Substrate Cooling
The UV curing process is energy-intensive and causes both direct and indirect heating of the target substrate, which in the majority of cases needs to be controlled. For safety reasons, some form of barrier behind the target substrate to shield off and dissipate stray radiation from the lamp is essential for protecting the machine and its operators. The three most common methods of substrate cooling that meet both of these requirements are:
Air cooled heatsinks
Water cooled heatsinks
Water cooled chill rollers
Where roll material is being processed, the most common solution for this is an extruded aluminium heatsink plate. GEW have a very neat solution for this which is integral to the UV lamphead and can be either air or water cooled, depending on the application. For the majority of processes this method is very effective, unless very heat sensitive materials are being used.
Other Products and Services from GEW (EC) Ltd
UV LED Lab Unit
GEW’s LED lab unit utilises a high precision linear drive to pass a sample tray under the UV LED array.
Variable speed control ensures highly repeatable testing up to 100m/min with UV power adjustable in set increments and LED array height adjustable up to 25mm.
A simple magnetic hinged tray carries print samples or can accommodate an EIT radiometer for precise UV power measurement.
ExciRay Lamps
GEW’s ExciRay lamp systems utilise dielectric barrier discharge (DBD) lamps to produce quasi-monochromatic vacuum ultraviolet radiation, typically at 172nm. This radiation is commonly used for mattification of surface coatings, modification of surface tension for improved adhesion or surface cleaning for semiconductor and medical industries.
GEW ExciRay lamps, which are incorporated into the familiar NUVA2 cassette design, can be produced up to 255cm in length and can be custom integrated for your specific application, including provision for all required nitrogen inerting and control.
DoseGuard
DoseGuard consists of a scanning optic (ICAD® unit) mounted underneath the lamp, which continuously measures the UV light that reaches the substrate, across the entire width of the system. It improves the UV curing process by automatically adjusting the power of your GEW UV lamps to maintain a target UV dose.
DoseGuard can be set to scan each UV lamp or LED array individually, reporting any imperfections in UV output across the entire width.
Benefits of DoseGuard
- Perfect UV output control: DoseGuard monitors the UV output of any UV lamp or LED across its entire width, and will issue a warning if the level of UV output delivered to the substrate changes during production, for any reason.
- Guaranteed product quality and reduced waste: Automatic dose control ensures your product is cured to exactly the correct level by adjusting UV output of each lamp to maintain the same UV dose delivered to the product, independent of speed or UV lamp condition, even for multiple lamps on a single print / coating station.
- Reduced energy and maintenance costs: Only use the exact power required to achieve good quality product by automatically optimising lamp power to deliver desired UV dose. This feature also increases lamp lifetimes and enables bulbs and reflectors to be used for longer.
- Documentation for compliance or GMP: Operational data can be exported via a software connection to the controller, or via ModBus protocol so that compliance documents or certificates of compliance can be generated by the customer.
Full Width UV Output Monitoring
The calibrated ICAD® radiometers are mounted beneath the UV lamp and measure irradiance at the focal point of the UV lamp, across its entire width.
They scan the whole UV lamp and measure changes in UV output from lamps and reflectors, but also detect spot contamination or degradation with age.
Operators can set a ‘window of acceptance’ and ICAD® can send warnings when output decreases below set values. The frequency of checks can also be adjusted.
When static, ICAD® radiometers park in a protected position away from contaminants and the substrate. Scan passes are very fast, thus avoiding any shadowing impact.
DoseGuard with ICAD® inside, enables inline and automated power level adjustment for a uniform and specific power distribution over the full length of the UV lamp or LED. It offers the benefit of continuous monitoring during production which increases quality, uptime and reduces the risk of producing waste.
Example: ink stain on quartz window reduces UV dose by 48% under the contaminated area – this cannot be detected by online static sensors.
GEW (EC) Ltd
Crompton Way, Crawley, West Sussex, RH10 9QR, United Kingdom
GEW (EC) Ltd designs and manufactures Arc and UV LED curing systems for printing, coating and converting applications. GEW is the leading manufacturer of UV curing systems for a range of markets, including narrow web label printing, offset printing, UV hot melt, wood coating and much more.