Important Factors To Consider While Selecting the Conveyor Chain Most Appropriate to Your Application
The universality of the conveyor chain in various applications from moving vehicles down the line in auto production to the movement of sprinklers in agriculture can be seen around the world. Whenever something must be moved from point \”A\” to point \”B\” continuously no matter if it is to be assembled, washed, painted, inspected or heading for storage, you will undoubtedly find a conveyor as the basis 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.
Conveyor chain strength is normally measured in the quantity of pounds necessary to bust the chain on a linear plane. This is tested by a tensile testing machine and the values of the minimum ultimate strength for each size chain are dictated by ANSI. In the process of making the chain, the manufacturer controls its strength by the choice of material, manufacturing processes, and the hardening specs used in the components of the chain, which are its center link, side link and pin.
The integrity of the material at a certain hardness determines the ultimate strength of the chain, but a high ultimate value does not by itself indicate that it is not subject to failure. This value rather is used for application engineering and in the decision as to what kind or size of conveyor chain should be used in various loads.
The Wearability of conveyor chain is probably the most nebulous value to document when comparing chains. Lubrication, loads, chain speed, system design, etc., are all outside factors that impact wearability. The only value that a manufacturer controls that would impact wearability is hardness. Unfortunately hardness has a major impact on the other three chain criteria. Obviously the harder a chain is the more wearable it would be but it also becomes less fatigue resistant and less impact resistant as the hardness increases.
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.
What fatigue resistance indicates is the material\’s capacity to endure continuous bending, twisting and so forth without breaking apart. This is possibly the conveyor chain\’s preeminent asset or liability. The quality of fatigue is not readily quantifiable until the material shows signs of fracture. Modern factories have higher rates of production, heavier overall chain loads, more maze-like chain paths with tighter radius turns, and the chain is more apt to undergo more subtle bending and twisting than in years past
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.
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.
In loads with frequent stops and starts, the chain, in particular the pusher dog, is vulnerable to impact failure if not made out of impact resistant material. Loading and unloading stations are other possible sources of impact. Both impact and fatigue failures do occur without any warning. Impact failures on the other hand do not by nature increase once they begin.
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 Rivetless Chain, Used Rivetless Chain, or any other conveyor parts, please visit Wilkie Brother Conveyors.
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