Today Solid Wood Bending is a production technology, that is mainly used in two areas:
- Sleighs & Toboggans
Both applications support the natural properties of bentwood in a positive way:
- No interference of the fibre flow, the high impact resistance and fracture toughness remains.
- The positive relation between strength and mass is even more supported by the small cross-sections that are necessary.
Bending wood is relatively simple: hardwood with approx. 16 – 20% moisture content is softened for bending in predefined dimensions plus a little excess by the application of saturated steam in a steaming cylinder. The steaming time depends on the species, moisture content and thickness of the wood. The steamed wood is placed in a strap of the same length, then immediately inserted in the bending machine to be bent around the mould fixed to the bending machine. A clamp is placed over the ends of the strap the machine returned to its starting position and the strap removed from the machine together with the wood and the clamp. The bending process takes approx. 20 – 40s. Depending on the width, several parts can be bent simultaneously. After bending, the parts are kept in the strap for 60 – 90 minutes, then dried (air / technical).
A simple bent-shop has a compact steamer for softening the wood, a Solid Wood Bending Machine, some molds, straps and hooks.
Besides a steam generator or a steam converter, a fully equipped bent-shop has a number of autoclaves, two or more bending machines, a cooling belt, a device to open the clamps, and some frames to fix bent parts to dry free from distortion.
With all necessary accessories a solid wood bending machine can produce all bent parts for approx. 5.000 chairs per week (one shift operation, 8 h per day).