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by Robert A. Picek
Lormar Reclamation Service

AUGUST 2002:

            The benefits of operating central coolant systems at high production machining operations are numerous and have been well documented through the years.  The cost to monitor and maintain the condition of coolant in one large coolant system, instead of numerous smaller systems, is drastically reduced.  Well designed central systems with adequate coolant volume and contamination removal equipment may run from months to years on the same coolant charge instead of weeks.  Thanks to the proliferation of coolant central systems, millions of gallons of coolant have not been disposed and thousands of hours of lost production for downtime have been avoided.           

In spite of a company’s best efforts at maintaining their coolant at optimal levels by controlling biological contamination, removing tramp oils, swarf, metals and dirt, adverse conditions sometimes develop which cause serious problems with coolant performance or conditions in the plant.  Machine tool damage, parts residues or other parts finish problems, foaming, plant smoke, odor and loss of the ability to control biological levels are at the top of the list of the conditions that cause concern and frequently result in system dumps.

The root cause for many of these conditions can usually be attributed to contamination of the coolant as opposed to the “break down” of the coolant.  Tramp oils, even at very low levels, can contribute to a host of problems for central system operators.  The obvious problems of plant smoke and oil mist, associated with the burning of tramp oils at the critical point of machining, can be reduced or eliminated by maintaining very low tramp oil levels.  In addition, maintaining biological control of the coolant is simplified when tramp oil, the “food” for most bacteria, is controlled. 

Many manufacturers don’t always associate tramp oils with the other problems they cause.  Tramp oil build-up can increase coolant viscosity and change the characteristic of particle contaminants.  Particles in oily systems may begin to float within the system or become too sticky to build up a filter cake on filter media.  Unless removed, the tramp oil may cause a loss in the efficiency of the central system’s particle filtration system resulting in excessive solids.  Parts finish and staining problems and tool damage can result.

Disruptions in coolant chemistry may also result from the presence of tramp oils.  The function of some coolant additives, especially emulsifiers, friction reducers and de-foamers, can be negated or otherwise adversely affected when they clash with additives contained in other oils used in a plant that may find a way into the coolant system.  Problems have been documented where as little as 50 gallons of certain lubricants contaminating systems up to 20,000-gallons caused the loss of the oil rejection characteristics of a coolant.  Instead of tramp oils being rejected, they were drawn into the coolant resulting in failure of the solids filtration system.  This, in-turn caused severe tool damage and parts-finish problems.  Severe foaming has also been attributed directly to tramp oil related chemical contamination.  The effects can range from simple system overflows to loss of performance due to air entertainment.

Solid contaminants can also wreak havoc with central systems.  The deleterious effects of large abrasive particles, dirt, swarf and metals are well known.  Considerable filtration equipment is typically dedicated to controlling their levels.  Under normal operating conditions, typical solids control systems do an excellent job of removing these larger solids.  Not all systems however include filters capable of removing the very fine, non-filterable solids generated in machining operations.  These very fine, sometimes sub-micron solids, when allowed to build up, may dissolve or combine with oils or other constituents to form metallic soaps and greasy residues.  Over time, the levels of these soaps and greases increase and can begin to coat parts, tools and machine ways and may result in considerable lost production and foaming.

 Since these problems usually seem to occur instantaneously and can be severe, central system operators understandably look for the quickest possible solution.  While coolant dumps usually correct the problems, they are not always the quickest solution, and hardly ever the most cost effective.  Numerous unnecessary coolant dumps occur.

Companies that continuously monitor the condition of their coolant may be able to establish that certain levels of contamination correlate with the development of certain problems.  Examples may be when solids exceed 500 PPM, parts finish and foaming problems develop, or, when tramp oil exceeds 6%, plant smoke, odor and loss of biological control occurs.  Establishing this correlation may indicate that the problem is correctable and that by effectively removing the offending contaminates periodically, the problems may be avoided.  The result can be the elimination of unnecessary dumps and unwanted interruptions in production.

An alternative to system dumps exists that has proven to solve on-line coolant contamination problems in those situations when a system dump is not absolutely necessary.  Instead of allowing the coolant to gradually deteriorate due to increasing levels of contaminates, the coolant is purified to remove the offending contaminates to interrupt the cycle of degradation.  When performed effectively in a timely manner, this technique has proven to restore coolants to an excellent condition without shutting down.  In many cases, coolant service life has been increased by several cycles utilizing this technique.

Those companies with the longest coolant cycles continuously monitor fluid concentration, viscosity, pH, tramp oils, solids, and microbiological contaminant (biomass or viable count) levels.  Plant personnel’s observations of coolant color, odor, the severity of plant smoke and the effectiveness of their filters are also documented.  When the information indicates a buildup of contaminates has occurred and a disruption is imminent, the system is purified.

Some companies utilize Lormar Reclamation Service, an outside contractor with mobile coolant purification equipment.  Lormar’s mobile system and expert personnel able to continuously operate the equipment at optimal efficiency are dispatched to the facility.  Within minutes of arrival, the mobile equipment is connected to the plant electrical system, supply and return hoses are dropped into the central system, drums or a tank are designated for separated waste, and processing of the coolant starts.  A side stream of coolant is processed through a combination of technologies that rapidly and efficiently remove solids and tramp oils from the coolant.  Continuous monitoring and control insures the best results, in the shortest time, with the least amount of waste.

Tramp oils, which consist of broken down oily components of the original coolant package, way lubes, hydraulic oils, metallic soaps and other lubricants that leak into the coolant are typically reduced to about 4/10ths of 1%.  Solids, which include dirt, swarf, metals, and metallic soaps that evade the existing filtration system, are typically reduced to about 2/100ths of 1%.  Process flow rates range from 20 to 36 gallons per minute depending on the level of contaminates and type coolant processed.

Effects of the service on reducing contamination levels are very predictable.  Even in severe situations where tramp oil levels may be high as 10% or solids high as 1%, systems are restored to the excellent condition as described above after a process turnover rate of 3 to 3 1/3 times has been achieved.  Or, when 300 to 330% of the reservoir capacity has been purified through the process.  Typical process times to achieve excellent results for coolant central systems are as follows:

                        10,000-gallon systems:  24  HOURS

                        50,000-gallon systems:  120 HOURS

                        80,000-gallon systems:  180 HOURS

For manufacturing companies taking advantage of side-stream coolant system purification services, the cost for the service is based on the amount of time the coolant service contractor is on site and is billed on an hourly basis.  Depending on the size of the system, level of contamination, and the degree purity required, the cost for the purification service ranges from $0.20 (twenty cents) to $0.45 (forty-five cents) per reservoir gallon.

Purifying a system instead of dumping it will not eliminate the need to occasionally drain a central system to remove accumulated sludge.  Nor will it solve the serious problems that develop when dissolved solids build up to excessive levels.  It has however been a successful tool for numerous coolant central system operators to achieve extended coolant cycles while improving the performance and efficiency of the machining operation.


*Robert A.  Picek is the Proprietor of Lormar Reclamation Service of Norman, Oklahoma.  Since 1985 Lormar has completed thousands of projects nationally and helped numerous manufacturers solve fluid contamination problems with their metalworking coolants and industrial oils.  For detailed descriptions of the type services provided, review Lormar’s web-site at

Lormar Reclamation Service
2845-D Broce Drive, Norman, Oklahoma 73072
Phone: 405-321-0636, E-mail: