Common Quality Problems of Building film faced plywood and Solutions

 

Common Quality Problems of Building film faced plywood and Solutions

 

Installation and use of film faced plywood is an important part of modern building construction. Installation quality and efficiency have a great influence on concrete quality and performance, and have a direct relationship with the whole building quality and performance, so its importance need not be said much.

 

Tools/raw materials

 

Common quality problems of film faced plywood include many reasons of production process, but besides production process, manual maintenance also has a great impact on the quality of film faced plywood.

 

It is very important to choose a good film faced plywood, such as medium iron green super-strong composite film faced plywood, film faced plywood core vertical structure, board surface polymer waterless fiber, high strength, impact resistance, wear resistance, long service life, high turnover rate.

Common problems: weak adhesive, large area degumming

 

Reasons: 1. The quality of colloid is not good (such as mildew), 2. The moisture content is too high.

Solutions: 1. Because of the large area, it is not easy to repair. Tear the veneer off, scrape off the residue and re-paste. 2. When the veneer is over-pasted, the moisture content of veneer should be controlled at 12%-14%.

Common problems: local degumming and bubbling

Reasons: 1. No glue was applied locally. 2. The hot pressing time is too long. The glue has been coked. 3. The moisture content is not uniform.

Solutions: 1. Overglue and hot pressing should be uniform; 2. Use sharp cutters to cut the thin wood along the wood grain or inject the glue into the bubbles with a thick-headed syringe, and then press it flat with an iron; when the bubbling area is large, remove the veneer, scrape the residual glue, re-glue the adjacent veneer, tighten the periphery of the patch; 3. Veneer or the core of the veneer. The water content should be uniform.

 

Common problems: the surface of the adhesive is uneven

Reasons: 1. The surface of the base material itself is uneven; 2. The thickness of the rubber layer is uneven, and the excess glue is not extruded during hot pressing.

Solutions: 1. It is difficult to repair. In serious cases, the veneer can be planed off again and the surface of the parts can be repaired. 2. Extrude the surplus glue to form a thick and uniform glue layer during hot pressing.

 

Frequently asked questions: there is a permeability on the surface of the adhesive

Reasons: 1. The glue is too thin and the glue amount is too large; 2. The veneer thickness is not up to the standard; 3. The veneer structure causes (the duct is too big); 4. The veneer moisture content is too high; 5. The unit pressure of the glue is too high.

Solutions: 1. Adjust the viscosity and amount of adhesives, the weight ratio of adhesives is based on the principle of PVAc + flour > UF; 2. Use thin wood with a thickness of more than 0.6 mm to avoid penetration; 3. Select trees with smaller ducts; 4. Veneer moisture content should not be too high; after wet cloth rubbed, it should be pasted naturally and sprayed less before hot pressing; 5. Extend ageing. The unit pressure should be controlled between 0.5 MPa6 and 1.0 MPa6, slightly scraped or abraded with a knife, and severely removed and re-pasted veneers.

 

Common problems: cracks on the adhesive surface

Reasons: 1. improper mix ratio of adhesives; 2. excessive hot pressing temperature and pressure; 3. veneer thickness is too thin and poor quality; 4. veneer moisture content is too high, shrinkage after drying 5. There are problems with the quality of base material.

Solutions: 1. Adjust the mix ratio of adhesives (increase UF, use curing agent) and improve the water resistance of glue; 2. Reduce the temperature and pressure of hot pressing properly, spray water after pressure relief and stack the film faced plywoods face to face after hot pressing to reduce water evaporation; 3. Use slightly thick thin wood or sandwich buffer layer (a layer of paper) between thin wood and base material, and inject. The texture direction of paste; 4. The moisture content of veneer should not be too high; 5. Choose the suitable base material.

Frequent problems: the surface of the adhesive is contaminated

Cause: Wood itself contains oils, lipids, waxes, tannins and pigments.

Solutions: Resin and oil stains can be erased with alcohol, ether, benzene and acetone, or with 1% caustic sodium or sodium carbonate and then with clean water. Pollution caused by tannin, pigments and iron ions can be erased with hydrogen peroxide or 5% oxalic acid.

Common problems: black glue seam, off seam or lap seam in jointing

Reasons: 1. Insufficient cutting knife when matching film faced plywood results in incomplete and rigid jointing; 2. High moisture content of thin wood and drying shrinkage; 3. improper glue viscosity.

Solutions: 1. Cutter must be sharp; veneer should be as tight as possible when gluing, but the central part should not be tightened or lapped; 2. Veneer moisture content should be controlled, not too high, water can be sprayed at the joint; 3. Adjust adhesive viscosity (increase UF) and glue amount; 4. Reduce hot-pressing temperature.

Common problems: film faced plywood surface warping deformation

Reasons: 1. improper mix ratio of adhesives; 2. improper hot pressing conditions; 3. unsymmetrical veneer on the back of the surface; 4. high moisture content and drying shrinkage of veneer

 

Solutions: 1. Reduce the ratio of UF glue to make the glue layer soft 2. Ease the hot pressing conditions. After hot pressing, stack and press the weight block horizontally. The veneer used for surface and back gluing should conform to the symmetry principle and pay attention to the texture direction of the glue 4. The moisture content of veneer should not be too high.

Frequent problems: the bottom color of the board surface

Reasons: 1. Veneer thickness is too thin; 2. Uneven tone of base material

Solutions: 1. Stick a slightly thick veneer or paper with the same color as veneer on the base material; 2. Coloring the base material or adding a small amount of colorant in the adhesive.

Common problem: indentation on the surface

Cause: There are impurities on the surface of veneer or glue marks on the surface of substrate, etc.

Solution: The sundries on the veneer surface should be removed in time, and the veneer surface should be kept clean.

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