Essentially, a flying paster allows a web offset printing press to print continuously without having to stop.
The basic function is to paste a roll that is about to finish onto a new roll. What makes the flying paster unique though is that it does so by making the new roll match the surface speed of the exhausted roll. When it does, the splicer triggers the tape to stick to the two webs and quickly cuts the expired roll. Since the new roll is running at the speed of the web press, the change is virtually seamless and only wastes very few properties.
The process takes place by timing the position of the tape to the exact position where the splice will take place. A laser will ready a mark put on the roll so that it knows the speed of the roll that is turning as well as the position of the tape itself. The speed of the roll is adjusted to generate the position and timing. In this respect timing is critical. If it is slightly off, the splice will miss.
Flying pasters are used mostly on high speed web presses. Zero speed splicers are also common, but are more limited with presses that run as high as 100,000 copies per hour. Faster production necessitates a flying paster. Modern flying pasters can handle speeds well over one hundred thousand copies per hour.
Many manufacturers are now integrating various functions into the flying paster such as the infeed and web guides. The web guides are then no longer cared for by a tilt box, but instead by moving the roll itself. This takes strain off the web as you no longer have to twist it to line it up with the printing plate.
Flying pasters save the web press much in downtime and waste. Offset presses no longer have to shut down change rolls. In many cases, presses that have automatic blanket washing systems can splice during a wash saving further waste for the pressman. On most typical systems, the press wastes less than one hundred copies and retains the register and cutoff throughout the process as little web wander and tension fluctuation occurs.