Desirable hardness differential

[Tricky070]

I have a pin (300mm diameter) running in a bush 25mm thick.
rate of rotation is around 10rpm. Load is around 300-400 tonne. Yes heavy. The wear rate is currently an issue, pin is around 600HB. Question is what is the optimal hardness of the bush?.
At the moment i favor a hardness differential of 10-15%. But i lack any trial data to back this up.

 

[alexit]

Is bushing easy replace or pin? I would bias the difference towards the easy to service part. We try to keep load bearing surfaces >45 HRc with (our case) bushing being >55 HRc.

 

[Tmoose]

How wide is that bushing, and is the pin stout enough to prevent edge loading? Is the bushing housing so stiff it forces edge loading?

I think hardness is the last thing I'd look at. Once the geometry is optimized or at least improved, Material choices can easily make 10 X difference in wear rates. Dissimilar is almost always best. Even After material is optimized, Lubrication beats hardness at least 10X.

 

[Tricky070]

There are 5 bushes 10" wide. 3 on one part and 2 on the other with the pin joining them like a hinge. The articulation is about 110°. Is constantly working 24/7.

 

[Tricky070]

In in open cut mining equipmet, am working on lube system trials at the moment but they keep failing after a short amont of time. (As joint is to earth engageing equiment )

 

[MOB1]

Pins in open cut mining machines often run in austenitic manganese steel bushes (cast) where lubrication is often marginal or non existent.
The different steel structures (martensite vs austenite) and the excellent work hardening characteristics (of the bush) often serve to make the comnbination of hardened steel against manganese steel work well.

 

[unclesyd]

You have asked the proverbial 64 dollar question as this has come up in every bearing seminar that I've attended and the answer was nearly always the same, it depends.

Here is a bearing that I've seen used in similar situations with good success. There used to be more information on the site but it still may be available as a booklet if you contact them. Like everything else they were gobbled up.

http://www.ermcompp.com/where-use-maxam.htm