I used to swear by flood coolant until a spindle failure changed my mind

So I ran a VMC for about 4 years at a shop outside Phoenix and I was a flood coolant guy, period. Thought mist was for hobbyists and dry cutting was for people who hated their tooling. Then last spring I had a spindle bearing go out on a job with a tight deadline. The teardown showed the coolant had washed grease out of the upper bearing housing, which I never even considered. Apparently the nozzle angle I set was pushing fluid right into the seal area over time. I read a technical bulletin from the machine builder that said flood can actually pull chips into the bearing path if the shield is worn. I switched to a minimal quantity lubricant setup for aluminum and steel roughing, just a tiny air-oil blast. Three months in and my spindle temps run 15 degrees cooler and I use a fraction of the fluid. Has anyone else switched away from flood after a similar scare, or am I overreacting to one bad bearing?

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evan_stone26d ago

Shit, maybe the real issue is nobody ever checks their coolant concentration before it wrecks something else.