Dual-extrusion system for plastic/wood fibre composites

Woodtruder, an advanced composite extrusion system by Davis-Standard, will allow processors “to use a greater array of basic polymers when processing wood-fibre composite products while eliminating the expense of costly wood fibre drying and blending equipment,” says Dave Murdock, a business area manager with Davis-Standard.

Set up in a tandem extrusion arrangement, the machine has a primary 28:1 parallel twin screw extruder and a mounted single screw, side-injection extruder. A crammer feeder conveys the wood fibre composite at a controlled rate into the primary extruder. The primary extruder utilizes a heating and vacuum venting system to eliminate moisture from the wood fibre, and separately heats and mixes the desired polymer in the side-injection extruder. The polymer is then injected at a controlled rate into the primary extruder.

Since the polymer joins the fiber in a molten state, it encapsulates the wood fibers, resulting in a thoroughly mixed, high-quality composite of up to 80 per cent wood fiber.

The two extruder approach makes it possible to process a variety of wood fibrous materials including peanut shells, rice husks, and wood shavings, as well as other recycled products like crumb rubber.

Stephen Sales Group, 905/940-5577; Auxiplast Inc., 450/922-0282

Circle Reader Service No. 115