Monroe Fluid Technology - Maintenance Tips

Technical Info

Maintenance Tips

The following tips can help you get the most performance and functional life from your metalworking fluids. This page will be updated on a regular basis.

AERATION: Provide aeration of coolant during extended periods of down time. An air lance with 5 psi pressure or a fish tank bubbler allowed to bubble gently in an idle sump is often sufficient to prevent excessive anaerobic bacteria formation.

SOLIDS: Another area for concern is the level of chips, fines or swarf in the sump. Quantities of these small particles can provide an enormous surface area for bacteria to attach themselves to while at the same time creating “dead areas” where coolant cannot circulate. There are many methods available for removal of these particulates such as magnetic wheels, conveyors or indexable filters. In general, the less solid material in the sump or system, the better.

WATER QUALITY: Due to ordinary evaporation, a metalworking coolant system acts like a still, evaporating water and leaving hardness minerals behind. Over time the mineral build-up can result in poor emulsion (mix) stability, heavy residue on machine surfaces, corrosion problems and a host of undesirable conditions. A good rule of thumb is to use tap water for the initial charge and the purest water available for makeup solutions, thus minimizing the level of mineral buildup. (A certain amount of water hardness can actually be beneficial, by helping supress foam levels.)

PROCESS OILS: When selecting process oils (hydraulic fluid, way lube and spindle oils), investigate the use of non-emulsifying oils. These oils are not all created equally. Process oils which emulsify into the coolant can dramatically reduce coolant life. Choose oils which readily separate from the coolant, where they can be easily removed.

SAMPLING: The best location for obtaining coolant samples is from the coolant nozzle, which will provide the most representative sample. If machine tool has been idle, allow pumps to circulate coolant several minutes prior to sampling. Never dip a sample bottle into a coolant sump that is covered in tramp oils.

RECYCLED COOLANT: When recharging a machine sump with recycled coolant, mix at a 50/50 ratio with a fresh coolant mix to ensure replenishment of any depleted components.

WATER QUALITY: Coolant in machine tool sumps is generally comprised of 5 – 10% coolant concentrate and 90-95% water. Insure that the water supply used for coolant mixes is of good quality, i.e. low in chlorides, sulfates and nitrates as well as low in hardness value.

PROPER MIXING: Use a proportioning device to ensure proper mixing of coolant with water. These devices thoroughly and accurately mix the coolant with water before introducing it to the sump. As a rule of thumb, run makeup concentration 1/2 as strong as initial charge, to compensate for evaporative losses. Never add coolant concentrate directly into the coolant sump.

RECORDKEEPING: For each sump or system, maintain a record of coolant and water additions, as well as any testing results. This will ensure that product is being properly maintained and will help identify trends such as evaporation and makeup rates for the system.

CLEANOUT: When cleaning out machine tools, remove conveyors and clean out any debris, swarf or chips that may be trapped beneath. Failure to perform this procedure will reduce the life of the new coolant charge.

CLEANOUT: Use a high-quality machine cleaner, such as ASTRO-CLEAN A, to ensure that the coolant sump is clean and biological activity is neutral before charging with coolant. This will greatly extend the useful life of the coolant.

TRAMP OIL REMOVAL: Ensure that Tramp Oils (hydraulic fluid, way lubes or any process oil not originally part of the coolant) are continually being removed from the surface of the coolant sump. These oils can provide food for bacteria, thereby reducing the life of the coolant. FIX OIL LEAKS IN MACHINE TOOLS!

REFRACTOMETER USE: Use a refractometer to check coolant concentration on a daily basis. Before checking, ensure the refractometer is calibrated to zero (use the same water that is used to mix coolant). Maintain concentration at recommended levels.

COOLANT pH: Use pH to help determine the useful life of the coolant. The pH scale ranges from 0 to 14, with 0 being highly acidic and 14 being highly alkaline. Water is neutral at 7.0 pH. Metalworking fluids are healthy and viable in the range of 8.0 to 9.2 pH.