Coating on bearing seating area

[raviswanadha]

Hi All,
i have to spray a bearing seating area of a shaft of 460mm diameter and 360mm length of bearing seating.The Shaft is stationary and inner race of the bearing is shrink fitted on the od of the shaft. The bearing will be heated up to 150 deg temp. The outer race with bearing race will rotate with hub assembly .65 bar pressure shall be applied on the shaft to pull down for grinding pressure. Vibration will be there in the entire assembly as it is working in a grinding mill .
Please consider the above and give a suitable recommendation.
Best Regards
Ravi

[Simon Kim]

Hello Ravi,

I would like to recommend applying Ni hard facing alloy or Liquidmetal Amarcor M Wire by arc welding.

Because torsion stress is affect to deep depth on the rotation shaft.
So just thin spray is not good for endurance limit.
In case of just rotation stress, that will be affect to thin depth layer.
However rotating shaft is placed at high friction and sliding stress.
So the shaft surface has high torsion stress under the high frictional heat.

Ni hard facing alloy has good properties at high temperature.
And it could be make thick layer.
Armacor M has low frictional coefficient.
http://www.armacor.com/armacor/about/

Furthermore please consider both of the hardness and the friction coefficient with boss material.

With wishing your successful result,

Simon

[Gordon]

Hi Ravi

No disrespect to Simon Kim's recommendation as I think the coatings will be fine, just not so sure on the reasoning behind the recommendation.

As I see it, the coating function is to support the bearing and more as a dimension restoration coating. The shaft, coating and inner bearing race are essentially stationary I assume from your description. The coating should then not have any intended motion, so wear resistance, hardness, friction properties should not necessarily be high priority. I would go for a coating with high toughness that resists fretting. The old Metco 447 NiMoAl composite coating comes to mind (plasma/flame spray) but really many coatings should be capable.

What equipment and materials do you have available for the job?

[raviswanadha]

(09-28-2011 03:54 AM)Gordon Wrote:  Hi Ravi

No disrespect to Simon Kim's recommendation as I think the coatings will be fine, just not so sure on the reasoning behind the recommendation.

As I see it, the coating function is to support the bearing and more as a dimension restoration coating. The shaft, coating and inner bearing race are essentially stationary I assume from your description. The coating should then not have any intended motion, so wear resistance, hardness, friction properties should not necessarily be high priority. I would go for a coating with high toughness that resists fretting. The old Metco 447 NiMoAl composite coating comes to mind (plasma/flame spray) but really many coatings should be capable.

What equipment and materials do you have available for the job?

Thank you guys on your suggestions. Will HVOF coating work in this instance? also the customer is not willing to weld as the shaft may be stressed.

[djewell]

I would suggest something simple and cheap for restoring a bearing journal. 420 SS comes to mind.