Application of particleboard in wooden door production

Topic: A brief analysis of the application of particleboard in wooden door production

Authors: Zhang Linjun1, Wang Yong2

Units: 1. Dieffenbacher Maschinenfabrik GmbH, Germany; 2. Shandong Heze Maosheng Wood Industry Co., Ltd.

Source: China Wood-Based Panels, Issue 7, 2018

Introduction

This paper mainly introduces the technical requirements and production process of particleboard for solid wood composite doors, its application in wooden door production and analysis of common quality problems.

1 Technical requirements for the production of particleboard for wooden doors

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2 Application of particleboard in wooden door production

In the production of solid wood composite doors, particleboard is mainly used for door frames, door panels and internal filling of door leaves, among which door frames and panels are the most widely used.

2.1 Production process of particleboard door frame

2.1.1 Door frame production process

Cutting particleboard → Applying solid wood edging → Drilling mortise and tenon holes → Processing mortise and tenon grooves → Assembling and forming → Thin wood veneer → Cold pressing → Length-fixing and finishing → Curing → Painting → Inspection → Packing and warehousing.

2.1.2 Door frame production process

Finishing, Maintenance, and Painting: After the door leaf is formed, it needs to be sized and trimmed to specifications. The surface is also refined, and burrs are removed from corners and chamfers. Afterwards, it is fully sanded and polished. After sanding, the primer is applied. After the primer is applied, it is usually re-sanded with a finer grit sandpaper. For higher gloss finishes, repeated sanding is required. Finally, a topcoat is applied.

2.2 Production process of particleboard door panels

2.2.1 Door panel production process

Particleboard cutting → solid wood edging → computer engraving and milling → veneer veneer → assembly and molding → cold pressing → fixed length and fine finishing → curing → painting (or PVC blister) → inspection → packaging and warehousing.

2.2.2 Door panel production process introduction

2) Paint-free door panel production process. The first half of this process is similar to the processing of solid wood composite door panels. Particleboard is cut into small panels according to the design dimensions, and solid wood strips are attached to the four edges. The panels are then milled and shaped using a computer engraving machine. The finished door panels are sized to size, and the milled grooves are polished to smooth the corners. Putty is applied in the same color as the wood grain, and sanding is required after the putty is applied. This step is repeated several times until the milled grooves are smooth and even. Adhesive is evenly sprayed on the door panels. After spraying, the surface is covered with wood-grain PVC. The panels are then vacuum-formed in a blister machine. The machine is typically set at approximately 200°C for approximately 2 minutes. The wood-grain PVC is typically 0.2 to 0.5 mm thick. After the blister is formed, the panels are trimmed and cured. Usually wood grain PVC is relatively thin, with the thinnest being around 0.1 mm. Therefore, the paint-free door panel processing technology is only suitable for panels with shallow surface milling and simple shapes, and the milling depth of the panel surface should not penetrate the surface of the particle board.

In addition, particleboard is also used as the door core filler during the production process of solid wood composite door leaves. In order to reduce the weight of the finished wooden door, hollow particleboard is often used in the door core filling. At the same time, the door cover that matches the solid wood composite door can also be made of particleboard. Relatively speaking, the door cover has lower requirements for the quality of the board, and the scraps from the door leaf processing can be rationally reused.

3 Common problems and solutions in production

1) Detachment at the frame connection. This is primarily due to insufficient tenon strength or a loose tenon joint. Generally, a tenon length of approximately 30 mm is appropriate. Too short reduces the joint area, while too long reduces strength, both of which affect joint strength. Additionally, the gap between the tenon and the mortise should be reasonable. Ideally, the diameter of the round tenon should be 0.1 mm smaller than the opening to allow for adhesive to flow into the mortise. Otherwise, the glue will be squeezed out during insertion, resulting in a "bare" joint and a loss of adhesion. When choosing a tenon, try to use one with a diagonal grain to increase bonding strength.

2) The bottom of the board is visible after finishing. One type of defect is caused by sand marks on the board surface after sanding. This defect is mainly caused by uneven sanding on the board surface. On the one hand, the sanding belt configuration during the sanding process needs to be adjusted to properly configure to reduce the deep sand marks caused by coarse sand. On the other hand, frequent inspections are required to prevent sand grains from falling off the sand belt and leaving sand marks on the board surface. If found, the sanding belt should be replaced immediately. Another type of defect is caused by stains or large shavings on the board surface. After finishing, the base color cannot be completely covered. It is necessary to select qualified panel materials and the finishing material should not be too thin.

3) Door leaf deformation. There are two main factors that cause door leaf deformation after processing and molding. First, the thickness of the veneer or PVC material used for the blister packaging is inconsistent on both surfaces. Therefore, when processing the door leaf, try to use veneer materials from the same batch and type. Second, insufficient curing time can also cause door leaf deformation. Generally, after cold pressing or blister packaging, the door leaf needs to be stacked horizontally for at least 24 hours to fully eliminate internal stress.

4) The finishing layer is bulging or falling off. Such defects are generally caused by uneven spraying of the adhesive or the failure of the adhesive. Therefore, during the processing, the adhesive must be evenly applied to the entire bonding surface. Each time the adhesive is mixed, it is best to use it all at once. At the same time, during the storage process, the adhesive should be kept away from direct contact with air for a long time.

4 Conclusion

As living standards improve, consumers' perceptions of wooden doors are shifting. They no longer simply serve to insulate spaces and protect against cold weather. Consumers now demand more from wooden doors in terms of design, functionality, and fashion. With further tightening of real estate regulations, competition in the wooden door market is expected to intensify. Coupled with rising raw material prices and a restrictive external environment, wooden door manufacturers are bound to form closer ties with upstream wood-based panel manufacturers. Only by grasping customer needs, providing products that meet their needs, and jointly innovating and developing can we lead the way in future market competition.