What is a Folio Sheeter?
A folio sheeter or folio-size sheeter, large format sheeter or just sheeter, is a machine that cuts web of paper or board from a reel (or multiple reels) into large sheets, then overlapping and piling them on a stack. The transversal cut for the length of the sheet is done by a rotary knife. If needed, the web is also cut longitudinally by a slitting knife, defining the width of the sheet. The end product of an folio sheeter is a stack of sheets on a pallet, with sizes/formats usually larger than A3 or 11 in x 17 in. Depending on the grammage, the sheets are typically used for offset or digital printing application like commercial printing, posters or the folding carton industry. Examples for folio sheeters from BW Papersystems: eCon, Hawk, Falcon, SheetWizard or Questec RQS-V.
What is a Folio Ream Wrapper?
A folio ream wrapper or folio wrapper or large format wrapper, is a machine that wraps reams of large sheets of paper, board or other flat material into wrapping paper or film. The wrapping material is fed into the wrapper as a web from a reel. The reams are pushed into the wrapper onto the wrapping material, either manually by an operator or automatically by a robot arm. A cross knife cuts the web of the wrapping paper matching the size of the ream to be wrapped. Then the wrapping paper is formed - manually by operator, or automatically - around the ream, by flapping the ends over of the ream lengthwise and fixing them with hotmelt glue. On the short side of the ream, the ends are tucked, folded and then glued to the wrap. The end product of a folio wrapper sheeter is a wrapped ream of sheets, usually stacked on a pallet. Sizes of folio reams are usually larger than A3 or 11 in x 17 in. The end use of the wrapped ream is depending on the wrapped material inside, which can range from sheets of paper and board up to carpet tiles or solar panel film. Examples for folio wrappers from BW Papersystems: GRSX, GRM or GREC.
What is a Slitter?
A slitter is the section of a cut-size or folio sheeter where the paper or board web is slit longitudinally into strips, defining the final width of the sheet. It divides a web into two or more - up to 16 - strips next to each other. The slitter also can trim the web on each side, to achieve the required web width or just to cutting off damaged web edges. The slitter section consists of a number of upper knives and bottom knives - the number depends on the number of strips (or pockets) to be created in parallel, e.g. for cutting the web into 4 strips, 5 slitter knives are needed. The slitter can be single or dual. A dual slitter consists of two slitter units on top of each and is used for multi-web operation. Half of the webs are running through the upper slitter and the other half is slit in the lower slitter unit.
What is a cross cutter?
The cross cutter is often considered to be the heart of a sheeter. The cross cutter or just knife cuts the paper or board web transversally to the required sheet length. The unit consists of two rotating knife cylinders across the full web width, with a blade mounted slightly oblique on each cylinder. The top and the bottom cylinder are rotating against each other. A precise, accurate cross cut is crucial for the overall cut quality. BW Papersystems combines decades of experience in the cutting of paper and board, drawing on the legendary knife technologies from Marquip, E.C.H. Will, Jagenberg sheeters and bielomatik. Cutting trials on a BW Papersystems lab sheeter help to establish the best knife geometry for specific materials to be cut.
What is a pocket in a sheeter?
The term pocket or pockets describe the number of reams (or stacks) of sheets that can be cut and collated in parallel, next to each other, on a sheeter. Example: a 4 pocket cut-size sheeter (or 4-up sheeter) can collate 4 reams - typically 500 sheets of A4 or Lettersize format - at a time, next to each. The more pockets the more productive a sheeter is, as more final product can be produced. BW Papersystems offers cut-size sheeters from 2 to 16 pockets and folio sheeters with up to 4 pockets.
What is cut to register?
Cut to register means that a reel of printed material can be cut into sheets with the cut falling precisely at a point corresponding to a printed mark or water mark.
What is a Splicer?
A splicer is a unit that allows the tail of an empty reel to be joined to a new reel using double sided adhesive tape without stopping the sheeter.
What is a decurler?
A decurler is a device that corrects curl occurring in a web. When material is wound onto a core to forming a reel, the web is deformed to follow the radius of the reel. When the reel is unwound and the diameter of the reel reduces, the web retains some memory and does not lay flat but instead has a curve effect called curl. Curl is removed bending the web in the opposite direction using rollers of various diameters. As the reel gets smaller, the curl increases and do the amount of decurl affect must be increased. Care should be taken to avoid cracking of the web surface. The decurl adjustment is often automated.
What is tension control?
As a reel is unwound, the web must be tensioned to allow it to track correctly through the machine. Tension is produced by a brake or regenerative motor acting on the core. As the reel reduces in diameter and when the machine changes speed the brake effect must be adjusted to maintain a constant tension. This function is normally automated.
What is edge guiding?
Not all reels are formed with perfectly flat ends. In the case, as the reel is unwound the web can slowly move to the left or right. A web guide uses a sensor to monitor the web edge position or 2 sensors to monitor both edges. The system will then make adjustments to either maintain a constant position of the web edge or maintain the web on the machine centre line.
What is a reject gate?
A reject gate diverts sheets containing faults or splices into a waste bin. The reject gate can be operated manually or via a signal from a sensor or inspection system.
What is a reject shredder?
A reject shredder slits the rejected sheets into ribbons to allow easier onward transportation and recycling.
Why is dust a problem of the cut edge?
Because most sheets cut are subsequently printed, it is very important that the cut edges of the sheets be free from dust. When dust is present, it builds up in the printing units creating defects. This not only creates waste but requires the machine to be stopped at frequent intervals for cleaning.
Why does a sheeter not always run at max speed?
Because the sheets have to be transported from one machine section to the next, to arrive at the stack a certain stiffness is required for very high speed running. If the material is lightweight and has low stiffness or if the material contains a high static charge the speed must be reduced to avoid jams. On lighter materials it is normal to cut several reels together (multi-web) to increase the overall thickness and stiffness. If a multi-web operation is not possible, the special technology of the Questec brand from BW Papersystems is an option. The RQS-V sheeter with special sheet transportation system allows 40 gsm paper to run with a single web at 400 m/min.