You don’t want a worn rod to be devouring your new cylinder seals in a few months. Look at a few examples of “before restoration” rods before returning your cylinder to service.
Get The Surface Finish Right
A polished surface may appear to be good but it will wear dry and in most cases cannot hold sufficient lubricant. Most hydraulic rods require an Ra surface finish of 0.1 to 0.2 microns and it is advisable to check how the supplier measures and specifies surface roughness.
Match Thickness To The Job
A short-stroke ram that is lightly loaded may only require a 20 to 30 micron plating, whilst a long-stroke rod that is subjected to arduous duty in dirty operating conditions, may require a thicker coating of a harder chrome material. The plating thickness should be specified in relation to the actual diameter of the rod and the stroke length.
Check For Porosity And Micro-Cracking
Porosity, excessive micro-cracking or even corrosion can easily penetrate through even the finest of cracks. Once corrosion has penetrated the surface of the plate it will develop into pitting and in time form fatigue cracks. This will lead to the plating failing prematurely. Rods should be inspected prior to use for any signs of surface deterioration. More on Hard Chrome Plating can be found at https://www.poeton.co.uk/advanced-treatments/apticote-100-hard-chrome/.
Match Base Steel To The Duty Cycle
Do not mistake the chrome plating with the base steel. In most cases the plating can be as weak as the base material. Most hydraulic cylinders are made from medium tensile steel with varying hardness. The base steel must have sufficient hardness and tensile strength to withstand the normal duty cycle of the rod. Several re-plating can reduce the surface hardness and lead to premature failure.
Protect Plated Rods In Storage
Protect the plated rod in storage by covering the ends of the rods with end caps, wrapping the rods in VCI paper or VCI film and storing them separated from each other to prevent contact with other bare metal surfaces.
Know When To Strip And Re-Plate
Surface damage to the chrome such as scoring, dulling and minor pitting may be able to be polished out but will normally need to be fully stripped and re-plated if it is severe such as flaking or deep scoring, or if the rod has become appreciably worn and is no longer round. It’s rarely cost effective to try to repair worn hydraulic rods with polish.
Getting the above 6 points right will give you years of service from the hard chrome plated rod, before it needs any further work.