Cost effective curing

10 July 2009



Improvements to UV systems offer substantial savings


Energy costs represent a large percentage of production cost for the average printer and with the ink drying system typically being the major energy consumer on a press, anything that can be done to improve the efficiency of the drying system can offer large potential savings to the printer. The major manufacturers of UV curing systems have greatly improved their efficiency, especially by modifications to reflector design and power supply.

The reflector collects the UV light emitted by the lamp and focuses it on the web to cure the UV ink film. By improving the efficiency of the reflector it is possible to collect and focus more of the UV light and thus improve the overall efficiency of the curing system without compromising press speed or thoroughness of cure.

One of the leading suppliers of UV curing equipment, IST uses ray tracing technology to determine the optimum profile of its latest URS reflector which, with additional reflector profiles, is said to have maximised the amount of UV energy reaching the web or substrate. This has been made possibe by manufacturing the reflectors from extruded aluminium, which is then polished to a high degree of accuracy. Coatings applied to these robust reflectors further enhance the amount of UV light reflected and enable them to perform like a dichroic mirror by absorbing the infra red (IR) energy.

This improved reflector design is claimed to result in 20 per cent more energy reaching the web for the same electrical output, which enables the converter/printer to work with lower wattage UV lamps. A 140 W/cm lamp with the new URS reflector is able to achieve the same press speed and depth of cure as a 200 W/cm lamp fitted to a UV system with less efficient reflectors. This translates into a saving of 60 watts of electrical energy for every cm of lamp width or 4.2 kW for each 70 cm wide lamp fitted to a press.

According to IST, a 70 cm wide press fitted with eight UV lamp heads and these new reflectors will be using 33.6 kW less energy to achieve the same cure.

The development of electronic power supply units specifically for the operation of UV lamps, such as the ELC (electronic lamp control) unit from IST, has also helped to reduce energy costs as a result of improved electrical efficiency, reduced electrical consumption during standby mode and by extending the range of output through which the lamp can be steplessly adjusted.

These electronic power supply units have an electrical efficiency of up to 97 per cent, offering substantial energy savings from reduced energy consumption. When a UV press is stopped for plate cleaning or roll changes, the lamps are placed in standby mode rather than being switched off - so that they can come up to full power instantly when the press is started again. With an electronic power supply, the lamp output during standby can be reduced to about 20 per cent, which is considerably less than the 50 per cent standby power requirements of a typical system, says IST.

A press such as the one used for illustration above demands 78.4 kW of energy on full output, which means that roughly 23.5 kWh of energy is saved for every hour it is in standby mode.

Other pressroom savings can be achieved by incorporating design features that can reduce press downtime, such as a fast lamp change system. With such a system the lamp effectively plugs into the lamp holder, without having to make any additional electrical connection so that the time it takes to change lamps is minimised.

Being able to remove and replace the lamp rapidly also facilitates reflector cleaning. In addition, systems that offer low standby power make it possible to reduce downtime further by leaving the lamps in standby mode while changing print jobs over. Here, of course, the savings derived from being able to start the press more rapidly after a job change have to be balanced against the additional cost of leaving the UV lamps in standby mode but, in general, where the job change-over is simple and likely to be accomplished fairly rapidly, there are further savings to be gained.

With the current economic climate it is more important than ever that converters and printers minimise their production costs. Each of these design modifications in its own right offers significant potential savings and when all are combined, as is possible on IST’s MBS-5 and BLK-5 systems, these savings can be maximised.


Rapid change-over lamps save downtime

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Rapid change-over lamps save downtime Rapid change-over lamps save downtime


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