UV Curing Equipment
UV or Light curing lamps are available in three basic types, Spot Lamps, Flood Lamps and conveyors.
The light sources can be Bulb or LED lamps.
Bulb lamps normally emit a broad range of wavelengths predominantly in the UV A and Blue spectrum while the new LED lamps have a very narrow spectrum around a specified wavelength. In selecting a UV lamp it is important to match the wavelengths emitted with the material to be cured. Bulb lamps degrade significantly over their specified life which is normally around 2000 hours. Also these lamps have warm up times of around 5 minutes and will not restart for a similar time.
Hence they are normally left on for the full working period. By contrast LED lamps have stated lives ranging from 20,000 to 50,000 hours and as they give instant output are only switch on for the time required for curing.
As bulb UV lamps and lightguides degrade it is important to be able to measure the light intensity reaching the adhesive. The ACCU-CAL range of radiometers enable light intensities to be measured at the source and at the end of the lightguide.
Spot lamps
These lamps give a spot between 3mm and 8mm in diameter of high intensity at the end of a lightguide.
The intensity can be between 3000 and 20,000 nW/cm2. In the case of bulb lamps a mechanical shutter is used to control the output while LED lamps are direct electrical operation. Lightguides can be supplied to split the output into upto 4 spots.
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Flood Lamps
Dymax have three sizes of flood lamps, they all use the same power supplies and bulbs but disperse the light in different ways. The 2000 and 5000 models cover 200mm or 125mm square while the 1200 model focuses the light into a 25mm wide strip 125mm wide. The wider the coverage the lower the intensity.
The normal halide bulb supplied is best for the UVA range but mercury bulbs can be supplied for ink curing.
A range of shielding and shuttering options are available to suit these lamps.
Conveyor Systems
For higher volume production applications conveyor systems are used with a variable speed driver that carries the work piece through a tunnel to be exposed to the UV lamps These may use any of the flood lamps or the higher intensity Fusion Lamps. The basic conveyor unit has a 300mm wide belt and may be equipped with a combination of lamps . The side cure system has lamps facing horizontally while the edge carry unit does not have a belt but supports the work on the edges.
Radiometers
The intensity of light sources is measured in mW/cm2for specific wavelengths.
Radiometers are used to measure both intensity and dosages.
As bulb lamps degrade over their life it is important to monitor the output intensity to ensure full cure. F or spot lamps it is also important to measure the light loss in the lighguide as these also degrade with use and damage.