This article was updated on January 14, 2024.
Most machinists would agree that a properly mixed, high-quality cutting fluid smells quite pleasant. But if it isn’t maintained or cleaned, cutting fluid can start to stink.
Give it a couple of weeks of neglect and the Monday morning stench is enough to make even the most olfactory-challenged machinist yearn for the weekend. If the assault on your nose isn’t bad enough, however, rancid coolant is hard on other things too—from your health to tool and machine life, finishes and a host of key metalworking processes and parts.
Here are a few pointers on optimizing coolant maintenance, which can buoy productivity while helping to protect your shop’s most important assets: its workers.
Is CNC’ Coolant Bad for Your Skin?
To be fair, even freshly mixed cutting fluids contain a host of chemical additives such as biocides, emulsifiers, corrosion inhibitors and anti-foaming agents that may cause skin irritation, rashes and dermatitis. When cutting fluid gets dirty or is improperly maintained, however, health risks increase significantly.
When cutting fluid is neglected, the concentration of these chemicals may reach unsafe conditions. Also, an improperly maintained machine tool sump becomes a perfect breeding ground for microbes.
“At low concentrations, bacteria can grow unimpeded in the sump and cause pH of the coolant to drop and cause rust,” says John Treese, director of global training at Master Fluid Solutions. “Low concentration [of fluid] can grow bacteria that can aggravate skin issues including simple cuts and scratches. High concentration adds too much chemical that can do the same.”