There will be plenty of trade fair stands pushing LED UV during Labelexpo Europe. In certain product segments, e.g. in the UV inkjet printing sector, this curing option has already been successfully implemented. This has also long been the case for large-format printing or 3D varnishing, and recently also digital label printing using UV inkjet. At the same time, there is now an increasing number of printing press manufacturers also promoting LED UV. However when it comes to suitability for daily use in narrow web flexo or offset machinery, the economic feasibility of the LED UV systems still needs to be increased for a number of applications. This was also the thrust of the argument from leading machine manufacturers during a discussion round at the recent FINAT Congress in June 2013 in Munich.
Eternal dilemma of technical progress
Companies that are planning on investing in new printing technology may well see themselves faced with a dilemma. Should they go for the conventional UV units, they can rely on the security provided by a long-established technology. However, they may well miss their chance to make the most of LED. Users who focus on this new technology too soon run the risk of paying dearly as they wait for the rest of the market to catch up, finally making their investment economically worthwhile.
The new LED-prepared concept from IST METZ is clearing up this dilemma for users. The UV provider from Nürtingen has developed a classic UV system that is already suitable for the use of LED UV technology. This new development is based on the current MBS-6 product family, first launched at Labelexpo 2011.
Open LED solution for the narrow-web market
With the LED narrow-web concept, presented for the first time by IST METZ in Brussels, users stand to benefit from the combination of established product series MBS-6 and the LED family LUV. Thanks to its particularly efficient use of energy, the MBS-6 system is already used in several narrow-web presses.
Equipping UV units from the MBS-6 series with the “LED-prepared” concept allows for a subsequent conversion to LED UV. To do this, the outer housing remains where it is on the machine, while the MBS-6 unit is replaced with an LED unit that has been designed as a cassette module. Contact to the supply connections is thus made automatically or manually. For a UV system with chill roller, the existing water cooling system can be used to cool the LED unit. This can be subsequently installed for systems without water cooling, or another alternative is the air-cooled LED unit.
Both energy supply and control of the LED-prepared concept from IST METZ are based on the standard equipment of the MBS-6 system. This new concept, including its combination with the printing press, has been designed in such a way that both unit types can be used (classic UV and LED UV). The piling concept within the well-known ELC-X series supplies the power. Future ELC generations can thus be prepared in such a way that either a standard UV curing or LED unit can be used.
Integrated into commercially available machine systems
Most of the LED solutions presented during Labelexpo are based on cooperations with individual machinery suppliers and, from experience, difficult to implement on the market when faced with competition from the free market. With the new LED-prepared concept, users have the option of using both standard-UV curing and LED UV. The UV units can also be integrated into all established models of well-known machine manufacturers. “With investments being made in new printing technology, the user can now select the machine best suited to his individual requirements without being restricted in his choice by the UV equipment,” explains Stefan Feil, Head of Application Technology at IST Metz.
At UV Days in June 2013, IST METZ demonstrated LED UV curing on a narrow-web flexo press with 430 mm working width. The water-cooled LED UV units used here achieved an output of up to 12 W/cm². “With this figure,” says Stefan Feil, “particular attention must be paid to the output in the wavelength range of 385 nm. The output here is to be considered higher than a comparable LED UV lamp that works in the established range of 395 nm.” In addition to better performance, the design of the shorter wavelength provides opportunities to formulate suitable inks and varnishes. It also helps with coordination of the absorbance process to the lamp.
In the meantime, further testing has been carried out on narrow-web and offset machinery using these LED UV units and drying speeds of up to 250 m/min have been achieved. “Following the progress made in recent years, the output achieved by LED systems has by now reached such a level that standard printing speeds are now being met in label printing,” explains IST Managing Director Dirk Jägers. “The use of LED UV technology in narrow-web printing is thus now within reach. As soon as economic operation can be guaranteed in conjunction with technical feasibility, LED UV is sure to achieve a breakthrough. With the LED-prepared concept, the print shops are ready and waiting for this moment.”