Initial situation

In hydraulic engineering, hard-chromed hydraulic cylinders frequently suffer corrosion and wear. And over time, the surface texture and roughness of the piston rods change. The consequences are often surface smoothing and hence an increase in friction on the piston rod seals coupled with a higher risk of failure. In addition, microcracks may appear as soon as chromium coatings are applied, which can also lead to corrosion-related failure. Furthermore, the chrome tips on the piston rod surface are usually worn away quickly. All this has a negative impact on the entire tribological system and may lead to the failure of hydraulic units. Therefore, our clients are looking for surface coatings which are more resistant and durable, and whose surface properties are more stress-resilient, hence helping to enhance the tribological system.

The solution

The HVAF coating process enables dense, hard, highly corrosion-resistant carbide surfaces to be produced. Much higher surface hardness (with adjustable Ra values significantly below 0.1) can be achieved in comparison to hard chrome and alternative HVOF processes. The highly stable topography makes for stable system conditions and significantly less stress for sealing elements. As a result, the coatings make excellent mating surfaces for seals such as radial shaft seals and sealing glands. Low-oxide, non-porous coatings with excellent adhesion produced using HVAF increase components’ corrosion resistance and lead to longer lifetimes.

The coating systems used by Putzier are hard metal coatings based on chromium or tungsten carbide using the HVAF coating process. For this purpose we employ products such as MC32, MC34 and MC40.

The result

This method optimizes the sealing system by creating a coating with a homogeneous, crack-free and highly polishable surface which is ideal for use in tribological systems. Higher coating hardness with a dense microstructure enables surfaces with a longer lifetime and reduces the formation of grooves in piston surfaces. Low-oxide, low-porous coatings minimize corrosive attack and enable a longer lifetime in highly corrosive environments such as a highly saline marine atmosphere.

What can we do for you?

Clients benefit from powerful coating systems based on technically superior methods such as the HVAF coating process to give them the edge over their competitors. Focus on market trends and regular participation in national and international research projects ensure we are fully prepared for future challenges.