Application of particleboard in wooden door production

Title: A Brief Analysis of the Application of Particleboard in Wooden Door Production

Authors: Zhang Linjun1, Wang Yong2

Companies: 1. Dieffenbacher 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 wood door production, and an 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 frame, door panel, and internal filling, with the door frame and panel being the most widely used.

2.1 Particleboard Door Frame Manufacturing Process

2.1.1 Door frame manufacturing process

Particleboard cutting → Applying solid wood edging → Cutting mortise and tenon joints → Processing tenon grooves → Assembling and shaping → Thin wood veneer → Cold pressing → Length finishing → Curing → Painting → Inspection → Packaging and warehousing.

2.1.2 Door frame manufacturing process

Finishing, curing, and painting: After the door panel is formed, it needs to be measured to the required dimensions, and the surface finish needs to be finished, removing burrs from the edges and chamfers. Then, it is thoroughly sanded and polished. After sanding, the primer is sprayed. Generally, after the primer is sprayed, it needs to be sanded again with finer sandpaper. For higher gloss, it needs to be sanded repeatedly. Finally, the topcoat is sprayed.

2.2 Particleboard Door Panel Manufacturing Process

2.2.1 Door panel manufacturing process

Particleboard cutting → Applying solid wood edging → Computer-aided carving and milling → Thin wood veneer → Assembly and shaping → Cold pressing → Length finishing → Curing → Painting (or PVC vacuum forming) → Inspection → Packaging and warehousing.

2.2.2 Introduction to Door Panel Manufacturing Process

2) Paint-free door panel production process. The first part of this process is similar to that of solid wood composite door panels. Particleboard is cut into small boards according to the design dimensions, and solid wood strips are attached to the four sides. Then, the shape is created using a computer-controlled engraving machine. The shaped door panel is then sized and cut to size. The milled grooves are sanded to make the edges smoother, and putty matching the wood grain color is applied. After applying the putty, it is sanded again. This process is repeated multiple times until the milled grooves are smooth and flat. Adhesive is evenly sprayed onto the door panel surface. After the adhesive is applied, wood grain PVC is covered on the surface, and the panel is then vacuum-formed in a vacuum forming machine. The vacuum forming machine temperature is generally set at approximately 200℃ for about 2 minutes. The wood grain PVC thickness is generally 0.2–0.5 mm. After vacuum forming, the edges are trimmed and cured. Wood grain PVC is usually quite thin, with the thinnest being around 0.1 mm. Therefore, the processing technology for paint-free door panels is only suitable for panels with shallow surface milling and simple shapes, and the milling depth of the panel surface should be such that it does not penetrate the particleboard surface.

In addition, particleboard is also used as a core filler in the production process of solid wood composite doors. To reduce the weight of the finished wooden door, hollow particleboard is used more often for the core filling. At the same time, the door frames that match solid wood composite doors can also be made of particleboard. Relatively speaking, the quality requirements for door frames are lower, and the scraps from the door processing can be reused.

3 Common problems and solutions in production

1) The frame joints are coming detached. The main reason is insufficient tenon strength or an unsecured tenon joint. Generally, the tenon length at the joint should be around 30 mm. If it is too short, the joint area will be smaller; if it is too long, the strength of the tenon will decrease, both affecting the splicing strength. In addition, the gap between the tenon and the mortise should be reasonable. Theoretically, the diameter of the round tenon should be 0.1 mm smaller than the hole to allow space for the adhesive to flow into the mortise. Otherwise, when the round tenon is inserted, the glue will be squeezed out, becoming a "bare rod" and losing its adhesive strength. At the same time, when choosing tenons, try to use tenons with a grained surface to increase the bonding strength.

2) Showing through after finishing. One type is caused by sanding marks on the board surface after sanding. This type of defect is mainly caused by uneven sanding of the board surface. On the one hand, it is necessary to adjust the sanding belt configuration in the sanding process, and reasonably configure it to reduce the deep sanding marks caused by coarse sand. On the other hand, it is necessary to check frequently to prevent sand particles from falling off the sanding belt and leaving sanding marks on the board surface. If any are found, the sanding belt should be replaced in time. Another type is caused by stains or large wood 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 used should not be too thin.

3) Door panel deformation. There are two main factors that cause door panel deformation after processing. First, the thickness of the veneer wood or vacuum-formed PVC material on the two surfaces is inconsistent. Therefore, when processing door panels, try to use veneer materials of the same batch and model. Second, insufficient curing time can also lead to door panel deformation. Generally, after cold pressing or vacuum forming, door panels need to be stacked horizontally for curing for more than 24 hours to fully eliminate internal stress.

4) Blistering or peeling of the finish layer. Such defects are usually caused by uneven application of the adhesive or adhesive failure. Therefore, during the processing, the adhesive should be applied evenly to the entire bonding surface. Each batch of prepared adhesive should be used up at once, and the adhesive should be kept away from direct contact with air for extended periods during storage.

4. Conclusion

As people's living standards improve, consumers' perceptions of wooden doors are changing. Wooden doors are no longer simply used for isolating spaces and providing insulation; people have higher demands for design style, functionality, and fashion. With further tightening of real estate regulations, competition in the future wooden door market will become increasingly fierce. Coupled with rising raw material prices and external constraints, wooden door manufacturers will inevitably work more closely with upstream engineered wood panel companies. Only by grasping customer needs, providing products that meet those needs, and jointly innovating and developing can they lead the trend in future market competition.