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Posted by Lizzy Van Lysebeth on June 23rd, 2008 in └> Technical issues

In mass-producing for the furniture and interior market, High Frequency forming is a commonly used method for bending wood. Typical examples are chair seats and backs.
The following is a short 50 seconds movie of an industrial plant in Spain supplying many of the local chair and interior decoration manufactures with components

By High Frequency wood bending, wood veneers, usually between 0.5 up to 3MM thickness with glue applied (except for the outer layers) on either side, are placed in a mould and pressed into its shape. The mould’s surface emits a high frequency to rapidly set the glue between the layers.

In the short film you will see, a multi layer flat press for veneering flat board materials (ex: MDF) and for gluing the outer decorative veneers of bend components. Outer decorative veneers are often the finishing layer of a curved component. Since decorative veneers are generally more expensive than structural veneers (used for the inside structure) they come usually in thin sheets (0.5 or 0.6MM). Sanding curved components is difficult so manufactures like to sand the finishing layer before it is glued in a curved shape. Since 0.5MM is structurally too weak to pass through a speed sander it is already glued in the flat press to one structural veneer.

Applying glue to veneers or to board material that needs to be veneered happens by passing the items through 2 automatic rollers constantly soaked with glue. Often a urea-formaldehyde thermosetting 2 part adhesive is used. When the part to be moulded is larger than the size of the veneer sheets 2 or more sheets are edge glued together. Industrially this happens with a veneer Zig Zag splicer. This machine looks very much like an oversized sewing machine which glues in a zig zag motion a thread over the veneer joint holding the two veneers together.

Once glue has been applied to all the veneers they go in the press. Industrially a 2 part mould usually made out of wood or aluminium will form the curved item. The glue is set by means of high frequency transmitted by either a thin aluminium sheet covering the surface of the mould or by the mould it self if made of aluminium. Temperature will rise to +/- 120 degrees Celsius and will set the glue usually in 5 to 15 min depending on the thickness the size and the complexity of the shape. The choice for mould material depends on the production cycle. Large production will use aluminium for its durability. Smaller productions will use wood, as moulds made from wood are more economical.

Once the curve is moulded the required shape will be cut on a CNC router, a computer numerically controlled machine capable of rotating along multiple axles.

Links
Methods for bending wood

© Copyrighted by Lizzy Design
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About the author

Lizzy Van Lysebeth is a belgian furniture and interior designer living and working in London.

Before moving to London he worked with GK-Design in Tokyo and for various companies in Spain. In barcelona he was course director of a master in furniture design for an associated college to the university Ramon Llul.

In 1999 Lizzy became freelance and started Lizzy Design. In 2006 he moved to Chiswick, London were he lives with his wife and newly born son (Aug 08.)

Lizzy Design, Interior and Furniture Design
London, UK
www.lizzydesign.com

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