Just realized my coolant mix was off after a weird finish on a batch of 6061 parts

I was running a job for 50 aluminum brackets at the shop in Springfield last Thursday. The surface finish on part 15 started looking hazy and rough, almost like it was galling. I checked the tool, feeds, and speeds first, but everything was set right. Then I dipped a refractometer in the sump and saw the concentration was way low, like 3%. I'd topped off the tank with straight water earlier by mistake. I shut it down, mixed in the proper coolant, and ran the rest of the batch fine after cleaning the machine. Has anyone else caught a coolant issue by the finish before the tool actually failed?

2 comments

2 Comments

the_emery1d ago

My buddy had a similar thing happen with his lathe. He was turning some stainless and the parts started coming out with these weird rainbow streaks, like heat tint but cold. Took him three pieces to realize his coolant pump line had a small crack and was barely spraying. The finish was the only clue before his insert chipped.

willow_garcia1d ago

Wait, you ran it all the way to part 15 before you checked? I mean, that haze would have had me spooked after like part two. I guess it's good you caught it before a crash, but idk how you let it go that long. That's a lot of scrap risk.