UV inkjet lamp life
Jeremy, in the shop, would be able to answer that better, but we pretty much run them near full blast regardless. The only thing we've noticed is the blues will stop drying faster than any other color, giving you the felling, there's a problem with the cyan ink, since all the other colors are performing fine. We generally just change out both bulbs, save them with how many hours are on them, left & right and put them in a safe spot, just in case something happens down the road and we need a bulb faster than our supplier can get it to us. There's always some life left in them, just not enough for a few days worth of pure blue printing.
In the case of digital inkjet lamps, life depends on many factors including number of starts, thermal operating conditions, power rating and proper handling.
Most inkjet printers estimate UV lamp life around 500 hours (idol time plus print time). To reach this goal they suggest operating the lamps at lower power for the first 300 hours and gradually increasing power as the lamp ages. Simply defined, it is the hours the lamp produces enough UV energy to properly cure the ink within the available exposure time.
Ink color and opacity have much to do with ability to cure. Deep blue or heavy laydown black inks almost always require full power operation. If adhesion problems are UV intensity related, then increasing lamp power will increase the ink’s bond with the substrate. This is especially true when printing more than one coat. In this case the first printed layer must be fully cured before subsequent coats are applied. Adjust combination of lamp power and print speed. In a perfect world, ink and media bond is improved at high lamp power and slow print speed. Consider uni-directional printing over bi-directional. Since this is not a perfect world, this combination produces the highest amount of heat perhaps adversely affecting (warping) the substrate. Some printers offer an option of UV exposure without printing. This allows for lower temperature multiple exposures.
To extend lamp life clean reflectors, quartz plates and air filters regularly. Most ultraviolet lamps are air cooled hence they must live with whatever air is provided. Lamps must be kept clean. All types of dust, powder, grease, smoke and misting ink must be cleaned from lamp. Often shop contaminants will blow over the lamp sticking to the quartz literally baking onto the surface. This reduces UV energy and may cause bulb overheating. The same holds true with reflectors, and quartz plates (if used). Use a lint free cloth with Windex or Simple Green to clean. Don’t waste your money on special UV lamp cleaners as they have dubious value! If solvents are permitted, use isopropyl alcohol. For extreme cases use a mild abrasive such as Soft Scrub to clean the UV lamp. Be sure to rinse any residue off the glass before reinstalling lamp. Consider replacing quartz filter plate (available from the OEM or TCS Technologies) to maximize UV performance.
To reduce gloss banding and maintain equal UV dosage when printing bidirectionally, it is recommended that both UV lamps be replaced at the same time.
Lastly do not overlook shutter operation. Most inkjet dryers incorporate shutters that close when lamp is not printing. Make absolutely sure the lamp assembly shutters are opening completely. On more than one occasion we have seen screws come loose preventing the shutter from opening.
The key to extending lamp life is having a high output lamp mounted in a clean fully operating UV system.
