Reasons to Avoid Chain
1- Cables work in almost pure tension, which simply means that the load and force is directed through the center of the cable. The cable is not loaded in bending until it flexes. Chain is loaded in bending which causes high tensile stresses on every link in the system. See Note #1 in figure. Tensile stresses cause metal fatigue.
2- To overcome these stresses, chains rated for the same tension as a cable are much heavier than cable. A chain conveyor company doesn’t choose to use a heavier chain because they want to, they have to.
3- Heavier chain means more of everything that is bad for a conveyor, and these are listed below.
See notes 4 thru 6 as to why these are bad.
- More weight. For a similarly‐sized system, their chain weighs more than 3 times what our cable lighter cable weighs, and almost twice what our heavy cable weighs.
- More friction
- Higher tension (which means even more friction)
4- More weight means more power is required to lift the components of the system even when running empty. Clients waste energy and money moving the conveyor, not product.
5- More weight also means more losses due to friction. Energy is required to pull chain through the tube. Friction is the problem tube conveyors must overcome.
6- Tension is a necessary part of a functioning conveyor. Tension in the system keeps the cable and/or chain engaged with the sprocket and keeps slack out of the system. However, tension creates its own challenges, and excess tension means even more challenges.
- Higher tension means more force is required to pull chain through sweeps.
- More force through sweeps means more wear in the sweeps and on the discs. It means more damage to the product as it is ground between the discs and the sweeps.
- The discs, being pulled against the inside of the sweeps with more force will make more noise.
- Higher tension and increased force requirements mean larger, more expensive motors are required.
- More energy is consumed. In markets where electricity is expensive, a cable system pays for itself very quickly over a chain system.
- To supply this tension, really heavy springs are required. These springs present a greater safety risk than the lighter springs we are able to use. The heavy springs mean additional safety precautions are needed when the system needs maintenance.
- Adding more tension means each link is under even more stress than what was mentioned in note 1.
h. Adding more tension means each link‐to‐link contact point is under increased stress. See Note #2 in the image.
- Increased stress at the contact point means increased damage occuring between links. Where does this abraded or broken material go? Directly into the product.
- The abraded material makes the links “longer” resulting in a longer chain. If even 0.005” is worn away from each link at each connection point, a 200‐foot long chain will stretch 9.38 inches.
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7- Chain links create a pinch‐point that will both damage product that gets in the zone prior to a sweep and can cause misalignment or excessive abrasion. See note in the image.
8- And perhaps the most significant concept in favor of cable is the following: When lives are at stake, what do companies use to lift or move people and heavy equipment? What are used in the following applications, chain or cable?
- Suspension bridges
To dispute the idea that cables can fray, we can use coatings. A chain system is more likely to wear out all the sweeps in their system before one of our cables will fray. So maintenance isn’t an argument.
We have over 40 years’ experience, enough to know that cable is the best choice in this application. We have moved more materials in more countries around the world, and we still use cable. We have the money and the resources to choose chain, but we recognize and understand its inferiority in drag conveyors.