UV Curing 101
UV Curing technology has been growing for decades. What was once a revolution for printing due to its instant curing has expanded to other industries and technologies. The method of curing is photochemical upon exposure =to specific wavelengths (when using LED) or exposure to high intensity UV (standard UV lamp).
What are UV inks used for?
Adhesives, Resins & More:
UV inks have a reputation for being used for screen printing but that is only becoming one piece of the pie. Adhesives and resins may require UV curing. UV inks provide many benefits for screen printing such as remaining in a liquid state unless exposed to UV light. Adhesives and sealants are formatted in either epoxy or acrylate forms. Applications using plastics, rubbers, glass, metal and ceramics rely on adhesives and sealants. Adhesives offer bonding that is not visible. Sealants cure and form in place. Conformal coatings (layer of protection for circuit boards) and encapsulants (electrical insulation) are applications that typically use UV curing.
UV LED Curing:
LED inks may have less options but if your application is simple, it is likely you will be in luck. One of the biggest detractors for switching to LED is the cost for the module typically being expensive. Your ROI is for LED is dependent on your use, the more LED is used due to it not using any consumable lamps and having a long life time. Typically the LED lifetime can last over 60,000 hours. You also do not need to exhaust anything because the LED does not emit ozone. The form factor of the LED is also much more compact when compared to the traditional UV lamps. The LED consume a fraction of the energy in comparison. Rather than emitting a high intensity light to encompass may different wavelengths, the LED only uses one wavelength (395 nm is the most popular). The LED module will need to be substantially closer to your product for successful curing than traditional UV lamps. The technology for UV LED is still being perfected and is the future for the UV curing industry.
UV inks are ideal for printers with consistent orders and want instant curing to drastically increase your overall throughput. The curing process for uv inks is almost instant and once finished, is able to to be packed for your customer. The benefits UV inks offer over solvent based inks are instant curing and staying a fluid state unless exposed to UV light. The UV light from your factory lights can partially dry the ink if left out. We encourage printers of UV inks to cover the machine so no light comes in if you want to leave the ink on the screen over a break in the day or overnight. UV inks are great If you are printing multicolor designs (in large quantities), especially on an automated machine for a consistent throughput.
When to Pretreat:
UV inks are not as resilient as solvent based inks. You may be printing plastic cups for one time use or glassware that will be exposed to dishwashing. In the case of the product that will be used repeatedly, SA heavily recommends pretreatment, which can range from flame, plasma and Pyrosil.
You may perform a dyne test or a cross scratch test. The crosshatch is simple, if a blade is pressed against your printed image and it is scratching off, it will not stand the test of time. You may even try using your fingernail to see if the ink flakes off. A dyne test requires a dyne kit with droppers. If you have a good dyne level (instructions will come with), the liquid will stay in its liquid form. If your dyne level is less than optimal, the liquid will bead out and not leave the full liquid line on your cup that you are looking for.
UV Lamp Curing:
The most popular form of UV curing are still traditional UV lamps that cover a wide array of wavelengths. The lamps are high intensity and require proper shielding so light is not exposed to the operators’ eyes or body. All SA conveyors come with a blower that not only takes out the ambient heat from the lamp but also has a duct connection so that you may exhaust the ozone from the lamp outside of the building. There are many more options for inks, adhesives and more for traditional UV as it has had decades to perfect formulations. The life of a UV lamp is approximately 800 hours. You have much more freedom in controlling the distance between your product and the UV lamp for curing as opposed to using LED.