Rex® Roller Chains in special version for Gypsum Dryers

Article Tag:
industrial chain
A lot of work goes into making drywall. The gypsum dryer is the last step in the manufacturing process. During the vital drying step, a conveyor belt driven by a roller chain moves gypsum plaster boards through an oven. It may sound simple, but several key components and conditions have to work together to ensure quality drywall.

Gypsum Dryer Components and Conditions

  • Large pitch roller chains drive the roller conveyor. Roller Chain 24 B-1 acc. ISO 606 is one of the most common types of chain. The chains run tangential over the sprockets, which are positioned on the same shaft as the rollers.

  • The dryer is a hot, dusty environment. Temperatures can reach as high as 250°C. Because of the dusty conditions, relubrication of the chains during service is not always successful.

  • Because of the time it takes to dry the gypsum boards, distance between the deviating points is very long. You'll see more than 50 meters of space between deviating points.  Plus, several levels are often stacked over each other. The chain must run smoothly and be perfectly aligned tangentially over the sprockets from the rollers. When the chain links run in and out of the deviation sprockets, it’s critical that all links completely stretch out in the original position.

The Challenges of Drying Drywall

Gypsum dryers are a challenging environment. Factors in the process can wear down drying equipment, especially the chain. Temperature, dust, long distances between the deflection sprockets, and limited possibilities for relubrication can all lead to stiff chain joints. Another risk is when the chain links do not fully stretch out.  When that happens, there is a high risk that one chain roller will be lifted up from a sprocket tooth and the chain will then ”'jump” from a roller sprocket. The consequence: production comes to a stop.

Another possible danger is what’s known as ”twist” – a spiral deformation of a roller chain in running direction. You can see the effect of twist in Figure 1. Assembly errors, defective link plates, or wrong handling during the installation can all lead to twist.

Figure 1

A Chain Made To Avoid Stiff Joints And The Twist

Rex® has special 24 B-1 roller chain for gypsum dryers can help avoid stiff chain joints. The chain features a defined clearance between pins and bushings and between outer and inner links. This clearance is essential for the relubrication efficiency. In the dryer space, the only way for the oil to get into the chain joint is the gap between outer and inner plates. A special high-temperature synthetic oil (such as L12 for working temperatures up to 250°C) will provide the highest protection. Beyond the defined clearance, Rex's assembly and quality assurance methods ensure the function and longevity of our gypsum dryer chains.

Additionally, Rex tests roller chains for twist (Figure 2). These tests help circumvent any related complications.

Figure 2

Rex offers other chain varieties for gypsum dryers, including R 38-1 SH from the RexPro X series. Please contact us for any other information, help with chain selection or a commercial quotation.

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Jorg Heuer

Jörg Heuer started with Rexnord in 1996. Jörg trained as an agricultural mechanic and holds a degree in mechanical engineering. He is supporting the RegalRexnord Roller and Leaf Chain business as an Application Engineer. In this role, he provides customers with support in chain selection, chain drive design and all questions about maintenance and lubrication.  He also provides onsite assistance, trouble shooting and technical trainings.