Important Factors To Consider While Selecting The Conveyor Chain Most Appropriate To Your Application

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.

For optimum performance of a conveyor chain, four criteria are crucial – strength, durability, resistance to fatigue and resistance to impact.

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.

Although the ultimate strength of any given chain will reflect the integrity of a certain material at a certain hardness, a high ultimate value does not necessarily mean that it is impervious to failure. The ultimate strength value is used for application engineering and deciding what type or size of conveyor chain to be used for various loads.

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.

There are options in base materials that take the above into consideration. Standard SAE 1045 steel with a hardness of 370 offers good impact and fatigue resistance, a reasonable level of durability as well as meeting minimum ANSI strength requirements. A hardness of 420 BHN of the same material improves its durability and strength but at the same time loses a bit of its impact and fatigue resistance. Microtuff-15 micro alloy steel also has good wearability, higher strength value, and top impact and fatigue resistance for the same cost as the 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.

As the conveyor chain wends its way around horizontal turns, the side load between the chain and the rollers or traction wheel instigates somewhat of a bending motion in the center link of the chain. The catalyst for fatigue is this bending process. Should the fatigue not be identified, the chain will not be immediately replaced. The incidence of failures are certain to increase exponentially. Because of this, the harder, more durable alloy chains are not recommended for heavily loaded systems with many turns at a rapid pace. Alloy chains work fine in straight line over and under conveyors or for slower, lighter loads on such conveyors in abrasive surroundings found in foundry cooling lines or incinerator drag lines.

Impact resistance is the conveyor chain’s ability to absorb shock loads without fracturing. There is an inverse relationship between hardness and impact resistance, but different materials at the same hardness have varying abilities to absorb impact without breaking. Impact resistance with regards to chain becomes a factor in many power and free systems.

In the case of loads that are often stopped and started, the chain, most particularly the pusher dog, is subject to impact failure if an impact resistant material was not used in its manufacture. Other possible points of impact on a conveyor are the loading and unloading sites. Similar to fatigue failures, impact failures happen with no warning, but they do not as a rule spread out as the fatigue failures do.

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.

Visit Wilkie Brothers Coveyors for more information on conveyors or to order Tsubaki Trolleys, Rapid Industries Rivetless Chain or any other related replacement parts.

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