The new bending technique consists of heating and plasticizing large and long planks of sawn and planed wood, and thereafter compressing them in the direction of the fibres to about 80% of the original length. When the pressure is released, the wet plank expands towards its original dimension, but there is a permanent length reduction of about 5%, and seen in a microscope all axial fibres have folded walls, just like the folds in a concertina. Compressed wood can be bent either hot or cold and in most cases without the use of a strap. After drying and conditioning, compressed wood has about the same strength properties as traditional steam-bent wood, and the wood can be machined without difficulty. After drying and conditioning, compressed wood has about the same strength properties as traditional steam-bent wood, and the wood can be machined without difficulty.
Some of the advantages of preparing wood planks for cold bending are summarized below:
- Bending solid hardwood in small radii of curve and in several planes presents a powerful technique for new designs and future product development.
- The wastage rate is rather law. Up to 35-40% higher yield can be gained compared to traditional techniques of shaping wood. This fact, combined with a remarkable higher quality of the finished product, leads to lower production costs and better sales prices of the finished products.
- It is an ecological technology compared to form bending as no chemicals or glue is used.
- Possibility of storage of the compressed planks for "just in time" production enables a rational production planning, faster response time and less stock value.
For more information please visit Bendwood Engineering’s website