Why do some multi-layer parquets bend?

Multi-layer solid wood composite floor is a composite floor made of solid wood skin with a multilayer plywood as a substrate. The raw materials of the substrate and the processing technology can all lead to bending deformation of the flooring product. The deformation factors can be summarized as follows:

1, the impact of raw materials

The raw material (single board) of the base material is the same kind of tree species, the shrinkage coefficient of the wood is similar, and the base material is not easily deformed. Sometimes mixed wood is used, especially when the density of wood is different, and the wood mixing blanks with different shrinkage coefficients form an asymmetrical stress on both sides of the center layer of the substrate, causing bending or distortion of the floor substrate. Therefore, if you choose to use wood as a raw material for flooring, wood species with similar specific gravity and wood properties should be selected. Use the same tree species for the symmetrical layers on both sides of the center layer of the substrate. If conditions allow, production enterprises can sort raw materials according to tree species and wood properties.

2. Influence of moisture content of veneer

In the case where the veneer has a large moisture content distribution, for example, in the same substrate slab, the moisture content of some veneers is 7%, and the moisture content of some veneers is 14%. After the veneers are hot-pressed, The distribution of moisture content in various parts of the finished substrate sheet is not uniform, although the substrate sheet is just flat out of the press, and when the moisture content is rebalanced, bending and distortion will occur. If the moisture content of individual areas in the slab is too high, delamination can occur. Therefore, the moisture content of the veneer should be controlled within the scope of the process requirements. The veneer coating should be uniform, and the aging time can be appropriately extended to obtain a balance between the moisture content of each layer and each spot of the slab before hot pressing.

3, the impact of the internal stack (overlapping) of the substrate plate (from the seam)

Lamination inside the substrate plate will stress the plate. The effect of this stress on the entire substrate plate is not so obvious. When the substrate plate is sawn into the floor bar, the stress point will cause the floor bar to overlap. Deformed. If severe stacking occurs within the three layers of the surface, the finished lacquered floor is clearly visible in the stack (0.6 mm thick finish) during use. Therefore, it is necessary to splice the middle plate so that the middle plate can be fully sheeted, and the overlap of the middle plate can be reduced and avoided.

4, the impact of the veneer's tight surface

In the peeling process of the veneer, the elastic surface will appear. There are many cracks on the side near the cutter. We call it the loose surface, and the other surface is called the tight surface. For the same board, the tight side is the outer circle of wood, and the loose side is the side of the center of the wood. The stress generated when the tight surface expands and shrinks is greater than the loose surface. The assembly should remain tightly facing outwards and be symmetrical on both sides of the center layer of the substrate.

5. Effect of sapwood and heartwood

There is a difference in the shrinkage and expansion of wood sapwood and heartwood. In the formation of blanks, the sapwood and heartwood should be mixed as much as possible. To prevent both sides of the center layer of the substrate, one side of the sapwood side is a heartwood phenomenon.

6, the impact of the external environment on the finished product

Because the paint film on the floor surface is thick, moisture does not easily come in and out from the surface. There is less paint on the back of the floor, no continuous film is formed, and water is easy to enter and exit from the back of the floor. When the floor is packed, it is flat. If the packaging box is broken during transportation, moist air will enter, and the back of the floor will absorb moisture. After unpacking, the floor will bend towards the board surface.

In addition, many users do not immediately install the floor after opening the box, over-choose color difference, if the environment's equilibrium moisture content is higher than the floor's moisture content, the back of the floor absorbs moisture to the board surface direction, if the environment's equilibrium moisture content is lower than the floor Moisture content, the back of the floor loses moisture and bends downwards. This change is not a quality issue.

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UCT Series Bearing

Product Name	ASAHI Pillow Block Bearing UCT 205 bearing UCT205
Brand	WST / NSK / NTN / KOYO / ASAHI / OEM
Model Number	UCT205
Material	Chrome steel / Stainless Steel
Precision	P0, P6, P5, or as requested
Vibration	ZV1, ZV2, ZV3, or as requested
Clearance	C0,C2,C3, or as requested
Features	Compact structure, sensitive rotation and easy maintenance etc.
Quality standard	ISO9001:2000/ SGS
Quality Control Process	1.Assembly
	2.Windage test
	3.Cleaning
	4.Rotary test
	5.Greasing and gland
	6.Noise inspection
	7.Appearance inspection
	8.Rust prevention
	9.Product packaging
Application	Bearings for agricultural machinery, bearings for food processing and packaging, bearings for mining machinery, bearings for construction machinery