Plytec technology ensures a maximum yield from short and thin timber. Scarf jointing allows the veneer to be lengthened into sheets of the required size, so that the dimensions of the plywood panel no longer depend on the individual dimensions of each log used. Plytec’s scarf-jointing system is basically the only cost-effective way to make plywood out of small diameter logs.
Scarf jointing is a simple process, but when quality is essential, the production process must be stable and easy to control. Firstly, a unit peels the veneer sheets along the grain; secondly, glue is applied to the topmost bevel; and finally the sheets are pressed together. The Plytec system ensures that the scarf jointed veneer matches the strength of adjacent material. The Plytec Scarf Jointing System is based on thoroughly tested and proven technology that is highly adaptable and provides a large spectrum of solutions. By tailoring it to individual customers’ needs, Plytec ensures maximal productivity and scalability of the system to meet any future requirements. For example, the system can be set up so that more pressing units or automatic control systems can be added as production increases or as quality demands grow.
As strong as any veneer
In scarf jointing, both ends of the veneer sheet are bevelled by a scarfing saw, so that one is on the top surface and the other on the bottom. Jointing glue is then applied to the topmost bevel. Next, the bevelled and glued veneer edges are positioned one above the other and pressed together in the jointing press. This happens under a very precise pressure and temperature, so that the end result is an seamless veneer mat that runs in the same grain as the veneer. The veneer sheet is then clipped to the required length by the clipper in the pressing machine.
The width of the veneer sheet depends the width of the peeling (or drying) line at the point of the clipper. In cross-grain plywood, the scarf-jointed sheets are used as glue veneers. In long grain panels, they are used as both dry core veneers and face/back veneers. In the first case, scarf-jointed veneer can fulfill any criteria required; and in the second it works just as well as regular long grain veneer. In technical use as a face/back veneer, scarf jointed veneer is as good as any long grain veneer. This means that the scarf-jointed surface can be overlaid with a thin decorative skin that will give the required finish to a panel. One should also bear in mind that with many technical plywood panels there are no visual requirements for the face, which means that scarf-jointed surfaces would be perfectly suitable.
• Larger freedom in raw material purchases through higher adaptability to varying raw material dimensions
• Increased ability to respond to varying demands in plywood panel size
• Easier production management increases productivity
• Improved veneer recovery means more money with every scarf joint
• Top-quality products in spite of raw material timber size and shape
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