As a product of comprehensive utilization of renewable resources, particleboard is an important member of the wood-based panel family. Due to the low investment in production, low energy consumption, and extensive sources of raw materials, particleboard has many advantages such as high dimensional stability, good sound absorption and heat insulation, smooth surface, pollution resistance and anti-aging, and is often used as a substitute for natural wood. It is widely used in the fields of furniture manufacturing and architectural decoration.

How to effectively solve the problem of warpage and deformation of particleboard is very necessary. The distortion of the plate is caused by many reasons. Now let us take a look at the reasons for the deformation of the plate and how to avoid these problems.

1. Board paving problem

1. Cause

If the surface of the slab is uneven after paving, the slab after hot pressing will show an asymmetric structure. This will easily lead to too large density difference after pressing into a board, which will cause an increase in the internal stress of the board, and eventually warpage and deformation.

2. Solution

In order to ensure the dimensional stability of the particleboard, the principle of structural symmetry should be followed when paving the slab, that is, the shavings on both sides of the symmetrical center surface of the particleboard should try to choose materials with similar tree species, thickness, density and size. When setting the paving process parameters, the proportion of shavings on the upper surface layer should be appropriately increased to make up for the loss during transportation and ensure that the paving slabs with uniform thickness and smooth surface.

Second, the moisture content of the board

1. Cause

In the production of board, if the particleboard is partially dried unevenly, or the sizing is uneven, the moisture content of the particles on the surface and core layer of the particleboard will be unstable, which will cause warping and deformation of the board.

2. Solution

In order to stabilize the moisture content of the shavings after sizing, raw materials with similar moisture content should be selected, the surface of the board should be kept smooth and flat, and the glue should be as uniform as possible. When the shavings are dried, try to ensure that the outlet temperature of the dryer and the moisture content of the outlet meet the process requirements.

Three, hot pressing process problem

During hot pressing, the heat transfer is from the inside to the outside, so there is a high to low temperature gradient from the surface layer to the core layer of the slab. Therefore, if the upper and lower pressure plates use the same temperature under the same pressure, the heat of the upper and lower surface layers of the same pressure plate will be inconsistent, resulting in inconsistent curing strengths of the two surface adhesives of the particleboard, resulting in imbalance of internal stress, and warping of the particleboard. Curved deformation.

To correctly grasp the hot pressing process and the temperature change of the pressing plate, adjust the temperature of the pressing plate according to the actual production situation, so that the upper and lower surface layers of the slab have the same curing degree and similar strength to avoid different internal stresses. In addition, the slab can be processed by high-frequency preheating and spray steaming before hot pressing to increase the temperature of the core layer, so that the cross-sectional density of the slab tends to be uniform.

Fourth, the surface sanding problem

The profile density distribution of conventional particleboard is "saddle-shaped". If the amount of sanding on the upper and lower surfaces is inconsistent, the profile density curve in the thickness direction after sanding is asymmetric, and the upper and lower peak deviations are too large, and the board will warp and deform.

3. Solution

The thickness tolerance of the rough board should be controlled during hot pressing, and the upper and lower surfaces should be as consistent as possible during sanding, so that the profile density curve in the thickness direction of the sanded board should be symmetrical. This can ensure that the thickness of the plate is uniform and the surface of the plate is smooth and clean.

Fourth, the problem of sheet storage

If the storage method is unreasonable, even if the produced particle board is flat, the board may also be warped and deformed to varying degrees. Uneven stacking sites, unreasonable spacing or inconsistent top and bottom placement, etc., will cause uneven local forces when stacking the plates, resulting in deformation of the particleboard.

4. Solution

When the particleboard is stored, the finished wood-based panel must be stacked flat, not in a humid environment, and should be stored in a dry and ventilated environment. Keep the board stack flat and neat at the four corners, and place a flat heavy object on the top to prevent the board from deforming.

Although there are many reasons for the warpage and deformation of the particleboard, in the final analysis, the key factor lies in the balance of forces applied inside the board. In order to effectively prevent the warpage and deformation of particleboard, particleboard manufacturers should carefully analyze the causes of the problems, prescribe the right remedy, and take practical and targeted measures to better avoid such phenomena.