Why you should check coolant concentration every day
Run it too lean and you get rust and bacteria. Run it too rich and you get foam and skin problems. Why concentration drifts, and how to keep it steady.
Concentration drives both quality and cost
Water-miscible coolant is diluted from concentrate. The right concentration depends on the product and the operation, so the fluid supplier’s recommendation is always the starting point. The challenge is that concentration keeps changing while the fluid is in use.
- Too lean: lubricity and corrosion protection drop, tool wear and rust increase, and bacteria grow more easily, so the fluid goes rancid sooner.
- Too rich: more foam, a higher risk of skin irritation for operators, and more concentrate used than necessary.
Why concentration drifts
Machining heat evaporates water, so concentration rises. On the other hand, if you top up only with water to replace what leaves on chips and parts, concentration falls. And when operators mix concentrate and water by eye, every top-up comes out different.
How to keep it steady
Measure concentration with a refractometer and multiply the reading by the correction factor your fluid supplier gives you. Log the readings by date so you can see the trend.
- Top up with premix at the target concentration, not with plain water.
- Measure and top up at the same time of day, following the same routine.
- With many machines, an automatic mixing and supply unit is the surest way to take manual mixing out of the process.