The Manufacturing Process Continued
| Forming is the next step. As these photographs of forming machines illustrate, particleboard manufacturing is not a small-scale enterprise. |
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Within the former, a cascade of blended particles fall onto metal plates
(called caul plates) that are traveling on a moving conveyor. One type
of former is shown to the right. This lays down a continuous layer of
particles and is used when a homogenous board is being made (i.e. a
particleboard that has uniform sized particles throughout the
thickness). If the intent is to make a multilayered board, then several
of these formers are used in series. If, for instance, a three-layered
board is being made, with the faces of fine material and a core of more
coarse particles, three forming heads are employed. The first and third
in the series dispense blended sawdust or other finely refined
particles, while the second dispenses coarse particles, thereby building
up a three-layered particle mat.
(Image adapted from: Haygreen, J.G. and Bowyer, J.L., Forest Products and Wood Science - An Introduction, 3rd ed., 1996. Iowa State University Press.) |
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A multi-layered product can also be made using the type of former shown
here. This type makes use of air streams to move less heavy (finer)
particles outward, so that these are both the first and last to land on
the moving conveyor.
(Image adapted from: Haygreen, J.G. and Bowyer, J.L., Forest Products and Wood Science - An Introduction, 3rd ed., 1996. Iowa State University Press.) |
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Here is a photo of a three-layered particle mat that has been formed on
a metal caul plate. Note the fines on the surface and the relatively
coarse particles at the center of the mat.
(Photo: Roland Gertjejansen) |
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| The fiber mat is next weighed to make certain that the amount of blended particles fall within prescribed limits. Particleboards are made to pre-determined densities of about 38-44 lb/ft3 (610-706 kg/m3). If the weight of the fiber mat is either too high or too low, the particles are dumped onto a conveyor and returned to the board former. |
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