Metal finishing Q&As since 1989

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Rebuild of axle shaft bearing seats

 

Occasionally the matter of recovering a worn axle shaft at the bearing seats comes up, and one of the alternatives is to build back the diameter using Hard Chrome. What are the practical (coating thickness) limits for building a shaft back to spec. I was reading some of the articles on your web page and haven't seen anything on the description of what the HVOF process is or what "HVOF" stands for. Further, no explanation or comparisons are given on what the significant differences are between Hard Chrome - HVOF - HEEF - and Electroless Nickel?

Thanks in advance for help to answer these questions.

Joseph Poradzisz
- Monee, IL., USA

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Hi,

HVOF stands for Hyper Velocity Oxygen Fuel and it is a thermospray method that projects powder particles to the surface at very high temp and speed. It works better with carbides and other hard particles. The adhesion is fair to good but only mechanical, the surface has to be roughened by turning or shot blasting, the buildup proceeds mostly on line of sight and it always require post machining (not well suited for ID's). Hard chromium, electrolytic or electroless nickel are plating processes that produce metallic bonds to steel, normally they also have to be post machined or ground. There is another alternative called brush or selective plating. This process can be done in house and most of the time no post machining is necessary.

Guillermo Marrufo
Monterrey, NL, Mexico