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The lamp is the heart of a UV curing system. Important not to forget, as the complete performance of your application depends on this. On this page short about; UV Output, Lamp-types, Lifetime and Choice of lamp type.

The output from a mercury lamp is divided into Heat and UV. The amount of heat is app. 70% and UV the rest - 30%. The useful UV is again divided into three areas - UV-A 315-380Nm, UV-B 280-315 Nm and UV-C 200-280 Nm. Normally UV is the "curing power", but on some older colours and special applications, heat or higher wavelength (moving up from UV-C>B>A) is required. But just like the design of the mechanical system is determined by your application, so is the choice of lamp-type.

Different lamp types are merely Mercury lamps doped with different materials, giving very different UV output. In Europe the most common used lamp type is a standard Mercury. If you go to the far east it is an Iron doped Mercury lamp. They both have the same amount in UV output, but the Mercury has more energy in the low UV range (UV-C). Other types can be used, normally for more specific applications and often as advice from the ink/lamp manufacturer.

The lifetime of a lamp is determined by use. A standard Mercury lamp loses 30% of UV energy after 2000 hours, an Iron doped last only 8-900 hours, because of decomposition of the Iron. Lamp lifetime is also determined by how many times it is ignited, as the small particles from electrodes will contaminate the inside of the lamp, which eventually will fail to ignite. Use of high frequency power supply will extend the lifetime, as the particles tend to stay (on the inside of the quartz) near the electrodes.

It is seen that the difference in UV output is in the UV-C region. The energy from the UV-C region has moved up in UV-B and UV-A, on the Iron doped lamp.

As the UV-C is difficult to handle, easy to loose energy in reflection and in air, the choice of an Iron doped lamp can be an advantage.

 

For further information: Contact         For further information on lamp types: http://www.alpha-cure.com/metal-halide-lamps.htm 


The reason of choice:

Choice of lamp depend also on your UV system. On poor UV systems the most common reason for lamp exchange are two things. To narrow curing width, caused by "black ends" - particles from ignition, and secondly the cooling-air in non-water system will contaminate the surface of the lamp, blocking out the UV light. In some cases the loss of UV can be 20-30%, after 300 hours of use. The typical colour thickness will also effect your choice - as UV-C cures in the toplayer, the longer wave lengths UV-B/A, penetrates down into thick layers.

So the choice can be made from your UV system and your colour. An older Transformer system, using unfiltered air, would probably gain from using for example an Iron Doped Lamp as the lifetime will be short in any case. A new closed system with clean filters, or water cooled, will have a much longer lifetime, using a standard Mercury Lamp. But again your Ink/varnish and thickness might require a special lamp type.

 


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