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479 views
09:26 Apr-14-2008

Eric Chen

Engineering,
GE Aviation,
China,
Joined Nov 2002
7
MT for bearing hardening surface

In the past PT was carried out for the hardening surface of bearing. Now some company change to MT with AC yoke. My question is where is the hardening crack starts from? The interface between the harden layer and the parent material or the hardening crack starts from the bearing surface? If the hardening crack starts from the interface between the parent material and hardening layer, DC would be better than AC.

Can some one explain to me?

Thanks!



    
 
03:10 Apr-21-2008

Godfrey Hands

Engineering,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
286
Re: MT for bearing hardening surface ----------- Start Original Message -----------
: In the past PT was carried out for the hardening surface of bearing. Now some company change to MT with AC yoke. My question is where is the hardening crack starts from? The interface between the harden layer and the parent material or the hardening crack starts from the bearing surface? If the hardening crack starts from the interface between the parent material and hardening layer, DC would be better than AC.
: Can some one explain to me?
: Thanks!
------------ End Original Message ------------
For production of bearing parts, the surface is probably the most critical surface, but when the bearings have been in service, failure is most likely to originate at the "Hertzian zone", which is just underneath the raceway ( microns to millimetres depending on bearing size, geometry etc). MT with DC should be considered here, but make sure that you can adequately demagnetize the part, else the residual magnetism will attract ferrous particles which can quickly destroy a bearing.

Godfrey




    
 


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