The stock pump is weak and coolant tank is way too small so it constantly has to be topped up and re-checked with a refractometer, the pump quickly starves if it’s not 100% full. Worst of all it’s nearly impossible to remove for maintenance while full (It looks like they’ve resolved this on the new 1100M). A larger external tank has been on our to-do list for a while. And while I’d never run flood on a machine without a full enclosure the one on PCNC 1100 has pretty poor drainage, chip filtering and can be a pain to seal.

It’s also really crucial that an air blast/mister be pointed directly at the cutting tool which can be tricky to do on a mill when your changing tools and working with parts that require a lot of Z axis travel. Flood coolant is a little more robust in this way especially with a high pressure, multi nozzle setup.

You’d want some very good ventilation with that, to avoid awkward situations.

“I swear officer, I’ve just been machining all night!”