Can we talk about coolant concentration meters

I was reading a shop manual from a big tooling company last week and it said most shops run their coolant way too weak. They had a chart showing that even a 2% drop below the right mix can cut tool life by almost 30%. I checked ours with a refractometer and sure enough, we were at 5% when the manual called for 8% for our aluminum work. I had no idea it made that big a difference just from being a little off. Has anyone else checked theirs lately and been surprised?

2 comments

2 Comments

murray.cole1mo ago

So @robert64, what do you figure is a real world drop in tool life you'd actually notice on the floor?

robert641mo ago

Those charts always seem a bit extreme to me. We ran the same semi-synthetic at like 4% for years on general steel work and never saw tools just falling apart. Maybe for super high-speed aluminum finishing it matters, but for everyday jobs? I'm not totally sold. Refractometers need calibration too, and coolant gets dirty. The reading might be off anyway. It feels like one of those things the tool companies push to sell more coolant.