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Chains designed for abrasive environments
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14/04/2004
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Problem: There are many instances where drive chains suffer from excessive wear as a result of their being used in an abrasive working environment.
One example brought to our attention is their use in the Horwich Castings foundry in Bolton, where roller chains on a conveyor removing hot boxes from a central mould machine were lasting a maximum of only six months. As castings are removed from the moulds, they are often still growing cherry red with heat. Hot moulding sand and small hot metal droplets are also expelled from the mould and frequently come into contact with the chain. External lubrication is not suitable for this application, especially if it helps abrasive material adhere to the chain rollers. Other examples include working in abrasive environments at lower temperatures and where external lubricant cannot be used because of a need to handle foodstuffs or pharmaceuticals.
Solution: In the case of the foundry, the wear problem was used by using Tsubaki's Lambda chain. This uses sintered rollers to lubricate the chain internally. Heat does not affect the self lubricating properties significantly and as the chain is dry to the touch, it does not pick up surface debris.
For food production, which in the case of dry products can also be very abrasive, and where external lubrication is not permissible, Jogen Roy of Kearsley Precision Engineers in Basildon told Eureka that the ideal solution is to turn to chain made of polyacetal links connected by stainless steel rollers.
Applications: The Lamba chain fitted on the moulding conveyors at Horwich Castings two years ago is still in operation and is not yet due for replacement.
Mr Roy claimed that the life of polyacetal chains used in the food industry was almost double that of conventional chains. The only downsides are that they are not suitable for fast running, and because polyacetal is not nearly as strong as steel, the links and sprockets tend to be somewhat larger and more chunky. TS
Tsubakimoto
Kearsley Precision Engineering Company
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Author
Tom Shelley
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