An integral part of printing inks is the ability to dry them, with many converters favouring UV inks because they cure almost instantly, allowing for further inline processes. There is a growing trend towards using LED light sources to cure UV inks, with most narrow web flexo press vendors now offering UV LED curing as an option for new presses. Most companies developing UV curing systems also offer retrofittable LED kits and work directly with converters to help them upgrade their presses.
A Light Emitting Diode (LED) is basically a semiconductor that produces light in the UVA range between 365 and 405 nm when connected to an electric current. The use of LEDs should lead to significant savings in running costs for converters. This is partly because the lamps use consider ably less power when they are on, and only need to be on when actually curing, leading to lower energy bills. Also, since the semi-conductor is a solid material it is not likely to break or wear out easily so the lamps last longer than mercury or metal halide lamps, with a typical life span of around 20,000 hours. Better still, LEDs can be turned on or off instantly so this should equate to several years of use. Conventional lamps, on the other hand, have much shorter life spans, which will also include the time it takes for the lamps to come up to temperature.