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What is your advice for open roller chain lubrication?"
Effective lubrication of chains operating in a harsh, abrasive atmosphere can be challenging. The objective with chain lubrication is to place a small quantity of lubricant between the pin and the barrel in each link. Because it is impossible to directly inject the lubricant to the correct locations, practitioners try other methods, including running the chain through a bath, spraying, pouring and painting lubricant on the chain's outer surfaces.
For slowly turning chains, the oil bath is a practical, useful approach. Some attention is required to maintain an appropriate sump level and clean any excess lubricant off machine surfaces. Chains tend to be lubricated with whatever is handy.
Slowly turning, heavily loaded chains require a heavy body of oil. A medium gear or heavy circulation oil is a common choice.
For intermittent relubrication practices, any lubricant coating on the exterior of the chain creates an opportunity for airborne debris to build up and choke off oil flow to the internal components.
In addition, depending on the hardness of the airborne contaminant, this wetted material may act like a grinding compound working against the sprocket and barrel of the chain.
These applications are good candidates for lubricants with solid film additives mixed with a light, evaporating carrier. The light oil penetrates, carrying the solid additives to the contact point. The solid additives remain behind to provide “dry film” protection after the carrier has been displaced. The exterior of the chain also does not accumulate as much atmospheric contaminant.
A chain lubricant should have low enough viscosity to penetrate into critical internal surfaces and high enough viscosity, or necessary additives, to maintain an effective film at the prevailing temperature and pressure. The lubricant should also have the capability to maintain the desired lubricating qualities under prevailing operating conditions, and be clean and free of corrosives.
A good grade of nondetergent petroleum base oil usually is acceptable. While detergents are not normally needed, anti-foaming, antioxidizing and extreme pressure additives are often helpful. Impure oils should be avoided. Acids or abrasives in the oil can permanently damage the chain.
The chain manufacturer often uses grease or petroleum jelly as an initial lubricant. However, users generally should not apply greases to chains in service because they are too thick to penetrate into the internal bearing surfaces of the chain. Users should use grease only when fittings for injecting the grease into the chain joints are provided.
