In the production of fibreboard (MDF/HDF) the glued fibres are spread evenly on a continuously running conveyor belt. One also speaks of a fleece. The fibres are not aligned in a certain direction and are also evenly distributed over the thickness of the fleece.
In the production of particleboard and OSB boards, the properties of the finished board are determined by the alignment of the flakes and strands and by a multi-layer structure of particles of different sizes. This structure - the so-called mat - is formed in a spreading station, also called forming line. The tasks of the spreading station are:
- to distribute the flakes / strands evenly over the width
- to uniformly feed out the flakes / strands over the length
- to feed out the flakes / strands in a desired distribution over the thickness of the mat
With a standard furniture board, the flakes should be homogeneously distributed in the middle layer. The top layers or surfaces of the boards should later be tight and closed. The face sheets are therefore scattered separately from fine particles.
From the bunkers of the spreading station, the strands are transported via rollers to the spreading heads, which are equipped with orientation devices. Orientation of the surface layer in the direction of production is carried out with the aid of disc orienters, while the middle layer is oriented in the transverse direction by means of fan-type rollers. Both the weight of the spread mat and the proportion of surface layer to middle layer are permanently controlled by scales.
Electromagnets after each spreading machine ensure that any metallic foreign objects contained in the mat are removed to protect the press plates.