Breaking Load is not the way to Specify Chain

It is important to properly understand the role played by wear resistance and fatigue resistance in the performance of a chain so that breaking load, or tensile strength, does not become the primary selection factor.

You know better than anyone else how your machinery operates. You will know the speeds, loads and operating conditions that the chain has to cope with.

Do not specify chain based on breaking load

Under normal conditions, a chain should not be operating at anything close to its breaking load. If it is then the drive setup should be reviewed and perhaps a different chain should be specified.

Consider the relationship between the number of cycles and the load exerted on a chain. The lower the load, the higher the number of cycles it can endure. If you impose one massive load, that could be enough to break the chain. Therefore you need to understand the normal operating loads for the application and specify the right chain accordingly.

In order to achieve long wear life it is essential to have specialist component design, consistent material specification and the correct balance of heat treatment. Heat treatment has an important role to play in the mechanical strengths of components, but it's a fine balance. Prolonged heat treatment to achieve high tensile strength can leave parts brittle and with increased vulnerability to fatigue failure.

Of great importance for longer working life is the chain's ability to manage the applied loads and provide fatigue resistance well above the application's anticipated working loads. Reliable chain manufacturers will know the fatigue limits of their products and it is this that engineers should be taking into consideration rather than breaking loads.

So, let's put thoughts of breaking load to one side. Chain should be operated well below any load at which it could break. In fact, permanent damage will occur if the load on a chain is more than the elastic limit of the steel parts. Chain should be operated below its endurance limit to ensure that wear is the mode of failure, rather than fatigue, or even complete failure because of overload.

In the same way that a car tyre should eventually wear to the point that it needs to be replaced, but should not fail abruptly, so too should a chain need replacing because it has worn. The important decision is to choose a chain that will take the maximum amount of time to reach that level of wear.

To help make chain selection easier and to ensure that engineers get the optimum value and working life out of chain, Renold offers a sophisticated chain selector that takes all the hit-and-miss out of the increasingly complex choices. The selector is at and will identify the best chain for any given application. That is, the smallest chain available that will last a minimum of 15,000 hours — or 30,000 hours for Renold Synergy — based on factors such as speed, load and the power ratings of the user's application.

The Renold Chain Selector is quick and easy to use. Your detailed results can be downloaded and provide a simplex, duplex and triplex option to meet your criteria including corrosion resistance, resistance to abrasive debris, lack of lubrication or the need for high performance.

If you would assistance or advice on any aspect of chain selection, call Renold on:

+44 (0)161 498 4600