Keep It Cool to Keep It Clean

Advantages of UV LEDs when coating heat-sensitive types of wood

UV LED lamps provide much cooler curing than traditional UV lamps. This is particularly useful when curing heat-sensitive substrates such as glued veneers and resinous woods such as pine. The narrow UV-A wavelength output of UV LEDs presents some formulating challenges. Some solutions are proposed and curing temperature comparisons presented.

The benefits of UV LED as compared to traditional UV lamps are numerous and significant for wood coating operations.

Light-emitting diodes for ultraviolet curing applications, UV LEDs, have been commercially available for a decade now. However, their unique output characteristics work best with newly formulated UV chemistries that take advantage of the many benefits of UV LEDs. Initially, UV LEDs were used in applications such as medical device assembly and inkjet printing, but their increasing energy outputs and lower initial costs mean that wood coating applications have become commercially viable. Coating heat-sensitive wood substrates is especially challenging, but recent testing shows that UV LEDs provides a significant advantage over traditional UV lamps. The characteristics and benefits of UV LED lamps are considered and compared to traditional UV lamps for wood coating applications, including recent temperature test comparisons, and formulating strategies for optimising the performance of UV LED systems are reviewed.

The benefits of UV LED as compared to traditional UV lamps are numerous and significant for wood coating operations. UV LEDs are more environmentally friendly because, unlike traditional lamps, they do not generate ozone and contain no mercury.

The electrical to optical conversion efficiency of UV LEDs is also much better, while the instant on/off and elimination of warm-up time results in combined savings of 60 % on electricity.

They are a cool source compared to arc lamps, largely due to the absence of output in the infrared range. This reduced heat eliminates complicated cooling mechanisms such as cooling air (quieter operation) and external shutters, and permits applications on heat-sensitive wood substrates such as glued veneers and resinous woods. 

Compared to a traditional lamp’s 500 - 2,000 hour life, most UV LEDs are specified for 10,000 hours, but can last 20,000 hours or more. It is also important to note that over this lifetime, UV LED output only drops by about 5 %, as compared to traditional lamps which lose about 50 % of initial output by the end of their life. In a wood coating production environment, UV LEDs require significantly less space, monitoring, maintenance and down-time, which translates into higher productivity rates, less scrap and higher quality end products at lower costs. Paybacks for retrofitting onto existing machines or replacing existing UV lamps can be as low as 12 months.