One of two basic types of systems used to feed sheets of paper into a sheetfed offset printing press (in contrast to a stream feeder). A single-sheet feeder feeds paper into the press at a speed equal to that of the press itself, which provides less sheet control than that obtained when using a slower stream feeder. As its name indicates, a single-sheet feeder feeds one sheet at a time, the first sheet completely clearing the pile table before the next sheet is pulled from the pile. (A single-sheet feeder is also known as a successive sheet feeder.) The configuration of a single-sheet feeder is basically the same as that described in Feeding Section: Sheetfed Offset Lithography and is thus very similar to a stream feeder. However, there are some differences in the configuration of the pile table, and in the sheet-separation unit. In contrast to a stream feeder, sheet separation on a single-sheet feeder typically occurs at the front (or gripper) edge of the sheet, rather than at the rear. Consequently, rear guides on the pile table are oriented somewhat differently. When utilizing a single-sheet feeder, the double-sheet detector (a device that determines and shuts off the feeder when an increased thickness of paper is passing beneath it) needs to be set differently than that used with a stream feeder. (See also Stream Feeder.)
|