What Is a Dry Chain in a Saw Mill?

Function

• The dry chain is a conveyor belt or chain that transports dried wood. It is often the last step for wood as it is processed in a saw mill. After wood is dried in the drying kiln, it is carried down the dry chain, sorted and processed by operators. A dry chain landing table makes it easy for workers to manually pull wood from the chain and stack it for market. A similar conveyor component of the sawmill, the green chain, is used for the pulling and processing of hardwood lumber.

Manual Labor

• Dry chains are designed so one or more workers can access and pull the lumber from the conveyor. Depending on the capacity of the saw mill, the dry chain may be quite long and reach 120 feet or more. Workers are responsible for pulling, sorting, stamping, trimming, grading and packaging the timber for shipment. They stack the lumber as it is pulled from the dry chain, then band it together for selling. Many modern saw mills use mechanical sorters to sort the lumber by length, width and thickness.

Saw Mill Operations

• You can better understand the function of a dry chain by considering the entire operational process of a mill. First, the bark is removed from raw logs. The logs are then cut into smaller sizes, with many cut into boards. The boards are edged, trimmed and sorted by size before entering the dry kiln. After the boards are pulled and sorted at the dry chain, they can be molded for various purposes, such as flooring or exterior siding. Leftover shavings and chips from cutting and trimming the boards can be collected for marketing as wood chips.

Drying

• Before entering the dry chain, moisture must be removed from lumber. The drying kiln is responsible for heating the wood and removing moist air as it evaporates. But some lumber mills may employ an air drying method. If you are using a saw mill at home, you may air dry your wood. The lumber should be between 1 and 2 inches thick for optimal drying. Set stacks of lumber 1 to 2 feet off the ground on supports that are spaced no more than 2 feet apart. Cover the wood with plywood to protect from rain and sunlight, and wait until wood is at a moisture level of 15 to 20 percent. Depending on conditions, this may take at least a month or longer.