Why the right lubrication matters for the service life of leaf chain

Even when engineers are confident that they’ve lubricated their leaf chain sufficiently, they can still encounter issues with friction corrosion, pitting and more.

So what steps should you follow to ensure your chain lubricant is applied to achieve optimum performance life?

And how can you be sure you’ve selected the right lubricant for the job?

When carried out correctly, chain lubrication can solve, or in many cases prevent altogether, a raft of potential industrial chain problems – from noisy operation, surface rust and stiff joints to twisted pins, broken links plates or unacceptable levels of chain elongation.

A properly lubricated chain can also extend the service life of the chain by as much as sixty-times, when compared to that of a similar dry-running chain.

Even relatively short periods of dry-running of industrial chain have been shown to lead to considerably compromised operational life. And incorrect, or inadequate, lubrication is recognised as the root cause of approximately 60% of all industrial chain defects.

When cleaning is unavoidable…

Leaf chain applications that are required to operate in arduous, dusty or dirty conditions can be vulnerable to a high degree of soiling. Any substantial build-up of dirt increases the risk of lubricant not being able to reach the inner chain joints.

The cleaning of chains however, can have a detrimental effect on chain wear-life. So, if cleaning your leaf chain is your only option, it is going to be important to consider the way in which you go about it.

It is usually recommended that industrial chain is only ever cleaned with a paraffin derivative. The use of steam jets, cold cleansing agents or caustic or acidic agents is generally not advised due to the risk that they pose to the integrity of the chain.

In the event of significant soiling, it may be necessary to clean your industrial chain using steam jet equipment. The key to minimising damage to the chain will be to ensure that you use only pure water or steam, with no form of potentially harmful additive.

After steam cleaning you will need to apply compressed air to the chain to remove any excess water from the surface of the chain and the inner joints. And be sure to move the chain several times throughout the process so you know you’ve targeted every surface.

Re-lubricating your chain

Once your chain has been thoroughly cleaned and dried, it is also likely to thoroughly “degreased” – which means you will need to re-lubricate the chain.

The method of lubrication is extremely important. We recommend manual application of the lubricant by brushing the lubrication into the pin and plate area.

If you use a spray you will need to ensure it has a focused beam, with a sufficiently low viscosity to reach the internal surfaces, and a carrier solvent or penetrating component that evaporates to increase the operating viscosity once inside the chain.

Another important consideration is to ensure that the chain is in a completely slack condition.

If the lubricant is only able to reach the exterior of the chain, and not able to penetrate the chain joints, then this can result in insufficient lubrication of the pins and plates.

Choosing the best lubricant

The lubricants that used with leaf chain are often required to withstand high surface pressure, irregular re-lubrication levels and exposed operation.

When considering which lubricant to use, it is worth keeping in mind the following factors:

• The ability of the lubricant to provide adequate corrosion protection
• Its capacity to penetrate through water
• Its consistency of viscosity following application
• The lubricant’s adhesive properties
• That the layer thickness and protective film can withstand mechanical aggression such as driving rain or hail

The lubricants Molykote (MKL-N) and Kluber Structovis (BHD 75 S) have been found to be especially suitable for leaf chain.

Lubricants that are required to work in low temperatures will also need to be resistant to hardening in order to prevent friction within the links that can lead to immobility of the chain.

Lubrication is a highly specialised area of engineering.

If you have any questions about the best form of lubricant to use for your particular leaf chain application, seek guidance from your industrial chains manufacturer who will be able to provide advice on the specific products and surface finishes to resolve your lubrication problem.