One. What are the causes of warping in plywood?
1、Transformation due to differences in moisture content
In the production of plywood, such as uneven drying or inconsistent fiber distribution in particleboard or medium-density fiberboard, or uneven application of adhesive during the manufacturing process, inconsistencies in moisture content, curing of the adhesive, and varying moisture evaporation can lead to uneven stress distribution, resulting in warping.
2、Deformation caused by improper hot pressing process or issues with the press machine itself.
The plywood may deform during the pressing process due to factors such as:- The press's own conditions, such as board deformation, insufficient temperature of individual hot press plates, or uneven pressure.- Improper handling of the hot pressing process, such as too high or too low temperature or excessive pressure.
3. Deformation caused by asymmetrical construction.
Asymmetrical construction is a key factor in generating internal stresses within the panel. Differences in the wood species, fiber orientation, thickness, moisture content, and number of layers of the plywood, as well as variations in the single-ply sheet's twist, are also key causes of warping and deformation.
Two. How to restore warped plywood
1. When designing composite panels and support systems, it is essential to consider the self-weight of the panels and supports, the loads imposed during construction, and the lateral pressure generated during concrete placement and setting. This ensures that the composite panel and support system have sufficient load-bearing capacity, stiffness, and stability.
2、The spacing between the support beams should ensure that no deformation occurs under the weight of the concrete and construction loads. If the bottom of the support is a soil foundation, it should be carefully compacted, with drainage channels and a continuous timber or steel support installed to ensure that the support does not sink.
3. When assembling small steel formwork in combination, connecting components should be placed according to the specified requirements, and the spacing and specifications of the perimeter and pull-out bolts should comply with the design requirements.
4、When using prefabricated timber for beams and columns, the spacing between them must be specified and the timber must be securely fastened. The width of the timber should be slightly smaller than the cross-sectional dimensions.
5、On the beams and wall-ceiling composite panels, temporary supports must be installed to ensure the required width for concrete filling on the beams and walls.
6. When pouring concrete, ensure even and uniform distribution, strictly control the pouring height, especially on both sides of the composite panel in door and window openings. This is to ensure that the concrete is thoroughly compacted while also preventing excessive compaction that could cause the composite panel to deform.