Pro tip: A shop foreman told me my coolant mix was too weak and showed me the math

I was running a job on a VF-2 last month and getting more tool wear than expected. The foreman came over, checked my mix with a refractometer, and said, 'That's at 6%. For this material, you're washing tools, not cooling them.' He pulled out a chart showing optimal ranges for different alloys. I started mixing to 8% for aluminum and 10% for tougher steels. The difference in finish and tool life was clear within a week. What's your go-to ratio for general stainless work?

4 comments

4 Comments

leewalker3mo ago

Guess I should listen to @betty_carter and stop being so cheap with the coolant.

betty_carter3mo ago

I'd run 8% for stainless too, that extra lube makes a real difference.

davidkim3mo ago

Actually coolant percentage depends on the water hardness. Our shop water is soft, so we run 6% for stainless.

roberts.leo1mo ago

Hard water needs more coolant to stop rust, soft water lets you run leaner. We test our mix weekly with a refractometer to keep it dialed in. Have you checked your water hardness lately?