Third shift coolant smell made me flip on flood coolants

Used to run everything dry, thought coolant was just a mess to deal with. Last week a 3/8 endmill in 6061 started squealing so bad my foreman Dave said "trust me, flood it or watch that part scrap," and the finish came out like glass. Has anyone else fought the coolant switch and then realized the machine runs quieter for it?

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elliot4518d ago

The real thing nobody talks about is the thermal shock on the insert or endmill when you flip the coolant on mid-cut after running dry. That 3/8 tool was probably at 300 degrees or more in the cut zone, and the sudden liquid hit can micro-crack the carbide edge before it even gets a chance to cool evenly. I've seen it happen on a lathe with a boring bar, tool lasted maybe ten minutes after the switch before the corner let go. Running flood from the start lets the tool sit at a steady temp the whole time, so you avoid that whole mess. Plus the chips don't weld themselves to the flutes when they cool too fast, which is what causes that squeal in the first place. You might have gotten lucky with your part, but I'd never recommend doing the switch on a live cut again.