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PTFE Coating vs Hard Chrome Plating

We are having a hard time choosing between Teflon coating and "Hard Chrome" plating of a swing-bolt assembly for an industrial environment. The assembly consists of a 1.25" dia. high tensile bolt threaded into a 3" diameter pin. The pin rotates inside holes which bored in two 1/2" thick steel plates about 4" by 10". We initially thought the assembly should be PTFE coated, since there is good experience in the petrochemical industry with PTFE coating of high tensile (ASTM A193 grade B7) studs & nuts. However, we wonder if Hard Chrome plating of the whole assembly (or just the steel plates)has an advantage (or disadvantage) over PTFE.

Keith Rasmussen
- Burlington, Ontario, Canada
2000

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Depending upon the geometry of the parts, you may not be able to plate nickel and chrome to a sufficient thickness to achieve corrosion protection as well as wear protection you need.

Hard chrome doesn't have much throwing power, so you would need special fixtures/internal anodes to get full coverage (most likely).

You will be unhappy with a coating that will corrode in short period of time, and that assembly sounds like it has too many low current density areas for good coverage.

  
Tom Pullizzi
Falls Township, Pennsylvania
2000

Does the equipment come apart for maintenance? Will it be easy to access? How harsh of environment will it be exposed to? Just a few other question you may need to address in deciding. PTFE for the oil industry has proven itself in all sorts of functions and compared to hard chrome, it is an easier process to repair and re-coat if required.

Craig Gaskin
- surrey, bc, canada
May 18, 2010