Manufacturing Process of Bulk Bags
FIBC bags are made of polypropylene woven fabrics utilising various processes and expertise of technicians. The PP fabric is also stabilised against UV degradation. Virgin polypropylene fibres are a very versatile material (which is petroleum based) and are used extensively in the manufacturing of Bulk Bags.
Below we are listing various steps involved in making of a Bulk Bag.
Extrusion & Winding
The first step involves extrusion, where a mix of pure ingredients viz. polypropylene granules, UV Master Batch, calcium carbonate, and sometimes colour pigment is melted and shaped into tapes in an Extrusion plant. During this process, the tensile durability of the tapes is checked. The tapes are reeled on bobbins which are stored and later loaded onto looms for weaving.
The bobbins of tapes formed in above stage are loaded onto weaving looms which can be Circular Looms, or Flat Sulzer looms depending upon users requirement. Here, the fabric used in the manufacturing of Bulk bags is formed. The same material is also used for duffle, bottom and top spouts.
Lamination / Coating — Optional
Depending on the requirements of a customer, the weaved fabric may be laminated with a semi-clear PP film that is bonded to the woven material to create a moisture barrier.
Regular, un-coated / unlaminated polypropylene fabric material is breathable and not suited for products like sugar and salt which should never be exposed to water, including water that gets sucked from the moisture in the air.
Coated or Laminated bulk bags are convenient for the transportation of light powdery products, such as flour, that could otherwise sift through uncoated bags when moved or shaken.
The PP woven fabric in the form of rolls fed into an automatic cutting machine where it is cut into different panels of a specific size.
The automatic process assures the uniformity in size of the cut panels. These panels are now ready for stitching or printing.
Once the fabric cut panels arrive after cutting, they are put into the printing machine, and the logo/artwork impression is made over the fabric. It is this stage at which the brand name or logo of the customer is printed on the bag. The artwork/logo up to four colours can easily be reproduced.
The loops of the bags used to lift the kits are made at this stage. The more massive tapes of polypropylene are weaved together on needle looms to give them the shape of webbings. This webbing is cut into a specific size and stitched to the bag to form the lifting loops of the bags. The colour of the strap is white as standard, but can also be made in any desired colour like Red, Blue, Green, Yellow etc. depending upon customer requirements.
All the components like fabric cut panels, webbings, spouts, duffle are brought together and stitched by qualified tailors to give shape to each bulk bag. The bags are thoroughly inspected by qualified supervisors to ensure that it is free from any defects.
The technically qualified persons are involved in the quality checking of the bags. Every bag is thoroughly inspected ensuring that it is safe to use.
Cyclic Top Lift Test
Some randomly selected bags are also picked up from production and are subjected to Cyclic top lift test on the test rig. It ensures that the safe working load criteria of the bag are met.
Packing / Palletizing
After inspection, the bags are folded and placed inside a bale press machine and packed on pallets which are ready to be loaded into a container.