Raedebeul-based KBa revolutionised the sheet infeed process with launch of its no-sidelay Sensoric Infeed System (SIS) at Drupa 2004. Printing press manufacturers and the graphics industry had for years been trying without success to simplify the process of feeding and aligning the sheet in a sheetfed offset press, a process complicated by the high running speeds involved.
One of the chief aims was to make the process stable and reliable without the need for manual intervention even with frequent changes between very different printing substrates. The designers from Saxony managed to achieve this feat in the no-sidelay infeed system, which is a key USP of the 18,000 Rapida 105 medium-format press on the world market. The SIS reduces or bypasses troublesome process stages in sheet feeding. Printers like that too. One in three KBA Rapida 105 machines delivered today is now fitted with this system.
Reducing troublesome process stages
In traditional mechanical or pneumatic side lays such as those still the norm even in modern sheetfed offset presses, the incoming sheet is first braked, stabilised in the front lays and then aligned at the sidelay tabs in a pulling process involving many subsidiary steps before it goes through the swing infeed. In KBA's SIS a sensor continually scans the edge of the sheet. This eliminates the risk of the scanning result being negative influenced by the paper fibres. The gripper bar is pre-aligned in the single-revolution transfer drum according to the information recieved about the position of the sheet edge. Thus the bar is already roughly aligned when it recieves the sheet. Precise lateral displacement of the gripper bar enables the sheet to be subsequently positioned exactly before being transferred to the first impression cylinder.
5 sheets per second aligned exactly
The incoming sheet can be adjusted precisely along the entire route from the swing gripper to the impression cylinder - which means there is almost twice as much time available as in traditional systems. This is essential give that up to five sheets a second must be aligned in register at production speeds of 18,000 sheets/hour. This figure alone indicates just how important no-sidelay infeed is for high-performance sheetfed offset printing.
One of the key advantages of the innovative KBA solution is that the feed process in the front lays is not interrupted by a sidelay process. This gives more time for stabilisation and alignment of the sheet. SIS reduces few malfunctions and enables a more precise infeed register to be achieved both with thin material, which sometimes tends to buckle, and rigid sheets, which can jump out of the front lays at high speed. A side effect is that there is no need to adjust the previous side lay manually when changing between different printing substrates. Mechanical damage to sensitive printing substrates is also precluded.
30 machinees were delivered with SIS in 2005, and the trend is on the up:in 2007, the same figure will be reached as early as mid-February. Today, for instance, the intelligent feed system is in use in cardboard machines, eg at Hager Papprint, Ravensburger Spieleverlag and Schurpack (all in Germany), commercial web offset presses for 4 over 4 and 5 over 5 printing (eg Arkle Print/UK, Ultra Litho/South Africa, Tuschen Druck+Medien/Germany) and special coating presses such as a 14-unit Rapida 105 at Bolger Vision Beyond Print/USA. Roughly one in three 18,000sph Rapida 105s is now fitted with SIS.
No-sidelay infeed in a Rapida 105: The sensor is positioned underneath the LED light on the left
Almost one in three Rapida 105s now has SIS:this photo shows an eight-colour perfector press for 4 over 4 printing and a six-colour press with coater and extended delivery at Tuschen Druck + Medien in Dortmund, Germany