Discussion on the method of preventing deformation of large-sized plates

In recent years, large-format panels (such as 9-inch panels) have increasingly been used for wall panels and wardrobe panels. This not only adds a high-end, elegant feel to the overall decor, creating a sense of spaciousness and three-dimensionality, but also improves wardrobe space utilization and ease of use, while saving production and installation costs. This has become a new favorite in high-end decorating, gaining increasing popularity among consumers. However, the excessive length of large-format panels increases the risk of deformation. This article analyzes panel deformation from several perspectives and summarizes several methods for preventing large-format panel deformation for reference in the relevant industry.

1. Selection of plain board

1.1 Board selection

Generally, the higher the density of artificial board, the greater the stress and tension within the board, and the higher the chance of deformation. For this reason, particleboard is preferred over fiberboard for large-format boards. This is because particleboard generally has a lower density than fiberboard, making it more resistant to deformation. It also offers superior environmental ratings and load-bearing capacity.

1.2 Production equipment for plain boards

Currently, the biggest difference in particleboard production equipment lies in the hot press. The development history of particleboard production equipment shows that hot presses for particleboard production have evolved from multi-layer presses to single-layer large-format presses to continuous flatbed presses. Due to the size limitations of single-layer and multi-layer hot presses, the 9-foot-large boards currently on the market are essentially produced using continuous flatbed presses.

1.3 Structure of plain board

One of the main causes of board deformation is structural asymmetry, which can be caused by a variety of factors. Analyzing raw board materials, the most common factors contributing to board deformation are: 1) asymmetry between the upper and lower surfaces (inconsistent thickness or peak density); and 2) excessive density deviation. Currently, large-scale particleboard factories in China have invested over 100 million RMB in equipment, resulting in relatively sophisticated equipment, making these situations uncommon.

Analyzing the core layer structure, the performance of flakers, the core equipment for particleboard production, has significantly improved over the past few years. Some companies that began production after 2017 are now able to process core layer particles into "flaked particles" approximately 3 cm long and 1 mm thick, effectively increasing the core layer particle's aspect ratio. This overlapping connection method, similar to that used in oriented strand board (OSB), increases the bonding area of ​​the core layer particles, making the board more dimensionally stable and thus improving its resistance to deformation. This is also the most critical factor in improving the deformation resistance of particleboard.

1.4 Impurity content

Many years ago, particleboard was generally viewed poorly by consumers due to factors such as high levels of impurities, poor production equipment, low environmental ratings, substandard physical and chemical indicators, unsatisfactory performance, and inadequate market regulation. In recent years, with the upgrading of equipment and increased market demand, some high-end particleboard factories in China have optimized their equipment configurations and, through the use of licker-in rollers, vibrating screens, and airflow sorting, have removed impurities such as bark, stones, sand, and metal from the raw materials. This has resulted in a purer and cleaner product, while also reducing the impact of impurities on adhesive bonding and improving the bond strength between the particles. This has effectively increased the particleboard's resistance to deformation, facilitated subsequent veneering and cutting, and enhanced performance.

2. Finishing

The asymmetry of the plate structure is an important cause of plate deformation. The surface processing of the plate can easily destroy the symmetry of the plate. The possible reasons are as follows:

1) Hot pressing veneering process. Due to the difference in the time that the boards are in contact with the upper and lower hot pressing plates, there is often a certain temperature difference between the upper and lower hot pressing plates. The temperature difference needs to be adjusted accordingly according to different climates, different wood species, different moisture content, different thickness of boards, etc.

2) Post-veneering curing. Veneer panels maintain a relatively high temperature after veneering. Directly stacking and curing the panels will delay the release of this temperature, potentially leading to aging of the adhesive paper and deformation of the panels. Using a panel turner to dissipate heat significantly reduces the panel temperature, effectively preventing aging of the adhesive paper and deformation.

3) Choice of finishing materials. Designers strive to create aesthetically pleasing pieces, often employing a combination of different finishing materials. However, the combined use of different finishing materials can easily disrupt the structural symmetry of a panel, such as using impregnated film paper on one side and glass, PET, or UV paint on the other. While this effect may not be noticeable immediately, over time and with environmental changes, the likelihood of deformation due to asymmetry increases. Choosing the same finishing material on both sides of the same panel effectively reduces the risk of deformation.

3. Storage and transportation

There are also factors that may cause deformation of plain boards or decorative panels during storage and transportation.

2) Climate change is also a common factor causing deformation. In areas with heavy rainfall and high humidity, or during hot and rainy seasons, the wood panels continuously absorb moisture, which can reduce their physical and chemical properties and performance, and can easily lead to deformation. In these cases, the panels should be kept dry and well-ventilated during storage and transportation to minimize moisture absorption.

4. Installation and use

The main factor that easily causes deformation in this process is climate. Environments such as heavy rain, high humidity, and high temperatures make the board susceptible to moisture. Even after the veneer and edge banding processes, if the punched areas are not treated, or if the pre-milling is insufficient before edge banding, the edge banding pressure is low, resulting in loose edge banding, this can also cause local moisture in the board.

During the rainy season in some southern regions, indoor humidity is extremely high, even forming water droplets on the walls. This means that the panels are partially submerged in water, which can easily cause them to deform or even mold. In such an environment, ventilation and dehumidification should be maintained to maintain a relatively dry indoor environment. Moisture-proof panels can be used if necessary.

5. Conclusion

The main factors that lead to deformation of large-sized boards include asymmetric raw board structure and the destruction of symmetry during processing, storage, transportation, and installation. In view of these factors, it is recommended that when selecting large-sized boards, priority should be given to particleboard with a core structure of flaky particles, high purity, and produced on a continuous flat-pressing line. Particleboard has strong plasticity, high flatness, and high environmental performance. The flaky particles in the core layer make the connection method more stable. The high purity reduces the impact of impurities on the adhesive effect. The continuous flat-pressing line production is conducive to stabilizing product performance and ultimately improving the board's resistance to deformation. During surface processing, do not destroy the original symmetry of the board. During storage and transportation, strengthen management to avoid deformation of the board caused by human factors. During installation and use, reduce the impact of the environment on the board, and choose moisture-proof board when necessary.

This article was published in the 10th issue of "China Wood-Based Panels" in 2020.

Citation format:

Zheng Haitao, Li Fei. Discussion on the prevention method of deformation of large-sized panels[J]. China Wood-Based Panels, 2020, 27(10): 29-30, 36.