The phenomenon of chain stretching is more appropriately called chain link deformation. In fact, the chain-link itself does not become longer. It refers to the deformation of one or more chain links that constitute the chain. When the roller chain is stretched, it will seriously affect the structure and performance of the chain. The following is the method to prevent the chain from stretching.
Signs of Chain Stretch
Chances are that you will see signs of chain stretch long before a chain breaks. In fact, breakage is very rare with modern chains. More common is one or more of the following symptoms:
(1) Excessive rattling, grinding, or other unusual noises coming from the chain drive.
(2) Wear on the teeth of sprockets, often in a characteristic hook shape.
(3) In the case of timing belts, a variation in timing is seen with a timing light.
(4) If a tensioner is being used, the movement of the tensioner can be monitored to see if the required amount of tension has increased.
The most common way to measure chain stretch is through the use of a ruler or tape measure. One can also make use of various simple tools that fit into the spaces between pins. Often these will be provided by the manufacturer.
The ways to prevent the roller chain from stretching
Choose the right type of lubricant
The most important factor in preventing chain stretch is lubrication. If roller chains are poorly lubricated, stretching will take place very quickly. When a chain has elongated 3% of its original length, it must be replaced.
Another highly significant factor in chain stretch is the accumulation of dirt particles between parts of a chain. These particles form a paste with existing petrochemical lubricants, and they will cause pins, rollers, and bushings to lose material rapidly, again resulting in an overall elongation of the whole chain.
Choose lubricants that are good at preventing this type of wear because they will produce a dry film instead of a sticky layer. Viscous oils and greases only accumulate dirt, rust particles, and other types of dirt, while special lubricating products do not accumulate particles at all. Instead, they form a dry layer that prevents the particles from sticking. No abrasive paste, no excessive wear, can extend the life of the roller chain by 50%.
Check chain strength regularly
(1) Tensile strength
How many loads a chain can bear all at once before breaking.
(2) Fatigue strength
Dependent on the quality of chain materials.
Remove wax layer or preservatives in time
When new roller chains arrive from the factory, they are often coated in wax or another layer of preservative to protect them during transport. It’s important to note that this layer is not intended to serve as chain lubrication, but is applied only for shipping purposes. Furthermore, if this layer is not removed, it will prevent lubrication from reaching the inner workings of the chain, such as between the pins and bushings, or between the bushings and the links.
To effectively remove this protective layer, we recommend immersing the chain in a degreaser for a period of 15 minutes, followed by air-drying with a high-pressure air gun or air hose. Once all degreaser has been removed, lubricate the chain properly according to the manufacturer’s recommendations.
If you want to know more information about roller chains after reading the above, please contact us to get it.
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