A system for more quickly changing the blankets on decorating presses has been launched by Germany’s KBA-MetalPrint.
The Rapid Blanket Change (RBC) system is said to cut changeover times by more than half, thereby raising efficiency and productivity. The RBC process is initiated by simple push-button control by a single operator.
Printing of metal sheets can place high demands on presses, in particular on components such as blankets which are in direct contact with the substrate and are exposed to high stresses, with the edges of sheets cutting into them. It can result in surface damage to the blanket and subsequent faults in the printed product.
If, for example, a larger format print job is set up after a small format job, surface damage from the smaller job results in unwanted non-printing areas on the sheet. To solve this problem, care must be taken at the job planning stage to ensure that the size of the formats is progressively reduced. In addition, blankets have to be changed frequently – typically once or even several times a day, depending on the frequency of the change of format and the orders received from customers.
Manual changing of a blanket traditionally takes between six and eight minutes per printing unit. If all of the blankets of a six-colour press are changed, this means a production downtime of at least 36 minutes, says KBA. It also requires two operators to carry out. With the RBC, changes can be reduced to two minutes per unit and can be easily performed by just one operator. This leads to a time saving of 65 percent and allows the second operator to be assigned to carry out other tasks, for example preparing the print job at the control console. For example, on a six-colour MetalStar 3 press, in which the blankets are changed on a daily basis this results in reduced downtime from three hours to one hour a week.
With the RBC system, the old blanket is automatically ejected, and the operator can then insert the new blanket with the help of the blanket change unit through a shaft in the tensioning rail. As soon as a sensor detects the correct position, all other operations are performed automatically, thus significantly increasing process reliability.
A new blanket, which KBA supplies for UV and conventional inks, was developed specially for the automated blanket change using the RBC system. During development, particular attention was paid to functionality of the system.
The structure of the blanket was also adapted to the needs of metal decorating. Instead of the fabric carrier layer usually used, the MetalPremium RBC blanket has a thermoplastic synthetic material as a carrier. This is claimed to eliminate the possibility of the blanket stretching, doing away with the need to re-tension it, or having the need for packing sheets. Together with the sensor-controlled replacement of the blanket, reproducibility is said to be significantly increased.
A special feature of the MetalPremium RBC blanket is that it can be stripped to match the format of the substrate. This prevents unwanted ink transfer from the printing plate and the blanket to the impression cylinder outside the print format, so-called ‘picture framing’. Cleaning intervals of the ink transfer can also be prolonged. Picture framing often occurs in UV printing presses and requires a lot of cleaning, particularly if a UV intermediate dryer is used, as ink dries on the impression cylinder.
More information from KBA-MetalPrint GmbH, Wernerstraße 119-129, 70435 Stuttgart, Germany. Tel: 49 711 6 99 71-0. Website: www.kba-metalprint.com