Impact of Environmental Contaminants on Machining Properties of Metalworking Fluids

In the mid-2000s, metal products manufacturing costs were increasing. With the discovery that metalworking fluids cost about 12% of the machining costs, many manufacturers have begun recycling their metalworking fluids back into their processes. Recycling has the added bonus of reducing the environmental burden on manufacturers who dispose of less fluid.

But how do contaminants impact the productivity of metalworking fluids? ISTC’s Kishore Rajagopalan and his colleague explored this question for tramp oils, salts, and other contaminants. They found that metalworking fluids had no losses in cooling and lubricating functionality until calcium built up so high that the ions caused the emulsion to destabilize. Metal surface roughness showed no difference between fresh and contaminated metalworking fluids. However, the corrosion inhibitor was affected due to the various fluid formulations interacting differently with the contaminant chloride.