Posted: 10th July 2020
There are three main types of folding machine: Buckle or Plate, Knife and Combination.
Combination folders use buckle and knife fold units together.
Buckle Folding: A buckle folding station consists of three rollers and a buckle plate. The first two rollers are arranged vertically above one another and their job is to carry the incoming sheet into the buckle plate until it reaches an adjustable feed guide stop.The sheet is delivered into the buckle plate at a speed determined by the characteristics of the paper. As the lead edge of the sheet strikes the feed guide stop, the sheet continues to be fed into the buckle plate, creating a buckle in the space between the three rollers. As the excess paper drives downwards it is grabbed by the rollers and the fold is formed as the sheet passes through them.
Unlike knife folding, buckle folding is not restricted to any cyclical movement, which makes it ideal for high-speed folding. Each folding station can fit up to six buckle plates, arranged alternately above and below each other, allowing for a large number of fold variations.
Knife Folding uses a vertically moving knife and two rollers rotating in opposite directions. The sheet is carried from the feed to the folding station until it makes contact with the sheet stop. At this point, the knife descends vertically, plunging the sheet between the rollers that have been set to the thickness of the sheet going through them. As the sheet passes through the rollers, it is pinched and the fold is formed. This folding process is dependent upon the repetitive action of the knife.
Only one folding knife is to be found in any one folding station. For every subsequent fold, it is necessary to have a further knife folding station at right angles to the preceding one. Printers and binders specializing in folding large sheets usually use knife folders.
Folding Machine Feeders - There are 2 types of feeding systems used by folders:
The first is Flat Pile, this is where the paper is placed on a feeding table and each sheet is then transported into the machine by friction or an air-controlled suction-wheel. A variation of this is palletized feeding. This is the case where an entire pallet full of paper may be placed on the feeding table.
The second type is called Round Pile or Continuous. This involves the sheets being placed onto a belt on a table or rollers, which takes it around the end of the machine and then each sheet is individually pulled into the machine by an air-controlled suction-wheel. The sheets of paper will be separated by help of blowing air between.