Corrosion Resistant Leaf Chain

When materials handling equipment such as forklifts or telehandlers are operating in outdoor environments or where they are being repeatedly cleaned to meet hygiene standards, there is a significant risk of shortened lifespan and failure from rust and corrosion.   

The first step to prevent rust and corrosion taking hold on a leaf chain is to use a suitable lubricant that stays in place. There is a temptation to apply large quantities of lubricant to prevent rust but the leaf chain and its component parts can be subject to a significant amount of contamination from dust, sand or grit even in many seemingly clean industrial environments. Regular cleaning and re-lubricating can be time-consuming and costly but ultimately lead to extended chain life. The best option is to use a corrosion resistant version of leaf chain.

As it is virtually impossible to compare leaf chain performance in industrial environments over long periods, we use a comparative test which allows for consistent comparisons.  For corrosion resistance leaf chain we quickly corroded them in a salt spray cabinet, and recorded the time until white rust (zinc corrosion) or red rust (base metal corrosion) develops.  This timeframe is an indication of the relative corrosion resistance of a material or the protective layer that has been applied. This test is called a salt spray test. Standards for this test are EN ISO 9227 and ASTM B117.

The table below is for comparison only and results will vary dependant on thickness and the shape of parts tested.

Stainless steel and zinc plated leaf chain

Options for making leaf chain more corrosion resistant could include manufacturing zinc plated or stainless steel leaf chain. With zinc plated leaf chain there is a significant risk of Hydrogen Embrittlement which is the process by which high-strength steels become brittle and fracture following exposure to hydrogen. It is generally the result of the introduction of hydrogen during the plating process. With stainless steel leaf chain the working load could be only 1/8^th standard leaf chain, even using high grade precipitation hardened stainless steel the working load could still be only ¼ of the equivalent dimension leaf chain. Replacing an existing chain with a stainless steel chain would require using a significantly larger size leaf chain. We would therefore not recommend using stainless steel or zinc plated leaf chain.

Zinc flake coated leaf chain  

In 1982 we produced one of the first versions of zinc flake coated leaf chain which consistently achieved more than 500 hours in a salt spray test and over the years we have continued to develop the process to achieve the optimum corrosion resistant leaf chain.

2012 saw us moving to a water-based zinc flake coating which was free from Hexavalent chromium which complies with the Vehicle End-of-Life Directive and RoHS Directive On Electrical And Electronic Equipment that prohibit the uses of Hexavalent chromium. This greatly reduced the risk of environmental contamination and created a significantly better working environment for the manufacturing staff.

In 2016 we further improved the process so individual links are coated before assembly. This ensures an even coating coverage and thickness on the leaf chain plates and consistently achieved more than 800 hours in a salt spray test.

Key features of zinc flake coated leaf chain  

• No reduction in tensile strength – the steel types used in leaf chain components have their mechanical properties altered through heat treatment. The lower temperature of our coating process means that the tensile strength of the chain remains the same as our standard leaf chain which is at least 20% higher than required in ISO standard.
• Up to 800 corrosion resistance in 5% salt spray test
• No risk of Hydrogen Embrittlement which is the process by which high-strength steels become brittle and fractures following exposure to hydrogen. 
• As a water-soluble product, there are no hazardous materials giving a low environmentally impacted and comfortable work environment.
• Compliant with the Vehicle End-of-Life Directive and RoHS directive electrical and electronic equipment regulations.
• Excellent chemical resistance.