Bearing running temperature
Bearing running temperature
(OP)
Hello bearing lovers,
I'd like to discuss another phenomena with all of you. I think we all know that running precision bearing too high in temperature is not good (over 50 C) but what about them too cold. For angular contact bearing, if your bearings run too cold, it could mean that there is not enough preload. But what if the run-in final temp is ok let say 35 C (95F). I put that spindle on the field where the ambiant temp. is about 8 C. The spindle ran 4 hours loaded at 3600 RPM. The final temp. is 16 C (60 F) which is really too low to me. But since the temp. is the same on both end of the spindle and they have the same bearing and the temp is about the same for all the spindles on that machine, I can't say it's a preload issue or whatever could come from the spindle. I'd say it's because of the ambiant temp. (8 C) and the spindle's casing which is really thick. So this casing is cold down during the weekend and when they fire the spindle back up, it can't warm up enough because the casing dissipates too much heat. I'd like too know if anyone have ever had this kind of operation at low temp. and what are the consequences?
I'd like to discuss another phenomena with all of you. I think we all know that running precision bearing too high in temperature is not good (over 50 C) but what about them too cold. For angular contact bearing, if your bearings run too cold, it could mean that there is not enough preload. But what if the run-in final temp is ok let say 35 C (95F). I put that spindle on the field where the ambiant temp. is about 8 C. The spindle ran 4 hours loaded at 3600 RPM. The final temp. is 16 C (60 F) which is really too low to me. But since the temp. is the same on both end of the spindle and they have the same bearing and the temp is about the same for all the spindles on that machine, I can't say it's a preload issue or whatever could come from the spindle. I'd say it's because of the ambiant temp. (8 C) and the spindle's casing which is really thick. So this casing is cold down during the weekend and when they fire the spindle back up, it can't warm up enough because the casing dissipates too much heat. I'd like too know if anyone have ever had this kind of operation at low temp. and what are the consequences?





RE: Bearing running temperature
RE: Bearing running temperature
RE: Bearing running temperature
If you give the bearing manufacturer's tech dept your running temperatures and shaft and housing fits they can calculate the operating preload, and the spacer offsets necessary to make it right.
A rapid temperature rise in a given time can be a powerful indicator of impending runaway bearing preload. I'd limit that rather than a temperature limit. Gotta get close to that outer race.
I'd be making some kind of vibration measurement on the housing during warm up. Good old Spike Energy (IRD trade name) is pretty good at detecting the squeaky scratchy scream of bearings being squeezed to death and dragged through their oil film. Most other analyzers have functionally similar features.
RE: Bearing running temperature
RE: Bearing running temperature
On the bench test
Side Outer ring temp Housing temp
Fix 102F 95F
Free 100F 94F
The housing temp I recorded on site was :
After the week-end before starting the machine : 46.4 F
After 4 hours loaded : 60 F
So I can say I have around 40F difference between outer ring temp and onsite housing temp. But another way to see that is that because the housing dissipates a lot of heat, the outer ring on site temp. is maybe lower (around 65F). My grease has no problem running at that temp but my tolerances are not designed for that. Could it be problematic? I'll have a call to the manufacturer and let you know what I got.