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UV Inkjet Maintenance

(December 2011) posted on Wed Jan 25, 2012

Taking care of your printer’s curing system is neither difficult nor time consuming, but proper monitoring and maintenance must be priorities if you want to realize the full benefits of this technology.

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By Screen Printing's Solution Sourcebook

UV-LED units, a newer breed of curing technology, are engineered for low-temperature curing and, therefore, can accommodate a variety of heat-sensitive materials that might be affected by conventional UV curing. Many on-board UV-LED curing units are rated at 10,000 hours or more of useful life.
UV curing systems deliver an optimum dose to printed substrates for a certain amount of time, after which the dose declines. Deterioration can occur very gradually, giving the impression, for example, that a 1000-hour-old lamp is functioning correctly. A dirty lens also reduces the dose delivered to the substrate’s surface.

Lamps will ultimately fail if they’re not replaced (Figure 1). Detecting a decline in curing-system performance before total lamp failure can be as simple as handling cured prints. The feel of the cured, printed surface will change when lamps start to reach the end of their usefulness. Those who want a more objective method of measuring curing-system performance can use a radiometer or, for inkjet systems that cannot accommodate probes between the printhead assembly and substrate path, an adhesive-backed label that reacts to UV exposure by changing color (Figure 2). These labels can be affixed to substrates and run through the printer at various stages of lamp life, beginning when lamps are new and repeated periodically thereafter until lamp output becomes unsuitable.

Quantifying lamp output may be unnecessary if you simply monitor hours of lamp operation and stick to the manufacturer’s lamp-replacement guidelines. But you still need to take steps to optimize lamp life. One way is to make sure the lamps are idle when the printer is not in use. The printer’s operating software, which allows you to vary curing-lamp intensity to best match the substrate with which you’re working, may enable you to select the time of inactivity that must elapse before the printer automatically powers down its curing system. Precise workflow management is another way to make lamps last longer. Keeping the lamps powered up and in use once they’re activated can be more effective in terms of longevity than switching them on and off throughout the day. Queuing jobs in the RIP so that the printer is feed jobs constantly can help.


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