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It is often not necessary to replace a worn shaft. Even if the shaft has worn down by a few tenths of a millimetre, a hard chrome plating can very cost-effectively restore it to its original dimensions and allow it to be finished as required.
Building Up Lost Dimensions
The chrome is electrolytically deposited in layers of controlled thickness, typically in the range 0.025mm to 0.5mm, onto the worn surface. This means that a rod that has worn oval, corroded, etc. can be re-machined to a near perfect blank for finishing.
Hardness and Surface Finish
The chrome coating is typically deposited to a hardness of 850 to 1,000 HV and is therefore much harder than the underlying component. The as-plated surface finish is somewhat rough but this is not a problem as the final surface finish is achieved by grinding the plated part to size.
Grinding Back to Tolerance
Following the hard chrome plating process the part is then removed from the bath and has a slightly rough surface, which needs to be removed to the required surface finish. This is carried out on a cylindrical grinder where the excess chrome is removed to give the part its precise tolerance, usually to a few microns over its complete length.
What Chrome Can and Cannot Fix
Uniform wear, corrosion pitting to moderate depth, scoring on hydraulic rods, pistons and shafts – all are repaired to high standards using chrome. However, cracks of any size, fatigue damage and, more importantly, excessive material loss (over about 0.5mm) will generally require some form of pre-treatment before chrome can be used successfully to extend the life of a worn part.
Realistic Service Life Gains
Poeton Hard Chrome restoration of hydraulic rods and shafts to original dimensions are returned to service, achieving the same or even longer wear life than the original part. If you want Chrome Plating, //www.poeton.co.uk/advanced-treatments/apticote-100-hard-chrome-plating/ is a good place to start. Hexavalent chromium plating processes are strictly controlled and the operators must work within the relevant workplace exposure limits.
Rebuilt to original specifications, worn parts perform as new. The ultimate solution for the engineer.
