In order to maintain optimum print quality over the entire service life of an offset press, it is essential to take proper care of its key components – the offset printing units.
The introduction of offset printing in label presses heralded in a new era. Label production can now also benefit from offset printing's high resolution, and its fast and cost-effective plate changes. Offset printing is, however, far more complex than letterpress and flexographic printing. This is evident from a look at the printing unit.
Naturally, all mechanical components are subject to some degree of wear. To ensure optimum interplay between all components and thus that the entire system remains operational, Gallus recommends that its customers adopt a three-stage approach:
1. Regular system maintenance as specified in the machine documentation
2. Replacement of critical wear parts at the appropriate time
3. Complete overhaul of the printing unit at the appropriate time
Correct care pays off
Based on experience from the field, it is clear that companies who fail to look after and maintain their presses properly due to high production pressure are faced with falling press productivity over time. It becomes more difficult to set precise screen vignettes, more time is needed and more waste is generated. Production units may even grind to a halt. Productivity can only be kept at the same level by ensuring proper cleaning and complying with the maintenance cycles specified in the machine documentation.
Production is also much more reliable if critical wear parts are replaced at the appropriate time. In offset printing, these parts are the distributing and rubber rollers, which need to be replaced at regular intervals according to the level of utilisation. This is necessary because roller wear causes their diameters to change over time. If these diameters exceed or fall below the permitted tolerances, ink is applied unevenly over the print area, which has a negative impact on print quality.
The above-mentioned steps can significantly extend the service life of a printing unit, but if top print quality can no longer be achieved by looking after wear parts and replacing them when necessary, this may be an indication that the entire printing unit needs to be returned to Gallus for a complete overhaul. This involves replacing all the rollers and all other mechanical parts that are subject to wear. The properties and service life of an overhauled printing unit are equivalent to those of a reconditioned system.
Differentiated approach
The support Gallus offers its customers to ensure reliable operation of their offset printing units is also split into three stages.
1. Gallus Educate training packages offer various options for obtaining in-depth knowledge and skills relating to machine care and maintenance. Particular mention should be made of the three-day offset printing seminar, which sets out the strategy for Gallus presses in a transparent way that is easy to understand. Gallus also offers customer-specific training to provide in-depth knowledge on the care and maintenance of the entire printing system.
2. The process of changing complete rollers is simplified by the fact that pre-assembled units with gears and bearings already fitted can be obtained from Gallus. As a result, printing units are operational again in no time at all. A two-day offset printing unit seminar provides details on how to replace wear parts and make subsequent adjustments.
Customers who do not wish to learn how to do this themselves can of course always have trained Gallus service engineers perform the relevant tasks for them.
3. For a complete overhaul, offset printing units are returned to Gallus where they are dismantled and all mechanical wear parts are replaced. All printing unit settings are also readjusted.
Customers can either hire a printing unit from Gallus during the overhaul period or opt to receive a replacement printing unit and leave the printing unit sent for overhaul with Gallus.
Conclusion
Based on experience from the field, it is clear that new approaches to care and maintenance are required to coincide with the introduction of offset printing technology. Gallus supports its customers with a differentiated approach that adapts to the relevant intensity of use and to customers' resources.