Sanded plywood is a high-quality board made of multiple layers of veneer (usually an odd number of layers) as the base material. These veneers are arranged vertically and hot-pressed according to the texture, and then processed by precision sanding. The core of its production process is to use progressive sanding technology from coarse sand (80-120 mesh) to fine sand (240 mesh and above) to effectively remove burrs, glue marks and minor unevenness on the surface, ensuring that the surface roughness of the final product reaches a mirror-level flatness of ≤3μm. This high-standard surface treatment allows sanded plywood to be directly used for painting or veneer, meeting the strict requirements of industrial production. This process not only improves the aesthetics and practicality of the board, but also enhances its application value in high-end furniture manufacturing and interior decoration.
Sanded plywood has good dimensional stability, durability and strength, and is widely used in furniture manufacturing, interior decoration, building formwork and other fields. Due to its smooth surface, it can be directly painted or veneered without the need for additional surface preparation, thus saving construction time and cost.
When choosing sanded plywood, you should pay attention to check whether its surface quality is uniform and flawless, whether there is degumming, and whether the moisture content meets the use requirements, etc., to ensure the quality and service life of the final product. In addition, according to different uses, you can also choose sanded plywood of different grades and specifications.
Core performance advantages
Physical properties
Flexural strength ≥ 30MPa, moisture content controlled at 8%-12%, with excellent dimensional stability and deformation resistance;
Surface density increased by 15%-20%, significantly enhancing wear resistance and impact resistance.
Processing adaptability
Surface flatness error <0.1mm/m, can be directly processed by UV coating, veneer lamination and other high-precision secondary processing;
Reduce paint loss rate by about 25%, saving more than 30% of pre-painting processing time.
In order to prevent the quality defects of sanded plywood and ensure that it meets the expected performance and appearance standards, we can start from multiple links such as raw material selection, production process control and finished product inspection. The following are some specific preventive measures:
Raw material selection:
Select high-quality veneers as the base material, ensure that their moisture content is moderate (usually between 8%-12%), and avoid insufficient bonding strength or other quality problems caused by too high or too low moisture content.
Use high-quality adhesives and adjust their ratios according to environmental conditions to ensure the bonding effect.
Production process control:
Gluing process: Ensure uniform glue application and control the amount of glue applied to avoid too much or too little. At the same time, pay attention to the applicable period of the adhesive and do not use expired adhesives.
Assembly process: Accurately arrange the veneers to ensure that the texture direction is correct and there are no foreign objects between the veneers to prevent problems such as bubbling or local debonding.
Hot pressing process: Optimize hot pressing parameters (such as temperature, pressure, time) to adapt to different types of glue and board thickness to ensure strong gluing and reduce warping.
Sanding process: Reasonably set the sanding parameters, including the selection of sanding belt grain size, and sanding speed, to obtain the ideal surface smoothness and flatness. Regularly check and maintain the sanding equipment to avoid surface defects caused by equipment problems.
There may be some common quality defects in the production process of sanded plywood, which may affect its performance and aesthetics. The following are several typical quality defects:
Low bonding strength: This is usually caused by poor quality of the adhesive used, improper control of hot pressing conditions (such as temperature, pressure, time), too high or too low moisture content of the veneer, insufficient glue application, etc.
Bubble and partial debonding: This type of problem may be caused by too fast pressure reduction speed, insufficient glue pressing time, too high moisture content of the veneer, uneven glue application or the presence of inclusions.
Warping: This is caused by uneven internal stress of the plywood. Common reasons include inconsistent moisture content of the front and back boards, unreasonable matching of veneers of different tree species, twisted veneers, and insufficient temperature of individual hot pressing plates.
Debonding at corners: This situation usually occurs at the edge of the board. It may be caused by insufficient pressure caused by wear on the corners of the pressing plate, misalignment of the corners of the slab, and uneven force when the board is placed crookedly during installation.
Glue penetration: glue appears through the surface of the veneer, usually due to factors such as too thin glue, too much glue, too deep cracks on the back of the veneer, and too high moisture content of the veneer.
Core board lamination and gap separation: improper gaps reserved during manual core arrangement, misalignment or overlap of core boards during board installation, etc. can cause this defect.
Surface defects: If the surface of the plywood after sanding is still uneven, scratched, or dented, it may be caused by improper sanding process or equipment problems.
Technical principles and processes of sanding process
1.Process core: layered progressive sanding
Sanding treatment uses multiple sanding belts to cut the plywood surface in layers. Its core processes include:
Coarse sanding stage (80-120 mesh): Use high-cutting force sanding belts to remove 0.2-0.5mm burrs, glue marks and obvious bumps on the surface, and control the flatness error within 0.3mm/m;
Fine sanding stage (180-240 mesh): Fine grinding to surface roughness Ra≤3.2μm, eliminating scratches caused by coarse sand;
Fine sanding stage (320 mesh and above): Use flexible sanding technology to achieve an ultra-smooth surface of Ra≤1.6μm to meet the needs of high-gloss coating.
2.Key equipment and parameter control
Equipment type: wide belt sander (high efficiency, suitable for mass production), special-shaped sander (for processing curved surfaces or carved boards);
Process parameters: belt line speed (20-30m/s), feed speed (8-15m/min), pressure (0.5-1.2MPa), which need to be dynamically adjusted according to the hardness of the wood.