The lifespan of UV mercury lamps is somewhat limited, and the irradiance of the lamp will gradually decrease. The UV lamp manual mostly indicates that it must be replaced after about 1000 hours of use. Before the service life of UV mercury lamps reaches its limit, it will cause a decrease in ink curing performance, and excessively aged lamps cannot dry UV ink or varnish well. In actual production, if you feel that the printed material cannot be dried at normal printing speed, you must consider replacing the UV mercury lamp.
If a reflector is not installed, approximately 80% of UV light will be diffused and unable to reach the printed material. Therefore, UV mercury lamps must be equipped with lampshades to reflect and focus on the direction of the substrate. At the same time, the reflector must be cleaned and maintained at all times. If substrate debris or dust adheres to the reflector, it will affect the irradiance of the UV mercury lamp; If the UV mercury lamp is not used for a long time, the UV lampshade should be closed to prevent dust from entering.
Due to the temperature rise of UV mercury lamps during irradiation, plastic film substrates can be deformed by heat, resulting in inaccurate overprinting.
In recent years, LED UV lamps have begun to be applied in the field of flexographic printing. LEDUV lamps are called "cold light sources" because the lamp surface does not generate heat during operation (of course, this does not mean that the entire working process does not generate heat). According to research, the photoelectric conversion efficiency of LEDUV lamps is about 30%, and the remaining 70% of the electrical energy is converted into heat, which is dissipated from the back of the lamp board. Therefore, LEDUV lamps and other devices also need to be equipped with a water cooler for 70% of the light source's electrical power to dissipate heat from the lamp head.
