Surface treatments for technical springs (part 2)

Surface treatments give technical springs special properties. The possibilities of these processes range from visual refinement and special rust protection to increased resilience, electrical conductivity or robustness against heat. In the second part of our overview, we present further processes that help to customise technical springs even further.

One of the most common processes for the surface treatment of Steel springs is phosphatising. It is also known as Parkerising, bonding or atramentising. The different names have one thing in common: it is a treatment technique that is particularly valued for two effects: Favourable sliding properties and temporary corrosion protection.

A phosphate solution is used to form a conversion layer on the metallic surface through chemical reactions. This consists of firmly adhering metal phosphates and offers the best basic conditions for further applications, for example an optimum bonding agent for paintwork, or where electrical insulation or friction and wear reduction are important. Cost-effective and efficient, it is a widely used process for achieving temporary corrosion protection.

If the surface of a steel spring is passivated, it has a highly resistant oxide layer, can regenerate itself and therefore offers excellent corrosion protection. Passivation creates a protective layer, the passive layer, either naturally through moisture and oxygen or through passivation chemicals. The resulting layer can slow down corrosion to a considerable extent. In order to apply the process, metallically pure surfaces are required. If passivation takes place naturally, it takes a few days. The use of passivation chemicals reduces the treatment to a few minutes.

One of the best-known processes in optical surface treatment is chrome plating. In a multi-layered structure, chrome-plated surfaces offer good corrosion protection and low static friction. Their advantage lies in the fact that they can be mechanically reworked, have a high temperature resistance and do not tarnish. They are also resistant to oxidising media, abrasion-resistant and, last but not least, decorative.

There are many different surface treatment options for technical springs. The specific application ultimately determines which treatment is functional and efficient. Sound advice clarifies this question and - at Schaaf - results in a customised product that also has the desired lasting effect in terms of surface performance.