Quantifying the effects of grease on friction factors
Quantifying the effects of grease on friction factors
(OP)
I am a recent graduate, and while I do have internship experience performing structural analysis I am rather new to the industry. My problem is that I have a joint connecting two cylinders and need to find the friction between the two surfaces to perform the analysis. I know the two materials and have found the friction between them. Yet the joint has grease applied to each mating surface and I am having trouble estimating the effects this grease has on friction.
Any standards or analysis that would get me moving in the right direction would be greatly appreciated.
Regards
Any standards or analysis that would get me moving in the right direction would be greatly appreciated.
Regards





RE: Quantifying the effects of grease on friction factors
Gravity and a tilting table are all you need.
RE: Quantifying the effects of grease on friction factors
Friction is one of engineering analysis' dirty little secrets. Oftentimes you'll get away with using the worst case book value. One day you'll do that and make an expensive (or dangerous) mistake. So, you end up measuring it.
Most recently I can think of a 2 million dollar recall that was due to a friction estimate that was incorrect.
If it is impractical to measure it run the analysis at 0.1, 0.3 and 1 . Take the worst of those three. Be aware that those are not the bounds of frictional behaviour, but you are dead unlucky to go outside them with steel, oil, water wood and crude plain bearings. Obviously designed bearings, or anything involving water and ice, or air, can be much less, and anything involving rubber can go much higher.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Quantifying the effects of grease on friction factors
RE: Quantifying the effects of grease on friction factors
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Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Quantifying the effects of grease on friction factors
Thank you.
RE: Quantifying the effects of grease on friction factors