Bron Wolff discusses how you can assess and improve your UV-dryer performance by learning from his company's experience.
By Bron Wolff
Since those early experiments, we have gone through this process with every lamp and every UV dryer in the plant. As mentioned previously, it has taken several years for us to achieve successful results. The smaller diameter lamps we now use outperform the thicker lamps we used the past by delivering higher irradiance to our prints. The small diameter gives the lamp less surface area, which means there is less quartz to absorb the energy and convert it to heat. We can run these modified lamps at nearly double the power level (wattage) of the standard, large-diameter lamps before we even begin to approach the heat levels generated by the larger lamps.
On one of our inline printing systems, we have gone through six different generations of modified lamps. But the effort has paid off in effective and efficient curing with no heat-related damage on any of the materials we print, including vinyl, PVC, polycarbonate, paper, thermoforming films, polyethylene, polyester, and other plastics. In fact, I can't even recall the last time we ran a curing system at 300 watts/in.
As we were fine tuning our voltage adjustments and lamp designs, we also started to consider the effect of this low-temperature curing on our inks. Namely, we wanted to see what the results were with different ink/lamp/power combinations. Our goal was to make sure every color in multicolor jobs was curing properly, with no over or undercuring of any color by the time the job was complete,
We started by testing all the colors we typically print at different dryer speeds and power levels. Our first test with each color involved the lowest possible power settings and fastest possible belt speeds. We measured and continued adjusting belt speed down and/or lamp power up until the ink cured. We continued measuring and adjusting until we identified the belt and power settings at which each color became overcured and brittle. We now had an operating window that described the ideal curing parameters for each of our inks.
Did you enjoy this article? Click here to subscribe to the magazine.