DIRTY coolant reservoir!

machinistnoob

machinistnoob

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Good evening everyone. Just bought a Lagun mill. It's clean and in fantastic shape. Before placing it, I opened up the rear access for the coolant and pump. What I found was... disturbing. Maybe it's normal, and that's why I'm floating this to you guy's.
Inside was an inch of sludge, swarf and chips. The consistency of a thick batter. On top of that, was an inch of oil-ish fluid. I should have gotten a before pic. I'm pretty sure that I'm the first one in there since the factory buttoned it up. I removed the pump, oil, sludge, chips and thoroughly cleaned and de-greased.
So, how come no filter of any sort? Not even a sump for the large debris? Chips can flow from the table to the reservoir to the pump and back to the table? I did place some strong magnets where the fluid deposits, but what about non ferrous metal? Or is this just not an issue? Thanks in advance.
M. Noob
 

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It’s interesting you mention this. I opened up my FT-2S the other day and the sump appeared to have what looked like oil saturated sawdust in it though I don’t think that’s what it is. And lots of oil, not what I was expecting. No chips though.
 
Coolant systems often don’t receive the attention that they should. Coolant can be a game changer, allowing significantly better performance (be it removal rates, surface finish, tool life, . . . Some other benefits too). The machine manufactures add the coolant system because customers want it and will pay for it. That some machine owners don’t take care of that system is to their detriment ( granted if the machine is going out the door, they may not care about it anymore).

I have picked up most of my machines as very sad projects. Those that are fitted with coolant have been disgusting down in the coolant tank.

True, looking after one more area is a chore. I don’t run coolant on the manual machines (just various squirts, sprays, drips or brushes) but a maintained system on the surface grinders and CNC equipment (oil skimmer, monitor concentration with a refractometer, periodically clean tank and replace the fluid).
 
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What you found is unfortunately more common than not. Everyone in the shop loves what coolant can do for the processes, but no one wants to be the one that gets assigned to clean the tanks and replace the coolant. Cleaning the tanks is one of the nastiest jobs in the shop and is usually assigned to the lowest employee on the totem pole. We had several coolant capable machines in the shop where I worked. I was the one that got assigned the job a couple times. It took hours to drain the rancid mess, and in some cases days to scrape out the stuck-on swarf and dried coolant.

I currently have 4 coolant capable machines in my shop. The only one that I use coolant in is the cold saw. All the others work fine without it, and I don't have to deal with the coolant getting rancid and swarf stuck in the reservoirs and pumps. All of the machines coolant systems were in similar shape to what you describe when I got the machines. It literally took days to clean each one. Two of the four had to be completely disassembled and taken to the DIY car wash to clean them out.

As for filters none of my machines have them either. Two of the saws have compartmented tanks. There's a baffle about half the height of the tank. The coolant drains into one side and eventually rises high enough to spill over the baffle to the pump side of the tank. The swarf settles out in the return side before the coolant flows to the pump side. The pumps do have a screen on the pickup end to keep large chips and pieces of swarf from picked up.

The cold saw doesn't have a baffle in the tank. It has a screen in the drain trough to keep the big stuff from going into the tank, and a screen on the bottom of the pump to minimize what it will pick up. In this particular machine the chips/swarf is large enough that 99% of it can't get through the screen. That being said there was about an inch of grit in the bottom of the tank when I go the machine. The machine was built in 2011 and I purchased it in 2022
 
On our cylindrical grinder, we installed a dual spin on filter assembly to catch anything that try to make it up to the wheel. Tiny little scratches in the finish surface were showing up on the rolled materials. The 70+ years old machine has three tanks that flow from on to the other. This will allow the junk to fall to the bottom in the first two tanks, but some makes it to the pump in the last tank. 60 gallons of mucking smelly fluids every 6 months or so, depending on the treatment added to it.
Our Haas CNC machines have large tanks on the bottom and it is not fun to empty either.
Pierre
 
When I bought my Tormach PCNC, I also bought their coolant system. After a year's use, I had a similar situation to the OP. I don't use my mill often enough to justify maintaining a flood coolant system so I just cleaned up the mess and it is sitting dry.

Most of the oil is coming from the lubrication system. An oil skimmer will help to reduce the sludge formation. I also modified the screen on the tank which will improve capture of chips but there is little that I can do to catch the fines. A filter similar to those used to remove particulate matter from drinking water would work but it would have to be installed on the intake side as it would require some pressure to force the coolant through and it would probably clog up fairly quickly. For steel swarf, a magnet would help as well but you're SOL for aluminum and other non-magnetic materials. I didn't have a problem with a rancid odor but after a few weeks, the coolant was pretty disgusting..

Maintaining coolant concentration was also an issue. I keep the relative humidity in the shop between 30 and 50% so evaporation is an issue. If the system hadn't been used for a week or two, adjusting the concentraton would be the first order of business before any new machining. I use a refractometer to maintain the desired concentration, topping up as needed with water. When I get a new concentrate, I mix up a set of reference samples over a concentration range from about 20% below to 20% above the target concentration for direct comparison.
 
Cleaning my Lagun's catch system is on my long list of stuff to do. I poured a quart of engine flush (repackaged off-road diesel) in my basin two weeks ago to start on the crud. I doubt I'll get mine as clean as yours, that is some impressive work there.

Cutting oils work by settling out suspended metal fines in the sump. It's where they are supposed to end up. I suppose you could put a nylon stocking over your drain grate in the catch tray if you want to delay the inevitable. Maybe a fine drain strainer too.
 
pontiac428 said:
Cleaning my Lagun's catch system is on my long list of stuff to do. I poured a quart of engine flush (repackaged off-road diesel) in my basin two weeks ago to start on the crud. I doubt I'll get mine as clean as yours, that is some impressive work there.

Cutting oils work by settling out suspended metal fines in the sump. It's where they are supposed to end up. I suppose you could put a nylon stocking over your drain grate in the catch tray if you want to delay the inevitable. Maybe a fine drain strainer too.
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Thank you! Only took a few hours.
-Tilted machine towards the rear
-Scooped and scraped out the crud.
-Absorbed remaining oil out with an old towel
-Placed magnets around the bottom added a degreaser called oil eater (great stuff $13 at Amazon!) and hot water and scrubbed with a toilet brush.
It was easier than expected. And the oil eater cuts right through that stuff.
 
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