Most worn Hydraulic Rods or Shafts can be rechromed, instead of being replaced for a fraction of the cost and time of new!
Inspect and Measure the Worn Part
Measuring a worn part with a micrometer to establish the exact amount of wear, and thus how much chrome needs to be added to the part, plus a small amount for grinding down.
Prepare the Surface
Surface preparation to give a ‘clean’ surface for chrome plating is essential and is carried out by first degreasing the worn part, followed by light grinding or shot blasting to remove any corrosion, leaving a surface of consistent roughness. Deep pits or scores must be addressed to ensure that the chrome will fill the area to a uniform thickness, as chrome only plates to what exists on the surface and will not fill a void.
Build Up the Chrome Layer
Hard Chrome Plating is a hard wear resistant coating made from chromium. It is deposited from an electrolytic bath of chromic acid and the process builds up a dense, hard layer on the surface of the part being plated. The process parameters of bath temperature, current density and dwell time are all critical to achieve the required build-up of chrome. Due to the inherent properties of chrome to build up more on edges and sharp corners than other areas of the part, masking and racking are used to try and achieve an even layer. As this process uses hexavalent chromium, the operator must work within the limits set by the HSE for chromium processes in the workplace.
Grind Back to Dimension
The part is then circular ground back to its exact size and surface finish, for example to a tolerance of ±0.01mm and surface finish of Ra 0.2 to 0.4µm for the application of hydraulic and seal components.
Check the Restored Surface
The completed component can then be inspected, dimensional checked, adhesion tested for, and for signs of pitting/edge build-up. A useful reference for Hard Chrome Plating is www.poeton.co.uk/advanced-treatments/apticote-100-hard-chrome.
Hydraulic rams, piston rods, press tooling, dies and other linear components that have a simple wear surface and a fixed dimension, are typical for hard chrome restoration.
