Don't Overlook Tank Cleanout

When recharging metalworking fluids, a thorough tank cleanout should be performed so contaminants in the tank don't deteriorate the fresh fluid. Here is a ten-step procedure for doing so.


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Sometimes the obvious is overlooked. That can be the case for metalworking fluids, notes Raymond M. Dick, manager for the Cimcool Technical Service division of Milacron Inc. (Cincinnati, Ohio). Clean metalworking fluids perform better and last longer that dirty fluids. Unfortunately, thorough tank cleanout—a vital step in the process of recharging the tank on an individual machine or central system—is often neglected.

A tank filled with contaminants such as metal swarf, oil, mold growth and pockets of bacteria will cause deterioration of the fresh fluid. Removing these impurities with a thorough cleanout procedure ensures that the fresh fluid can perform at peak performance levels.

Here is a ten-step procedure that Mr. Dick recommends, in cases where complete tank drainage is possible.

  1. Drain the entire tank or central system.
  2. Remove debris from sumps, return trenches, oil pans and filtration units.
  3. Fill the system with water (warm water is best) sufficient to circulate through all lines and machines.
  4. Add a cleaner such as Cimclean 30 (one part cleaner to 50 parts water concentration) and circulate for 2 to 8 hours. While the cleaner is circulating, brush all trenches and filter elements, and scrub machines and oil pans.
  5. Steam clean areas where swarf and/or oil may not have been removed by the cleaner.
  6. Drain the cleaner after cleaner circulation is completed.
  7. Refill the system with enough water to circulate through to remove any remaining cleaner or swarf. If the rinse water is extremely dirty, rinse a second time. All lines and sumps should be drained at this time.
  8. Charge the system with the required amount of water.
  9. Add fresh metalworking fluid to the recommended concentration.
  10. Circulate the metalworking fluid to ensure it is properly mixed before starting production. For precision grinding systems, continue circulation until the fresh fluid reaches room temperature.
When a complete system drain is not possible, Mr. Dick recommends incorporating as many of these cleanout procedures as possible.