Effective UV technology mobilizes reserves of output
UV curing - being very common in the continuous label printing - made important progress in the last few years. Systems where all components like lamps, reflectors, power supply devices, control units, etc. match together, making possible a considerable increase in performance. IST METZ GmbH, Nürtingen, developed such an equipment package particularly for the Gallus R200 range which is the most successful letterpress printing press with more than 1000 installations. New presses can be equipped with MBS Minicure style and existing printing lines can be upgraded.
The MBS Minicure units - designed for installation into label printing presses type Gallus R200 or R160 - are extremely high-power compact UV systems. The lamp modules situated after each printing unit are each equipped with a high-power 200 W/cm lamp. They replace the originally supplied two UV lamp modules equipped with 2 lamps (each with 120 W/cm), normally being installed in this press type. Printers appreciate the worldwide successful press from St. Gallen mainly because of the very good printing quality but also because of the high reliability and easy handling.
Double printing speed
According to indications from users, the production output in practice is between 30 and 40 m/min on average. A barrier to higher speeds has often been the UV curing so that a label printing company asked IST METZ two years ago for an efficient UV system. First installations of the MBS Minicure development showed that the printing speed can be doubled in individual cases. Under test conditions, speeds of even 100 m/min were achieved in UV screen printing with high ink application.
Due to the experience with ten systems which IST already supplied in total, they guarantee curing at printing speeds of up to 60 m/min when high-quality UV inks and varnishes are used with a combination of letterpress and screen printing. The printing companies who have already equipped their Gallus presses with an MBS Minicure system are for example Arca Eticette in Italy, Cetis in Slowenia, Impresstik Pty Ltd in Australia, Pago Group, Römer Etikett in Marburg/Germany and Talis Haftetiketten in Krefeld/Germany.
Individual components matched together
IST indicates various reasons for the improved drying performance. First, a newly developed lamp type with higher UVC emmission within the short-waved sector is used. Moreover, the individual components like power supply devices and UV lamps match together so that energy is used as effectively as possible. A further very important aspect is the efficiency of the reflectors. The reflecting surface is metallised with high-grade aluminium in a high-vacuum process and finally covered with quartz coat in order to prevent corrosion. High-grade aluminium has excellent reflective characteristics.
The automatic exhaust air flap adjustment has also an important influence on the UV emmission of the lamp as the output is dependent on optimum cooling of lamps, reflector and lamp housing. The exhaust air temperture is monitored by a thermo sensor inside the lamp housing and is adjusted automatically to the load of the UV unit by means of a servomotor with butterfly valve. Therefore, a controlled cooling is guaranteed for the complete length of the lamp.
Reduced energy consumption
As a result, the required drying performance can be achieved with one lamp module which has only one UV lamp with 200 W/cm instead of two UV lamps with 120 W/cm. The energy consumption is therefore reduced by 40 W/cm per printing unit. For example an output of 7 kW can be saved on a printing press with 7 UV units. On a two-shift operation this would mean 3600 working hours and assuming a current price of 0,28 DM per kW/h this would be an annual saving of over 7.000 DM. Furthermore, it should be taken into account that in most cases 70 to 80 % of the output is sufficient for curing as practice has shown. As the standard equipment includes the SLC control adjustable from 50 - 100 % further money can be saved.
Moreover, a couple of further advantages result from the MBS Minicure. As the system needs one lamp per UV-unit only, the units need considerably less space between the printing groups. Looking at the substrate, the operating staff can control optically the print directly after each colour when making the machine ready. Also as a consequence, maintenance and spare part costs drop as the number of lamps and wear-and-tear parts is halved.
Slide-in cassettes system for quick change-over
Maintenance is further simplified by the special lamp unit design, which consists of a fixed mounting with a slide-in cassette. The slide-in cassette comprises lamp, reflector and rotary actuator and can be changed within a few seconds as connections for exhaust air, control voltage, lamp tension and compressed air is produced automatically by sliding in. As a so-called „stand-by slide-in“ is part of the supply for MBS Minicure units, there are no production interruptions due to change of UV-lamps or for reflectors cleaning.
IST has taken special care of maintenance convenience when designing the reflector. For this system IST uses a rotary reflector rotating by 180° around the UV-lamp when the printing press is stopped. As it is driven via a pneumatic rotary cylinder, there is no need for mechanical parts like chains or cogwheels so that the rotary reflector works without any wear and tear.
Cooling cylinder technology for foil printing
IST has had increasingly demands from many different users to amplify the range of application possibilities. The UV-unit can process a broad range of different substrates including very thin monofoils. With this aim in view, a new cooling system has been developed. A water-cooled cylinder positioned directly underneath the lamp unit makes it possible to print on temperature-sensitive materials like thin plastic foils. However, to ensure true register, IST recommends in such a case to install a corresponding register control-system. If only less temperature-sensitive materials are being used, for example paper labels, a cooled undershielding can be installed alternatively to the cooling cylinder.
Retrofitting a Gallus R 160 for Labelexpo
During Labelexpo GRE Engineering Products AG in Steinbrunn exhibited on their stand a Gallus R 160 which had been retrofitted with MBS Minicure and cooling cylinder technology. The Swiss company offers in co-operation with IST a corresponding retrofitting for the European market. Beside retrofitting with modern UV-technology GRE sees to it that the machines are also technically up-to-date in the printing sector to ensure the performance and printing quality striven for are achieved.
