How Many Times Can a Component Be Repaired by Hardsurfacing?

Hi!
We sucessively repaired hot leveller rollers several times along the years using hardsurfacing processes.
However, the useful life of these components dramatically fall after the lattest repairs. This fact arised some doubts if this can be blamed to the repairing process or if the component is no more able to be repaired after being sucessively submitted to hardsurfacing processes.
Is there some way to verify when a component no longer can be re-repaired by a hardsurfacing process?
Thank you very much for your attention!
All the best,
Antonio Augusto Gorni COSIPA Steelworks agorni **at** iron.com.br

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When an ultrasonic inspection reveals flaws that make it uneconomic to repair. Anything can be fixed, it just might not be cost effective to do it properly. Shafts usually have to be a large size before it pays to rebuild used ones.
With a lot of shaft reclaimation/ roller repairs, the part has been machined to remove all traces of previous hardsurfacing treatments. Any other flaws are excavated and filled with matching material.
Then, the part is built up using a softer material, just to the point where you want the hard surfacing to begin. _Then_ you add the hardsurfacing. A lot (not all) of hardsufacing treatments are limited to about 2 layers of thickness, before they begin "relief checking". It's really cracking, but the electrode manufacturers don't call it that.
If you have hardsurfacing more than 3 layers deep, it may explain why you are having problems. A lot will depend on the type of hardsurfacing used.
Wayne posted and emailed
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One guideline that I've used is the intricacy of the part, the more intricate the part, the greater the cost to replace with new and the more likely to be a candidate for rebuild. Shafts with a number of steps in diameter, keyways, and/or splines fall into this category. Mr. Bengtsson is correct about removing flawed material and old hard-surfacing.
Jerry
Wayne Bengtsson wrote:
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