LED - Light Emitting Diodes

• Semiconductor (diode), which emits light, when electric current flows throughout in forward current. As result the diode radiates light, infrared radiation or also short-wave ultraviolet radiation in a relatively narrow emitter zone, dependent on semiconductor material and doping.

Purpose 1: visible light

• Signalling units for the positioning of for example suction cups in CNC-machining centres
• Example: LED luminous tape

Purpose 2: UV radiation - Tempering of coatings

The first concepts for the use of LED technology in the surface coating of wood were developed by the company Bürkle in 2008. Meanwhile, many manufacturers that are active in the area of surface finishing offer UV-LED-systems.

Hybrid-Versionen

'Hybrid version' means a combination of LED radiation sources and conventional mercury and gallium lamps.

Essential advantages of the LED technology in the area of wooden surfaces in comparison with conventional UV technology with for example mercury and gallium lamps:

• significant reduction of the energy consumption,
• lower thermal load of the workpieces and the coating material,
• substantially longer life of the LED lamps,
• no emergence of ozon,
• no continuous air exhaust (considerably lower cooling requirements).
• examples: Bürkle, Cefla, Venjakob

It is obvious that manufacturers put much effort into the reduction of current limitations of application concerning the LED technology and thus try to enable new usage areas. However, the two areas adhesive processing and digital print are regarded as established. It is assumed that further application areas will follow, where the UV-LEDs can completely unfold their specific advantages (nearly monochromatic, low reactions timelow temperature).