The Airlaid process
FOSEC is the name of the dry-forming process that further refines our own Star Fluff CTMP grade to the Luna absorption product. Before dry forming commences, the bales must be unwrapped and the moisture content adjusted. The pulp is subsequently dry defibrated, that is, the fibres are finely separated in two steps and then transported to a buffer tank.
Screw feeders deliver the fibre to the forming machine, which is designed according to the Kröyer principle, with two forming heads and a forming machine wire with accompanying vacuum boxes. The fibres are suspended in air in the forming heads above a fine-meshed drum screen, and with the aid of a vacuum, the fibres pass through the net where they are deposited to form a web on the machine wire.
The web is coarsely trimmed and transported to the calendar rolls, which are heated. The surfaces of the rolls are smooth or patterned, depending on the product to be produced. When the web is compressed under high pressure in the heated calendar rolls, the density increases and the required strength properties are developed.
Following calendaring, the web passes a camera with an image analysis program, metal detector and an on-line quality control system. The properties that are measured are basis weight, thickness and moisture. The information is used to both automatically regulate the process and to determine the finished product’s quality.
The web is then trimmed and wound to the desired diameter in the winder, which is specially designed to directly cut the web to the desired roll width, down to a minimum of 45 mm.
With the aid of a specially designed reeling robot, the finished rolls are sorted and stacked on pallets, which are thereafter wrapped and transported to SCA Transforest terminal for onward transport by rail, truck or boat to our customers.