Why metalworking fluid concentration is important

Skin disease and lung disease can occur in workshop machine operators, either because their skin is regularly in contact with metalworking fluid (MWF), or because they inhale MWF mist.

Risks to health increase as the composition of the MWF deteriorates in-use, becoming contaminated by tramp oil, soluble metals, metal fines, and microorganisms.

MWF concentration is, therefore, very important.

During use MWF may increase in concentration and foam due to evaporative loss of water. There may be an increased risk of misting.

Diluting MWF below recommended concentrations may increase the risk of bacterial contamination and corrosion, resulting in poor cutting performance, shorter sump life and increased cost.

Operating MWF at a temperature above 30 °C creates optimal conditions for microbial growth and increases MWF concentration through evaporation.

Always use the correct MWF concentration recommended by the supplier.

Adjust MWF concentration using a higher or weaker strength pre-mixed MWF. In most circumstances it is advisable not to use water or the concentrate stock directly.

Metalworking fluid quality checks for concentration should be done weekly. If results are outside the recommended level, you should take corrective action.

Watch this short video from UKLA about using a refractometer to check concentration levels.

Source: UKLA-HSE-Good-Practice-Guide-for-Safe-Handling-and-Disposal-of-Metalworking-Fluids.pdf