Mill coolant system design
Soluble Contaminants. Soluble contaminants, if problematic to the coolant solution, must be removed before they enter the system, because they will become a part of the circulating coolant solution and may become concentrated in the solution. Primary sources of soluble contaminants include diluting water, coil coatings, rust preventives applied inline, and cutoff oils.
Coil coatings, rust preventives, and cutoff oil can be reduced systematically, chemically treated out of the system, or eliminated with proper application and containment equipment (or by using compatible chemistries).
Diluting water, however, contributes significantly to buildup of soluble contaminants that cannot be removed. Water is the most abundant compound in coolant solutions and therefore is the greatest potential contaminant. It typically is used as-is from the tap and contains a variety of inorganic and organic salts along with biomass such as bacteria and fungi. These contaminants become concentrated with use and quickly deteriorate most coolant solutions.
Purification is completed using carbon filters to remove soluble organics, inline ultraviolet light for bioactivity, and reverse osmosis deionization to remove soluble salts. Water quality requirements for a given coolant are based on coolant formulation, tube quality expectations, and incoming water quality versus purification costs.
