That Tuesday the spindle screamed and I lost a full day's work

Middle of a run on some 304 stainless, maybe 30 parts in, and the spindle starts making this nasty grinding noise. Thought it was just normal chatter at first. Kept going for another 10 minutes until it seized up completely. Took the rest of the day to pull the spindle, find the bearing was shot, and wait for the supplier to drop off a replacement. That was 8 hours of downtime plus the scrap from the last 5 parts. Has anyone else had a bearing fail without any warning signs beforehand?

2 comments

2 Comments

miles27912d ago

Did you check if the coolant concentration was off before the failure? I've seen three bearing jobs now where the coolant got too watery and basically stopped lubricating the spindle bearings enough. The chip loads went up and the heat cooked the grease out. The guys running those jobs swore they couldnt hear anything different until it was too late. Maybe pull a sample next time before you run stainless, just to rule it out.

grantf7312d ago

Wait, wait, wait. You're telling me the coolant got so watery it just stopped lubricating? I didn't know coolant could do that, I thought it was pretty much just for cooling and chip evacuation (and rust prevention, obviously). That's wild. Three bearing jobs, all the same story? So the grease just cooked right out of the bearings because the coolant wasn't thick enough to carry the heat away from the cut? Man, that explains a lot about some weird spindle noise I heard last year, I just figured it was a bad bearing from the factory. I'm definitely pulling a refractometer reading before I run any stainless again.