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Metal chain resists corrosion

Edited by the Engineeringtalk editorial team Oct 23, 2007

Tsubaki NEP chain uses a combination of three layers of surface coating, with a highly resistant base layer that bonds a harder wear-resistant coating onto the chain bushes.

Tsubaki NEP roller chain employs a metal coating process that allows a carbon steel chain to be used in wet conditions without corroding.

The multi-layer metal coating process is modified for different components of the chain, balancing corrosion protection with wear resistance.

Manufacturing processes and component materials comply with RoHS guidelines on restricting the use of hazardous substances such as chromium, materials that have until now been an essential component of all high-strength corrosion resistant chain.

Most 'wet' applications for drive chains involve some exposure to atmospheric moisture and/or intermittent exposure to water-based solutions.

Completely waterproof chain is not suitable for these applications as it is generally manufactured using a combination of stainless steel or engineered plastics, the drawback of these materials is that they are not as strong as carbon steel chain and have to be oversized for high-load applications.

Pure stainless steel chain also doesn't perform well without immersive lubrication.

A corrosion-resistant chain based on carbon steel chain is therefore a far more desirable solution as it can operate with standard power transmission components and sizing calculations.

Various coating methods have been used to protect the surface of carbon steel chain from corrosion when used in an environment where moisture is present.

The problem with this in the past has been that some surface coatings are extremely hard and tend to peel off due to surface pressure exerted by drive sprockets.

Galvanisation is softer and wears away quickly as the chain articulates, thus leaving critical components open to corrosion.

Tsubaki NEP chain however uses a combination of three layers of surface coating, with a highly resistant base layer that bonds a harder wear-resistant coating onto the chain bushes where they come into contact with sprocket teeth.

An additional tough external coating is then used to cover and seal all the other component surfaces with further corrosion protection.

In a salt water immersion test the chain survived over 300 hours immersion without any sign of corrosion.

A standard carbon steel chain would corrode to the point of being useless within 24 hours.

Samples that have been tested up 1500 hours have shown only slight surface discolouration in what is one of the most destructive corrosion resistance test environments for ferrous engineering steels.

The chain is a far less expensive alternative to oversize than stainless steel chains in most situations.

It also has a reduced impact on the environment through lower emissions during manufacture and the selection of less damaging materials in its construction.

Previous corrosion-resistant chains relied on the use of chromium derivatives such as hexavalent chromium and trivalent chromium as water-resistant coatings.

NEP chain complies with current RoHS guidelines on reducing the use of hazardous materials.

It is compatible with standard sprocket dimensions and is available from stock in RF06B - RS24B simplex (seven sizes) and RF06B - RS20B-2 duplex (six sizes).