What to do when foam happens to you
Air does not lubricate. Foam in a metalworking fluid is a mess and a nuisance, but more importantly it makes the coolant useless by interfering with the lubricity and cooling features of the fluid. Unfortunately the high-pressure/high-volume coolant systems used in today’s manufacturing create ideal conditions for foaming. A high-volume system can operate at 200 gpm, turning a 100 gallon sump over in 30 seconds. And a high-pressure system operating with 2,000 psi can rip a roof off a building. With all this moving, shaking, and spraying it isn’t any wonder that so many manufactures have problems with excessive foam.
Causes of foam fall into two main categories, chemical and mechanical. When diagnosing your foaming problems it is best to start by simply checking your concentration and sump level. If these check out then a more in depth investigation is necessary.
Below are some common causes of excessive foaming, before changing your coolant take a look here to diagnose the problem.
Chemical Causes:
CAUSE: The metalworking fluid concentration is too high.
FIX: Analyze the concentration (a good refractometer is an investment that is worth every penny) and adjust back to your recommended concentration. Try to identify the cause of the increase in concentration.
When adding makeup do you add coolant concentrate and water directly to the sump instead of mixing it before hand?
Are your metering devices working accurately?
Has your coolant maintenance schedule been followed properly?
Are your operators properly trained to identify and correct minor problems before they get out of hand?
Answering these questions will help you avoid concentration problems and minimize foaming in the future.
CAUSE: The water you use may be too soft to use with your coolant.
FIX: Do a water analysis (many water-treatment companies will do a free analysis to help sell their services). If your total water hardness is less than 50 ppm switch to a coolant more well-suited to soft water environments. You can also consider artificially hardening your water with calcium or magnesium. If foam is a consistent problem when charging a new sump it is recommended that you use 50 to 100% tap water in your initial charge to give your water some hardness to prevent the first week or two of foam.
CAUSE: Improper additives such as mop water, cleaners, or bleach where put into the sump.
FIX: Unfortunately these improper additives usually destroy the integrity of the metalworking coolant and require a change out of the coolant. On a temporary basis the foam issue can be fixed with defoamer, but you won’t know if the improper additive caused rusting, tool damage or decreased lubrication.
Mechanical Causes:
CAUSE: Restriction of the coolant flow in the machine or sump
FIX: Check for puddles of coolant blocked by chips or machine pass-ways. In the simplest situation the chip blockage can be removed and allow free flow of coolant back to the system. In more complex issues you may find that the machine just has too many restrictions to allow proper coolant flow. In this case you may need to add some more holes for coolant flow. Be careful to increase the flow without removing the chip-control feature of the machine.
CAUSE: Low coolant level in the sump.
FIX: Add coolant make-up to the sump only after followed the step above to ensure that the coolant level is actually low and not just trapped elsewhere. To avoid overfilling the sump remember to shut all coolant pumps off and allow a few minutes for the coolant to make its way back to the sump before adding make-up.
CAUSE: Over use of coolant nozzles and pumps
FIX: Most modern machines have many very useful coolant nozzles and jets intended to clean the chips from the machine. However, in many cases there isn’t enough sump capacity to run these jets/nozzles at the same time as you run the through-tool coolant and external cut zone coolant. Some simple adjustments of the programming can prevent starving the pumps of coolant while making good use of the features. Operate chip clean-out systems in short spurts periodically or during breaks in the cutting action.
