“Piston rod” – as a shaft in a heavy-duty plain bearing system?

Michael Hornung | 23. April 2020

As the name suggests, the original purpose of this material is to be used as a machine element in piston engines.

I especially associate “piston rods” with their use in hydraulic cylinders and have a hard chrome shaft in mind. Generally, this is not a valid statement. For various reasons, nitride shafts are now also used as piston rods in hydraulic cylinders …

But in the following we will talk about these hard chrome shafts.

Piston rods – long proven in linear applications!

In fact, the application in the hydraulic cylinder is also similar to a kind of bearing. The piston rod (hard chrome shaft) slides in a straight line through a bearing and a seal.

But what does this look like in a heavy-duty pivoting application?

In order to assess the possible use of piston rods in heavy-duty applications, igus has carried out numerous tests in its own test laboratory.

Wear results of iglidur G plain bearings on different shafts

The experiment was conducted with part GSM-2023-20. To achieve a surface pressure of 45MPa, which is usual for agricultural engineering and construction machinery, a force of 18,000N is applied.

In combination with iglidur G, “soft” free cutting steel is clearly at a disadvantage in this heavy load test. The result with the harder Cf53 is significantly better (wear rate 65µ/km) and can be considered good. If this very material is hard chrome, wear is reduced by a factor of about 3.4 to 19µ/km.

From the point of view of optimising the service life of a plain bearing system, the use of hard chrome surfaces can be rated as positive. Additional advantages of piston rods are the good availability, the costs and above all the high corrosion resistance.

Further results on other material combinations and application parameters are available from igus.