Step-By-Step Multi-Wall Paper Bag Manufacturing Process from freeamfva's blog

Step-By-Step Multi-Wall Paper Bag Manufacturing Process

Multi-wall paper bags are used to transport and store dry flowable bulk materials. The paper shipping sack originated over a century ago. Today billions of units are produced and filled each year. Variations of the industrial paper bag include the pasted valve bag, pinch bottom open mouth bag, self opening satchel bag, and the sewn open mouth bag. Get more news about paper bag machine,you can vist our website!

There are two basic types of paper bag: Open Mouth and Valve. An open mouth bag is a tube of paper plies with the bottom end sealed. The bag is filled through the open mouth and then closed by stitching, adhesive, or tape. Valve bags have both ends closed (pasted) and are filled through a valve.

Multi-wall bags are made up of 2-6 layers (plies) of paper and film. Paper plies are generally kraft or extensible paper. For bags requiring moisture or grease protection, a layer of plastic film may be added to the paper plies. The paper itself can also be coated with a thin layer of film. Flexographic Printing - A flexographic press uses photopolymer plates, either digital or conventional, mounted on a printing cylinder.

This process uses very fluid, fast drying solvent or water-based inks. It is especially adaptable to high speed, low cost, in-line printing.
Step 2: Tubing
The initial production of a paper bag occurs on a tuber, a machine which takes several rolls of paper and other materials and combines them over a rigid former into a flat or gusseted tube (a tube with creases or folds in the sides not found in flat tube bags), bonded together with adhesives. Tuber speeds typically run from 150 to 250 feet per minute.
Step 3: Bottoming
The tubes are then taken to the bottom-forming operation as required by the particular specification of bag they will become. The tubes are placed in bundles on automatic feeders which deliver them one at a time at speeds of 30 to 50 bags per minute.

The valve bag is pasted closed at both ends during manufacture with only a corner opening or valve at one end, through which the bag is filled.
Step 4: Palletizing/Drying
Finished bags travel through a metal detector to assure the absence of contaminants. Bags are then palletized and dried prior to final shipment.