CNC Coolant

[Steve355Participant @steve355]

Hi

I am at a point in my CNC journey where I really need to find a coolant/lunrication solution. I have a home brew Chinese 6040 with an inch thick piece of tooling plate for a bed and it works very well for brass (which will be my main material). But it could do with some lubrication / cooling that doesn’t require me to stand next to the machine with an oil gun. I like the sound of IPA for this – I’m a little nervous about explosions, but it’s in an environment where water or oil are unwelcome.

I read on the fog busters website about the virtues of spray rather than mist. I don’t know if this is marketing , or important.

There are some cheap systems on Amazon. I wonder if these are any good?
http://Lubrication Spray System 220V Spray Cooler Coolant Pump Oil Mist Sprayer for Machine Tool Cooling 3L Tank Air Filter with Cooling Water Pipe Nozzle https://amzn.eu/d/62WQD7T

But I am about to move on to tool steel (O1). I’ve had a certain amount of success with this before (see pic) so I know it can be done. But it worked with me standing next to the machine with a cutting oil gun – which I want to avoid. And ideally it wouldn’t be oil at all due to the mess. But with steel, I am worried about sparks with IPA – and I really need to confidently leave the job going while I do other things.

If anyone has any useful info or ideas, that would be great.

Thanks

Steve

Brass

 

 

[John HaineParticipant @johnhaine32865]

I think IPA would be a disaster in waiting! During a long job vapour will build up and it would just need a spark in a light switch or motor commutator and boom! I suspect your insurance company might look, askance at the resulting claim too.

[JasonBModerator @jasonb]

As I said the other day, the likes of Datron use IPA without problems or it getting above recommended levels

The IPA is more of a coolant and mixed with the air which cools as it removes the chips. If you want lubricant then that is really going to need a liquid which if used in a MQL system does not use much and could be as low as 2mls per hour.

My own system will add 10 to 30mls per hour which at the lowest setting will keep aluminium from sticking to the tool but can be would up if needed and does not fill the room with fog or leave the swarf dripping in lubricant. I use a neat fully synthetic cutting fluid.

Have a look at this thread on MEM and also look up the commercial “Microdrop” that Dave mentions (need to join to see all of the images). Mine and Vixens are versions of the “coldend” his more so than mine now he is using the same pump

Having said that I tend to cut steel including silver steel dry.

[JasonBModerator @jasonb]

Have a read of this from Datron about using alcohol, not really any good for your steel parts.

Dry cutting silver steel. I’d be going at it faster and with an adaptive to start these days but I had only just go the machine then.

[Steve355Participant @steve355]

hi Jason – Interesting. Looks like I’m asking the wrong question. In fact my dry cutting brass is ok. I am currently cutting very little aluminium. In fact, what I really need is better chip evacuation either through blowing or improving my chip vac system.

When I did the experiment with O1, TBH I didn’t expect it to work. it generated a lot of heat, and smoke from the cutting oil. I’m was expecting work hardening to be a problem but it got through it, even with a cheap amazon endmill. But it didn’t seem sustainable, if I want to do a lot of it, which I am hoping to.

You can see from the pic what I need to achieve – a simple profile in a 1/8 sheet of O1. What type of bit, rpm, doc, feed rate etc would you use, if you wanted to cut it dry?

 

 

 

[Julie AnnParticipant @julieann]

I use flood coolant on my CNC mill for all materials other than cast iron and plastics. My coolant is Hysol XF, which is a soluble oil, on all my machine tools. On the CNC mill it is as much about swarf removal as cooling/lubrication.

This traction engine expansion link and die block, in gauge plate, was made for someone else on my CNC mill about 14 years ago, for scale the gauge plate is 1/2″ thick:

The CNC toolpaths were programmed to leave the slot about 0.02mm undersize and the die block 0.05mm oversize. The slot was finished by draw filing using a Hoffman roller as a gauge. The die block was then draw filed to fit.

I use IPA for cleaning my 3D resin printed parts. It’s not cheap and would be total loss for CNC machining so I wouldn’t use it on the CNC mill and/or in an enclosed space.

Julie

[John Haine]

On John Haine Said:

I think IPA would be a disaster in waiting! During a long job vapour will build up and it would just need a spark in a light switch or motor commutator and boom! I suspect your insurance company might look, askance at the resulting claim too.

I’m with you John a disaster in the making, IPA [alcohol?] may be ok for Aluminium but nothing else. For O1 I would use a water based coolant either flood or mist, pros and cons to both.

Tony

[JasonBModerator @jasonb]

Several points there.

– Chip Evacuation. Really two options which are washing it away with flood coolant as Julie uses but you need really a full enclosure, etc. The other option that I use is to blow it away, if you look at most of my videos you will see the LocLine which as a 4mm OD tube inside and then a 1mm OD brass end which ups the velocity so you don’t need much air or pressure which means a smaller quieter compressor can be used. I have it set to keep the area around the cutter clear not the whole table so it does not blast the swarf all over the place.

– Lubrication. On small aluminium jobs I will brush on a bit of paraffin but larger ones I add the lube to the air otherwise I cut dry. One problem with just adding an oily neat lube is that it is sticky and will be counter productive when it comes to getting rid of swarf as it will make the chips stick in the slot and to the tool and you then start recutting them which is not good

– Cooling. Adding small amounts by brush will not really do much to cool the job or tool, as you have found it just cooks the oil or if using soluable oil will turn the water content to steam ready to condense out on other cold metal surfaces in the workshop.

– So in your case I would say if you keep the lubrication to a minimum applied with the air or just use the air it would do the job.

I don’t tend to do that much cutting out from sheet and have still not found he ideal approach but generally the feed needs to be less than when you are just using teh side of the cutter this is due to zero chip thinning. Don’t use too small a cutter and slow the ramp feedrate which combined with triangular tabs won’t see the tool plunging quickly down after each tab. Do a final finish pass at full depth which should eliminate any marks left as the tool steps down and also give a more accurate part as the tool is not being pulled sideways by the full width cuts.

Starters for 10 say a 3-flute carbide cutter at 4mm dia. 5000rpm. Do it in 4 passes a little over 1/64th each with a final clean up at just over the full 1/8″ thickness. Feed less than you would for side cutting, try 300mm/min

This is mild steel with similar parameters as above, just air to clear the chips

[HuubParticipant @huub]

On the lathe I use water diluted oil (10% oil) for lubrication for all drilling, parting, tapping and threading operations in steel, aluminum and plastics. To avoid aerosols, I use an MQL system with a car fuel injector that generates “large” drops of lubrication fluid. A garden sprayer is used to supply low pressure coolant to the injection valve so no compressed air is needed.

On the mill I planned to use compressed air to evacuate the chips and my MQL injection system to add minimal lubrication fluid to the compressed air.

Flood cooling would be better, on the lathe and on the mill, but that is to messy in my tiny hobby shop.

IPA is out of the question, to flammable and to unhealthy fumes.

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