Based on the company’s retractable cassette system, this third-generation reflector cartridge arrives as a replacement to the existing XC extreme cure reflector system used on its VCP and eCP product platforms.
GEW says that the reflector profiles were designed using ray-tracing, a computerised modelling program to simulate the effects of different reflector geometries and to make the most of the amount of UV energy reaching the ink. It says this enables the latest reflectors to be in the region of 25-30 per cent more efficient and that heat management capabilities have also improved. It names three key design improvements:
First, the reflector material now made consists of a specially developed, multi-layered dichroic coating as opposed to the polished aluminium used before. This allows the infra-red radiation from the lamp to be absorbed by the reflector and removed by air-cooling of the reflector’s rear surface; UV radiation is simultaneously re-directed back to the web. The dichroic coating itself is applied to replaceable reflector inserts as opposed to directly onto the extruded reflector body. GEW says this makes them cheaper to replace should they become scratched or dirty.
Second, the addition of a cold filter blocks IR radiation from the lamp and prevents it from reaching the printed substrate, whilst allowing the UV to pass through.
Thirdly, a the integration of a cold shutter, which GEW says has eliminated the risk of damage to substrates from heat when the press stops and the shutters close. The single-blade shutter is parked away from the direct radiation path of the lamp when the UV is running, so when the machine stops and it closes, it is cool. A layer of thermal insulation also covers the exterior of the shutter in case the lamps are left on stand-by for a long period of time, which prevents any heat absorbed by the shutter from being re-radiated to the web. When the press re-starts, the shutter opens and moves into its parked position, where it is re-cooled by the lamphead’s internal airflow.
