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.

[JasonB]

On JasonB Said:

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

Hi Jason

I think before diving in and buying a mist machine I’ll try your suggestions. It’s really about the O1.

TBH I have a pretty big problem with swarf. Below is a pic of my shed and that whole area gets showered with chips, when I’m making the brass pieces. A blower might blow it in the other direction but there are still a lot of chips.  I have a vac setup that attaches my Henry hoover to a 3d printed collector mounted on the spindle bracket. It’s quite effective but noisy. Perhaps I will try to improve the nozzle so I creates more air movement around the cutter, in the hope of cooling it a little.

Alternatively I could rig up a blower, but my compressor is of the extremely noisy type.

I like the idea of more triangular tabs.

I’ll give it a try with the suggested settings  and see what happens. Worst case- broken cutter!

[John HaineParticipant @johnhaine32865]

My chip blower is an airbrush compressor with a small air reservoir, gives enough blow to clear chips from around the cutter and blows them into the right rear corner of the enclosure.

[Steve355Participant @steve355]

What is it specifically John? I have a Stanley branded compressor used for paint spraying, nail guns etc but it is unbelievably noisy , especially in a confined space.

[JasonBModerator @jasonb]

I have one of these under the bench here the CNC sits. So much quieter than the Machinemart one before it and a diaphram airbrush compressor. It can more than keep up with the air needed cutting in every 5-10mins depending on how much I have the blower working and I only know it has been running when the valve pops off when it is full as the CNC covers the small amount of noise it makes.

If you saw the video I posted yesterday I just use enough air to keep the area around the cutter clear. If you look towards the end one of the stills show sthe swarf which is a bit biase towards the left but that is more to do with the type of cut, if it were just a flat sheet you may be able to angle the blast across it but I need it to get down into the pockets. There is very little that gets beyond that trough around the table unless I’m using face mills.

[Steve355Participant @steve355]

I’ve been envious of those Hyundai “silent” compressors for a while. I think I bought mine the week before those came out. Perhaps I should take the plunge, but having a perfectly reasonable functional one that does the same thing but it just makes a lot of noise, it seems wrong to ditch it! But maybe that’s what I’ll do.

as for swarf distribution, it is getting absolutely everywhere. There’s just a lot of it, see the picture below, I am transforming 1” by half inch brass bars into these plane soles. I can’t see any practical way to do it without huge amount of waste – all that waste gets converted into chips and sprayed around my shed. Probably up to 4 feet in every direction.

 

[JasonBModerator @jasonb]

It might be worth just chopping up a cardboard box and seeing if something like the trough that I have would reduce the spread of swarf, it certainly catches most of mine. If it does then something more permanent can be made.

[Dave SParticipant @daves59043]

For slot cutting try counter intuitively running a smaller endmill with a deeper DOC, but an adaptive tool path.
I remember seeing a fusion Friday (YouTube Jon Saunders) on that subject

Dave

[Steve355Participant @steve355]

Ok… I think I am about to invest in a “silent” compressor as per Jason’s suggestion. I reckon there’s a direction I can get it to blow the chips where hopefully they won’t do too much harm.

but…. How does one attach a compressor hose to a typical Amazon blower? What fittings/parts are needed?

Thanks!

Steve

[John HaineParticipant @johnhaine32865]

What is a “typical Amazon blower”?

 

[Steve355Participant @steve355]

Sorry I was presuming that people use a coolant hose for just air instead of coolant?

[JasonBModerator @jasonb]

Typical Amazon ad with no sizes.

You will need to find the size of threads in the body, may be small 1/8″ BSP or given it’s Amazon may be NPT

I use push fit fittings and pnumatic hose, 6mm should be pleny large enough. Quick release from compressor regulator to a “tee” one side open to a 6mm line to a blow out gun. The other leg of the tee which has an on/off valve, then flow regulator and then 6mm from that to my mixer block and then out the nozzle. clear 4mm is the liquid feed. That way the blow out gun always works and I can have the blower nozzle on or off at whatever rate I want.

 

[Steve355Participant @steve355]

Thanks Jason, that’s very helpful. Is the “tee” regulator something you concocted yourself or are they commercially available?

[JasonBModerator @jasonb]

It came with my cheap Lock-line. Similar to this ebay offering

The hex base has a magnet set into the bottom and I added a second threaded hole in the base for the blow gun and the flow regulator after the on/off valve.

[Steve355Participant @steve355]

Thanks Jason, I will order one 👍

Steve

[Alan Wood 4Participant @alanwood4]

Beware the duty cycle rating of the compressor you buy.   The Bambi BB50 is branded as silent and delivers 50 litres per minute.   I am using a Fogbuster from Henck and on a long milling run the twin compressor motors get very hot.

[JasonBModerator @jasonb]

The Hyundai ones do get warm but still seem OK after 3-4hour machining runs and as they are off for probably 90% of the time a 10% duty seems OK.

This is likely due to the compressor delivering something like 8cfm FAD (not displacement) which is 225lts/min in metric and I’m not drawing off at anything like that rate.

[Author]

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