THE 4 STAGES OF BAG MAKING
(4) PRODUCT
All
standard bags and carriers have one side open and three sides closed. There
are 2 main methods of making bags - sideways or lengthways.
(a) Sideways - with this method, the bags are produced sideways-on by a machine using a hot knife to simultaneously cut and seal the tubular film to form the sides of the bag, the bottom being the fold in the tubular film. These are known as side-weld bags.
(b) Lengthways - using this method, the layflat tube is pulled through the machine and a hot wire makes a seal across the tube while a flying knife (a sharp blade traveling at great speed), cuts the film below the seal whilst the film is motionless for the sealing process. Thus the seal forms the bottom of the bag and the folds of the layflat tubing, the sides. These are known as bottom-weld (or end-seal) bags.
There is a third method commonly used, usually for vest-carriers and heavy duty pouches, this is where the bags have a bottom-weld type seal at both ends, or both sides. This is known as mixed or skirt-weld (because it leaves a skirt below the seal). On vest carriers, a portion of the bag is then punched out to form the handles and opening section.
typical converting machine, this seals, cuts and punches the bags.
There are many variations on these basic themes which are covered on the bag section of the products pages.
raw material | film | printing | final product