Causes and control measures for delamination and rough particles on the surface of thin particleboard

1. Causes and control measures of thin plate delamination

Cause:

Delamination refers to the separation of the bonded surfaces of particleboard due to lack of glue or poor gluing. Delamination is one of the common defects in the production of thin boards. Its main causes are as follows.

1) The slab moisture content is too high. Because the slab moves continuously in the continuous press, the steam generated during hot pressing can only be exhausted from the two sides of the slab. If the slab moisture content is too high, a large amount of steam will be generated in the core layer of the slab during hot pressing, making it more difficult to exhaust the slab and easily causing delamination.

2) Poor adhesive curing. Low adhesive curing degree or long curing time, too little or uneven adhesive application, insufficient or excessive curing agent can all lead to poor adhesive curing and easy delamination.

3) The hot pressing process is unreasonable. The hot pressing temperature is too low and the hot pressing speed is too fast, which results in the adhesive in the middle part of the slab not being fully cured and the slab being delaminated.

Control measures:

1) Control the moisture content of the slab. Thin slab production requires a lower moisture content in the wood chips. After drying, the moisture content should be controlled between 2.0% and 3.0%. After sizing, the moisture content of the surface chips should be controlled between 12.5% ​​and 13.5%, and that of the core layer should be between 6.5% and 7.0%.

2) Adjust the sizing formula. The amount of shavings glued must be precisely controlled. Too little glue will result in insufficient veneer bonding strength, while too much glue can easily cause delamination. Additionally, adjusting the amount of curing agent and adding an appropriate amount of urea can help improve veneer bonding strength.

3) Properly set the hot pressing process. Appropriately increase the operating pressure of the pre-press to facilitate air removal from the slab. Pay attention to fluctuations in the slab's moisture content. When the slab's moisture content is high, appropriately reduce the amount of glue applied or the amount of water added to the particleboard surface adhesive. Also, significantly reduce the hot pressing speed, and accordingly lower the hot pressing temperature and pressure.

2. Causes and control measures of coarse shavings on the surface of thin boards

Cause:

1) The grinder screen is broken, causing oversized shavings to directly enter the surface hopper.

2) The vibrating screen inside the paving machine falls off or is partially damaged or torn.

3) Improper setting of the fan power parameters of the surface airflow paving machine results in uneven paving of the surface shavings.

Control measures:

1) Check the grinder screen. If the screen is damaged, it should be replaced in time. Check whether the mesh size of the screen is appropriate. If not, replace the screen.

2) Check the vibrating screen inside the paving machine. If it is damaged, it should be replaced in time. The screen position and mesh size should be appropriate. If not, replace the screen.

3) The surface airflow paving machine should be in normal working condition to keep the paving airflow smooth and unobstructed.