Depending on the printing ink or adhesive, infrared or UV technology is used for drying and curing. Heraeus Noblelight shows its competence in the field of specialty light sources and systems for printing plants at the drupa in Düsseldorf from 3 to 16 May 2012. Heraeus presents individually developed infrared emitters, UV lamps and UV LEDs for more efficient printing processes at stand C35 in hall 3.
These days the efficient use of energy is an important issue. It is therefore worthwhile to examine industrial processes, such as printing in detail to find methods and technologies that yield the best results while at the same time saving as much energy as possible.
Infrared emitters dry digital prints cost effectively
A change from toner to digital printing promised major cost savings at the British company Bemrose Booth in Hull. Thanks to the use of Heraeus carbon infrared emitters to print car park tickets, drying can now keep pace with the new high-speed print heads.
Bemrose Booth offers a wide range of products such as gift cards, vouchers, calendars and lottery and other tickets. An important feature of car park ticket reels is the use of black ink blocks which signal that the reel is nearly finished and needs to be replaced. These "signal blocks" require application of large amounts of ink. In the past, toner was used for this which did not need to be dried but because of the high costs, a decision was made to change to digital printing. Print heads are used which apply up to 205 million drops of water-based ink per second. However, the very great economic advantages promised by the use of the high-tech printing system could be realised only if drying of the ink kept pace with the printing speed. Following successful tests at the Heraeus Applications Competence Center, a customer-specific infrared drying system was developed and installed at the Hull branch.
The system comprises medium-wave carbon infrared emitters and dries the ink with high efficiency because medium-wave infrared radiation is especially well absorbed by water. The system measures the temperature of the substrate when it leaves the heating module. Depending on the printing speed or ambient conditions, the infrared emitters are regulated to keep the defined temperature. Due to their very short response times, the infrared emitters are switched off virtually immediately when the paper stops and a fan cools the heat-sensitive paper.
Graham Winship, Operations Manager at Bemrose Booth, explains: "It was important to dry the ink quickly and thoroughly at paper speeds of up to 60 metres per minute without damaging the sensitive paper. The Heraeus system does exactly this!"
UV lamp cassette for efficient "lamp" exchange
The emission spectrum of UV radiation is very important for the curing process. The radiation must cause as many photons as possible to react with the coating to completely cure the material and to merge the coating to the substrate. Therefore, any curing process is complex and each coating system has its own parameters. In close cooperation with OEM partners, Heraeus has developed a large number of especially adapted UV lamps and replacement lamps for these demanding processes.
An efficient and advanced method to replace the UV lamps in digital printing machines at the end of their service life is to replace a complete UV lamp cassette.