By Peter Church
With the right specification and lubricant, leaf chain can successfully operate in temperatures from -20°C to +°40C.
I was recently asked for advice from a customer who was sending a machine to Antarctica. The average winter temperature at the South Pole is about -49°C, which is hard to comprehend, given that the coldest day in Letchworth this year was -5°C – and I thought that was extreme!
When working on new designs, I generally consider an operating range of -5°C to 20°C.
Catering for the change in leaf chain component performance in different temperatures could be as simple as using a special lubrication or it may require increasing the chain size to handle the drop in tensile strength.
Where necessary, leaf chain can be built using specialist materials to withstand extreme temperatures.
What happens to leaf chain in low temperatures?
Conveyor chains can be found working in cold environments such as blast chillers and ice tunnels used in food preparation. A common low temperature application for leaf chain is on forklifts working in frozen storage facilities anywhere between 1 to -50°C.
When leaf chain operates in low temperature environments -10°C (15°F) or below, the chain links typically start to become les ductile. At -30 ºC low temperature brittleness becomes a factor and the chain loses its resistance to shock loads.
As the temperature lowers, the lubricant thickens, reducing the articulation and flexibility of the leaf chain. There are specialist lubricants available that cope better in low temperatures.
What happens to leaf chain in high temperatures?
Some roller chains operate in extremely high temperatures, such as in ovens or furnaces. Leaf chain is generally fitted to materials handling equipment working outside or in warehouses. Normal operating conditions in our UK warehouse are usually somewhere in the range of 15°C to 30°C, but in warmer climates forklift trucks and other machines may be working outdoors in 40°C or higher.
Like all metal parts, temperature will impact on the performance of leaf chain. Over 148 °C (401 °F), there is a reduction in surface hardness and the wear rate will increase. Above 260°C (500 °F), the tensile strength and ductility will decrease. Above 60°C attention will need to be paid to the lubrication type and application intervals.
Coping with temperature variance
One of the biggest environmental challenges for leaf chain fitted to materials handling equipment is not withstanding extreme hot or cold temperatures but coping with temperature variance.
Refrigerated storage temperatures usually range from 0 to 5°C. Many warehouses of this type have separate cold storage rooms as different products need to be kept at different temperatures. For example, meat products are stored just below freezing, while dairy products are kept just above freezing.
When forklift trucks are operating in these environments, condensation can form on the chain while in warmer areas or loading zones and freeze again as the vehicle moves into the cold storage. This can quickly lead to stiff joints, as well as rust and corrosion over time.
The use of a corrosion resistant leaf chain and a chain lubricant with water-repellent properties can alleviate this problem.
If you need a leaf chain to work in extreme hot or cold environments or cope with temperature variations, feel free to get in touch with our application experts for further advice.