by Rick Bartelli, Engineered Printing Solutions
When it comes to UV inkjet printing, reflective, transparent or glossy substrates do not always play nice. These substrates can be anything from glass and crystal to simply any type of shiny media that causes UV light to bounce back into the print heads.
The problem with UV light reflecting back into the print head is that it results in curing the inks within the nozzles and on the nozzle plate itself. This can cause serious (and costly) damage to the print head and therefore shorten the life of the head unnecessarily.
The following are some tips on how to prevent UV curing from damaging print heads:
- Eliminate the use of refractive materials when manufacturing fixtures or printer jigs. When designing a fixture, be sure it is a dark, matte-finish material that covers any negative space between parts to block UV light from bouncing back to the print heads.
- Consider the angle and intensity of the UV lamps. You should always use the lowest amount of UV possible to gain full cure for your application. If your machine was not supplied with UV light shims, contact the technical service department to inquire about this feature.
- Always print onto substrates that are flat or parallel to the head array, and be sure the platen gap is no larger than 1.5mm. If you happen to be printing on a mirrored substrate that is flexible, be sure to attach it to a flat material first.
- Be proactive and check the health of your nozzles frequently. Perform an auto cleaning every other platen and to ensure all nozzles are working, run nozzle checks every hour of production. If you notice that ink is curing either in the nozzles or on the face plate, flush the affected head with maintenance fluid.
- Always perform ink nozzle checks at the end of a shift. If any nozzles are missing, clean your print heads before powering down the printer.
Prematurely damaged print heads (due to UV light refraction and reflection) are expensive and unnecessary. Follow the tips above to avoid this issue and ensure proper care and functionality of your inkjet printer.
Reprinted with permission from Engineered Printing Solutions. See the original article at www.epsvt.com.