Water Quality Affects Coolant Performance

Water Quality Affects Coolant Performance

Decreased grinding fluid performance? Excessive corrosion?Maybe it’s time your water quality was evaluated.

Coolants contain ~90% water, with the remainder containing additives to prevent from corrosion, foaming, and bacterial growth. However, while the quality of these additives is precisely controlled by the coolant manufacturers, the water quality varies depending on its source. Therefore, your water quality should be monitored before diluting the concentrated coolant.

Factors that affect water quality are water hardness, pH, and the presence of chlorides, sulfates, and lead. Monitoring the pH level can identify bacterial growth. Generally speaking, hard water is the amount of calcium and magnesium salts, expressed in milligrams of calcium carbonate per liter of water (ppm). A pH of 7 is defined as natural. Water below pH 7 is acidic, above pH 7 is basic. Most commercially available coolants are basic in their concentrated form with pH levels between 9 and 12.

For example, the ideal hardness levels for glass working coolant are between 80 to 110 ppm. Water with hardness value below 70 ppm is considered soft and may result in foaming whereas hardness value that exceeds 200 ppm is consider hard and may result in separate oil from water.

Hard water contains sodium and potassium salts, which can cause machine and work-piece corrosion. It can also cause significant discoloration on the surface of steel and aluminum parts. Besides, hard water is difficult mixed with coolant, so it easily separate oil and water, and part of the concentrated liquid is consumed to soften the water, and cannot function as a cutting fluid. In order to ensure the performance of cutting fluids, adding more concentrated fluids increased the cost.

■ Very soft:0 - 49
■ Soft:50 - 124
■ Medium:125-249
■ Hard:250-369
■ Very hard:370 and above

▼ Recommended standards for water hardness of cutting fluid
Recommended water hardness is between 50ppm. And it resulting in poor cleaning performance. It is recommended to consult relevant professionals for on-site inspection and analysis.

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