Quality raw materials play a critical part in production of an FIBC. Typically, these are not detectable by the human eye. An FIBC may look like a quality bag, but there are many raw materials and additives which go into the production (or not) of fabric, yarns, stitching etc. These can have a tremendous effect on cost as well as performance of an FIBC.
Fabric production starts with the extrusion process; where polypropylene (PP) resin, calcium carbonate and the appropriate additives are measured and fed into the extruder via computer program to produce PP tapes. This is a process of melting the PP and other components, then feeding it through a water process where PP sheets are produced. This sheeting is then cut into tapes, headed and stretched over a process of rollers.
According to the fabric requirements the tapes produced by the extruder can vary in thickness and width. These tapes are wound onto bobbins and become the basis for the weaving process. There are two types of looms, the Sulzer weaving machine where the tapes are wound onto a large beaming roll which used to feed the tapes, these fabrics are used to make the U-Panel, 4 panel and form stable bags. A circular weave machine produces fabric in measure diameters or lay flat widths, this is used to produce circular shapes bags.
Fabric can be produced as both coated and uncoated as required. Coated fabric is laminated with a layer of polypropylene which provides protection from moisture, contamination and sifting. Uncoated fabrics are breathable. You can test fabric by blowing on it (providing no hazardous substance has been in contact with the material). Before the coating process, the fabric to be coated is passed through a static eliminator to release dust particles. The dust particles are removed by using a vacuum machine to prevent contamination. In this way, no dust stays between the coating and the fabric surface.
After the production of fabric, printing can then be done as required. All printing inks are FDA approved for food contact. We use black, blue and red colors of ink for making loops, stitching point of document pockets and inner liners. The major characteristic of this ink is to dry quickly so that it will not run or smear.
The woven fabric rolls are fed into computer programmed cutting machines and cut into pieces of required sizes for the various parts of each bag. Cutting process? Heat cutting?
  • The liner is made from blown film produced to exact recipes and is then sent to liner divisions that form shape the liners to the proper specifications using heat sealing machinery
  • Main reasons for using liners
  • Containment and integrity of the product
  • Protection of the surrounding environment
  • Prevention of moisture (ingress) – dry products
  • Control and prevention of air / gas migration
  • Control aromas / tainting
  • Enable suitable handling of liquids and semi-solids
  • Prevents leakage of products
  • Enhance outer package
  • Electrostatic protection
  • Types of liners
  • Tube stock – an extruded tube, open on each end
  • Bag Style – an extruded tube, heat sealed on one end
  • Gusseted form fit – a liner that can be made from as many as 4 pieces heat sealed together and when inflated mimics the shape of the FIBC, can have a heat seal bottom
  • Form-fit – a liner that has a body, top, bottom and spouts, all heat-sealed to make a concise bulk bag shaped liner that fits inside the bag, can have single or double discharge and heat seal
  • Baffle Liner – a liner built the same as a form-fit, but with heat sealed polyamide baffles inside the liner, can be used inside a large U-panel, or 4 panel to give the appearance of and allow the performance of a baffle bag.
  • Form fit liners are held in place by various style tabs that are attached to the liner material itself. Tabs can be positioned at multiple points on the liner such as around the top and bottom and sometimes down the sides (most secure). Sometimes, tabs are only attached at 4 top points on the liner, which are sewn into the top of the bag body (least secure)
  • Liners are heat welded to fit the shape of the bag and sometimes fabricated so that there is a “lip” of the liner material either around the top, or down the vertical seams, or around the bottom or a combination of the above. Attachment is made possible by sewing the liner into the seams of the bags.
  • Photo of the different stitch types
  • After the PP fabric has been woven and cut into individual pieces according to each bags specifications our highly trained employees begin to sew the pieces together to produce the bulk bags. To comply with regulations to produce food and pharma grade bags, all bags are sewn in our own FDA approved clean room. We have extensive plant sanitation and ongoing food grade training program/practices for employees.
Made of polypropylene and attached to the FIBC and used to tie inlet and outlet spouts.
Filler cord is sewn into the seams as required for sift-proof FIBC’s to help prevent the escape of fine dusts and powders
  • Video of a bag being tested, Testing equipment photos
  • All aspects of the manufacturing process are tested, from the raw materials, to the PP tape to the finished product.
  • Different types of testing for finished UN bags
  • Top Lift Test
  • The FIBC is filled with PP granules
  • Method: A load of 6xSWL is applied on the bag. The bag is subject to this load for 5 minutes
  • Test Passing Criteria: No break on the FIBC
  • Drop Test
  • The FIBC is filled with PP granules or emery dust
  • Test Method: The FIBC is suspended by hoist and it is dropped on its base. The drop height differs according to the packaging group.
  • Test Passing Criteria: No damage to seams or loss of content
  • This is one of the more difficult tests and is the reason that UN bags are usually required to have heavier fabric, folded seams and dust proofing.
  • Topple Test
  • The FIBC is filled with PP granules or emery dust
  • Test Method: The FIBC is placed on the movable platform. The FIBC is toppled onto its top.
  • Test Passing Criteria: No loss of content
  • Righting Test
  • The FIBC is filled with PP granules or emery dust
  • Test Method: The toppled bag, is tightened from the two loops and the bag is put on to its base
  • Test Passing Criteria: No loss of content
  • Stacking Test
  • The FIBC is filled with PP granules or emery dust or with a mixture of PP granules + emery dust
  • Test Method: The bag is put under the compression unit. According to the required stacking load the pressure is increased. The bag is submitted to this load for 24 hours
  • Test Passing Criteria: No loss of content
  • Tear Test
  • The FIBC is filled with PP granules or emery dust
  • Test Method: The bag is put under the compression unit. On the wider side of the bag, a 10 cm cut with a 45 degree angle to the vertical side is done. Then a load of 2*SWL is pressed on the bag for 5 minutes. The bag is then lifted and suspended for 5 minutes in this position.
  • Test Passing Criteria: The cut should not propagate more than 25%
After sufficient testing, bags are baled onto a pallet and wrapped for additional security then loaded onto a container bound for the United States. Once the container arrives at the U.S. port, arrangements are made for deliver to our warehouse in Grovetown (unless a drop shipment to the customer is arranged). Bags are checked in by our quality control department to ensure the order has been properly processed and then shipment is arranged for delivery to the customer.