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Flood Coolant

ddickey

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I bought some concentrated synthetic cutting fluid (Benchmark Sawlution II) that I was going to use on the lathe. I then heard that synthetic fluid is the worst for corrosion control.
On the fence now if I'm going to use it. Maybe just stick with a mister.
I wouldn't need it often but thought it would be nice to use instead of the mister.
Opinions?
 

benmychree

John York
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I like flood coolant, but it does have a downside; it seems to be degraded by (bacteria)?, Then it causes rusting, it seems that a film of oil settles on it, allowing the dreaded infection to set in; way back in the day, the scare of nitrosamines (nitrite amine formulated coolants caused the makers of coolants to reformulate them, instability being the result, it's been downhill ever since. I still use these coolants, but it's a pain to deal with. I remember that coolant skimmers and aereators were a partial cure.
 

Tozguy

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I gave synthetic coolant a try once. Water was mixed something like 10:1 if memory serves me well.
My chip pan was already wet with way oil and cutting oil. The coolant quickly got contaminated and made a mess. It makes sense to use coolant in a production shop where cutting rates and tool life are important but in a my hobby shop I will stick with cutting oil and avoid the mess.
 

talvare

Ted A
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I've had a little experience with the water soluble coolant/cutting fluid use in a non-production environment and found it to be more trouble than it was worth. It would grow some sort of slime in the coolant sump in a relatively short time and it also left a sticky residue on the machinery if not cleaned after each use. For my home shop I use Mobil 766 cutting oil as a flood coolant. I know it doesn't remove heat nearly as well as the coolants do, but it is satisfactory for my use. There are no issues with it going bad and it certainly keeps everything rust free.

Ted
 

ddickey

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I've had a little experience with the water soluble coolant/cutting fluid use in a non-production environment and found it to be more trouble than it was worth. It would grow some sort of slime in the coolant sump in a relatively short time and it also left a sticky residue on the machinery if not cleaned after each use. For my home shop I use Mobil 766 cutting oil as a flood coolant. I know it doesn't remove heat nearly as well as the coolants do, but it is satisfactory for my use. There are no issues with it going bad and it certainly keeps everything rust free.

Ted
Is there any fume/smoke issues with the Mobil 766?
 

talvare

Ted A
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Is there any fume/smoke issues with the Mobil 766?
Nothing significant. If I'm trying to remove metal quickly enough to generate a lot of smoking blue chips it will smoke a little but I've not had it be a problem and I'm generally not in a real hurry to get something done. I'm retired and this is a hobby for me :)

Ted
 

ddickey

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Was reading another forum and they were suggesting Mobil 404 I think it was. Have to do some reading.
 
Last edited:

pontiac428

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here is a link to the MSDS for Mobil 766 https://www.msds.exxonmobil.com/SearchResults.aspx or if that does not work try www.msds.exxonmobil.com
Yep, low risk. It's got BHT (the food preservative that saw a lot of use in the 1990's) in it as the antioxidant, and the oil itself is heavy straight chain, which our bodies tolerate. What isn't on the SDS is the sulfur compound, so that must be less than 1%, but it's also undeclared so I can't speak on the exposure risk. I am assuming Mobil wants to sell this cutting oil, so they probably left the nasty stuff out. I'm going to buy a 5-gallon bucket for my mill.
 

ddickey

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Looks like 766 has the highest viscosity of the 700 series.
 

ddickey

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What isn't on the SDS is the sulfur compound, so that must be less than 1%, but it's also undeclared so I can't speak on the exposure risk. I am assuming Mobil wants to sell this cutting oil, so they probably left the nasty stuff out. I'm going to buy a 5-gallon bucket for my mill.
1.6% sulphur is what I read.
 

ddickey

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Guys,
I've got myself some Mobilmet 766. There is only a screen between the chip pan and inlet into the coolant tank. Is this enough?
1575740993208.png
 

Bob Korves

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See if you have baffles in your coolant tank. The baffles are typically set up so the coolant enters one side of the tank, then a baffle forces the liquid under a baffle that also stands above the coolant level, then another baffle that forces the coolant over the next baffle with the bottom blocked off. There can be repetitions of the over under, (not so likely in a coolant tank.) The baffles alternately keep solids that are both heavier and lighter than the coolant from getting back to the pump. They work quite well, but must be cleaned out once in a while
 

ddickey

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What a mess. It's like taking a gallon jug of oil and dumping all around your lathe. sort of. Definately helps drilling, parting and tapping. But yeah it is a mess.
 

Karl_T

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pretty much covered the downside above.

But there are HUGE advantages too - MUCH longer tool life and faster cutting rates. With many special cutters costing over $100 each, I can put up with an aerator to keep the coolant fresh, and wiping my mill down when it gets sticky.
 

ddickey

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Yes I agree. Tool seems to cut much easier.
Since I'm using oil not really necessary to clean up much. So far the biggest grip I have is the cutting tool being full of oil when you remove it. Then you have to wipe it down before putting away. Also I'm not sure how healthy it is to have cutting oil all over your hands. 50/50 if I'll continue using it.
 

pontiac428

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Cutting oil is made up of bulky non-polar hydrocarbons and sulfides/sulfones, which does not penetrate the skin. The main effect is contact dermatitis, AKA oil acne. Very low risk. The metals we work with getting on our fingers and into our mouths is a bigger health concern. On the spectrum of chemicals we use in our home shops, the health impact of heavy oils is way down on the totem pole.
 
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