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Conveyor chain is used throughout the world in a wide range of applications varying from sprinkler movement in the agriculture industry to moving vehicles on a production line in an automotive assembly plant. If something requires conveyance from point “A” to point “B” continually, whether it is being assembled, painted, washed, inspected, or stored for future use, chances are good that conveyor chain is at the heart of the system.

There are four critical criteria required for maximum performance of a conveyor chain. They are ultimate strength, wearability, fatigue resistance and impact resistance.

The weight in pounds required to break the chain on a linear plane is the measurement that determines the ultimate strength of the chain. The usual method of testing is by use of a tensile testing machine. The minimum strength values for each size of chain are dictated by ANSI. The material of which the chain is made, its manufacturing process, and hardening specifications used in making its components consisting of center link, side link, and pin are controlled by the manufacturer and determines the strength of the chain.

The ultimate strength of a chain is determined by the integrity of the material at a specific hardness. Although a high ultimate value will not of necessity make it fail-proof. The ultimate strength value determines what type or size of conveyor chain will be used for a variety of loads and is used mainly for application engineering.

A conveyor chain’s durability value is the most subjective value to consider when comparing chains. Factors affecting it’s durability are lubrication, loads, chain speed, and system design among others. A manufacturer controls only the hardness factor that impacts the other three criteria. It is a fact that the harder the chain the higher its durability factor but along with this comes a lower resistance to fatigue and impact. The harder the chain the less resistance it becomes to fatigue and impact.

Different base materials offer some options in this regard. For instance, standard SAE 1045 steel at a hardness of 370 has good impact and fatigue resistance, reasonable wearability, and meets minimum ANSI strength requirements. The same material at a hardness of 420 BHN would improve its wearability and strength but lose some of its impact and fatigue resistance. Microtuff-15 micro-alloy steel on the other hand, has good wearability, higher strength, and excellent impact and fatigue resistance at the same cost as SAE 1045.

Fatigue resistance means that the material used is able to hold up under continuous bending, twisting, etc without breaking. It is quite possibly the conveyor chain’s most important asset or liability. Until the material shows signs of fracture, however, the fatigue level is not readily measurable. In today’s manufacturing world with its higher production rates, heavier loads, more convoluted chain paths with tighter radius turns, the chain is vulnerable to more subtle bending and twisting than ever.

While the chain moves around its horizontal turns, the side load between the chain and the rollers or traction wheel makes for a subtle bending motion in the center link of the conveyor chain. This particular movement is the catalyst for fatigue. Should the fatigue go unnoticed and therefore, the chain is not replaced at once, the instance of failure is diminished.

The term impact resistance defines the conveyor chain’s capability to absorb shock without breaking. Hardness and impact resistance have an inverse relationship, although there are many materials at the same hardness which have varying degrees of ability to absorb impact without fracture. A chain’s impact resistance is an important factor in many power and free operations.

With loads being stopped and started frequently, the chain, especially the pusher dog, is susceptible to impact failure if it is not manufactured from an impact resistant material. Other potential impact points on a conveyor are the loading and unloading stations. Impact failures, similar to fatigue failures, occur without warning, but unlike fatigue failures, they don’t necessarily multiply.

The consideration of the above criteria is very important when selecting a conveyor chain for optimum performance of a system. If the appropriate chain is used for the specific purpose intended, the life of the system will be prolonged, and the risk of failure diminished.

For more information on Conveyor Parts or Rebuilt Conveyor Parts please visit Wilkie Brother Conveyors.

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