Between $100M-$500M worth of machine value is lost each year due to improper machine coolant management. Coolant management mistakes can decrease the working life of a machine up to 10% per year. Having a robust coolant management plan keeps your coolant from going bad and significantly reduces lost value and downtime of machines.
Is Your Coolant Going Bad?
There are a few telltale signs that your coolant needs maintenance or replacement. Coolant and cutting oils can become contaminated from tramp oil, bacteria, or metal shavings. Both bacteria and fungi cause coolant to become rancid, lose effectiveness, and can irritate skin. Here are common signs that it’s time to change your machine coolant and/or clean the sump.
- Excessive tramp oil accumulation
- Build-up of metal shavings and participles in the sump
- Leaky machinery
- Slimy bacterial accumulation
- pH is less than 8.0
- Machine coolant concentration is less than 2.0%
- Coolant is dark gray to black
- Rancid odor or sour like sulfur smell
Coolant Management Best Practices
The key to coolant management for your machine shop is maintenance which reduces the chances of your coolant going bad. You can extend the life of your coolant 2-3 times with good coolant management practices. Keeping coolant clean is easier and more cost-effective than having to replace it. You should continuously be skimming, cleaning regularly, and screening out metals particles where the coolant enters work station sumps or exits from holding trays. Additionally, you should be checking and tracking concentration levels, any sign of any bacterial growth, and monitoring pH balance daily to get the most out of your coolant.
Water-soluble or miscible cutting fluids are rather alkaline and have a pH of 8.6 or higher. While this helps prevent corrosion and controls microorganisms, it does take a toll on paint and rubber seals. To minimize the wear, wipe down machines after each shift, inspect seals and wipers and replace as needed, and install a skimmer on each machine to eliminate tramp oil.
Maintaining Proper Concentrations Levels
By closely monitoring and recording the condition of the coolant, you know when it is time to add more coolant or additives. When bringing your concentration levels back into balance, you should never add straight water or concentrate into the sump. Instead, add a weak dilution that is half of the goal concentration. If the goal is 10%, then add 5% concentration. If possible, for your water, use a deionizer or reverse osmosis system and don’t use softened water. Minerals in the water can remain behind after water evaporates, and overtime can leave residue on machine surfaces. Mineral build-up in the mixture can also cause poor blending.
Select high-quality coolants that last longer and try to limit the number of different coolants you use in your shop. Buying coolant in bulk helps reduce costs. Make sure your parts cleaning systems are compatible with the selected coolant. You should be sanitizing sumps and machinery regularly, in addition to removing old coolant and sludges. If coolant is idle for extended periods, use an aeration kit to circulate the coolant to prevent excessive anaerobic bacteria formation. Lastly, train employees to keep trash, solvents, tramp oil, and other foreign material out of the coolant system.
Dirty coolant not only reduces its effectiveness, it also hurts tool and machine life. If the concentration level drops below the coolant manufacturer’s minimum, it can cause rust on the machine tool. Dirt or fine particles in the coolant can become abrasive, scratching paint and glazing on a machine’s windows. Lastly, dirty coolant can put excessive wear on pumps and filters. By implementing a coolant management plan, you extend the life of coolant, tools, and machines.