Flexible FIBCs, also known as bulk bags, big bags, or jumbo bags, are industrial containers made of flexible fabric designed for storing and transporting dry, free-flowing products such as sand, fertilizer, and plastic pellets.  FIBCs are typically made of thick, oriented polypropylene woven fabric [4] and can be coated or uncoated. They are typically about 45-48 inches (114-122 cm) in diameter and 100-200 cm (39-79 inches) in height. Their capacity is typically about 1,000 kg or 2,200 lbs, but larger FIBCs can hold more cargo. A FIBC designed to transport one ton of cargo weighs only 5-7 lbs (2.3-3.2 kg).

The manufacturing process of FIBC bags is a multi-stage process involving the transformation of raw material polypropylene (PP) into finished, tested bulk bags.

Raw Material: 

The primary material is polypropylene (PP), a versatile polymer chosen for its high strength, durability, and affordability. The production process begins with PP resin, a granular raw material, which is typically mixed with additives (such as UV stabilizers for outdoor applications or antistatic agents for the safe handling of flammable materials) during the compounding step.

Tape Extrusion: 

The composite polypropylene is melted and extruded into a film through a flat die. This film is then oriented and stretched (called strip extrusion) to form a high-strength strip yarn. This oriented stretching process aligns the polymer molecules, significantly improving the yarn's strength-to-weight ratio.

Weaving:

 The strip yarn is wound onto a large spool and then fed into a circular or flat loom. Here, it is woven into a durable fabric, typically using a plain weave. This fabric is made into a continuous tubular shape, called circular knit fabric, which naturally forms the body of the bag, eliminating the need for side seams, thus increasing strength and reducing potential breakage points.

Lamination (if applicable) :

For packaging bags requiring moisture or dust protection, a multi-layered composite film is produced using an extrusion lamination process (e.g., PP woven fabric covered with a layer of polyethylene or polypropylene film). The composite film is then cut to the required size.

Cutting and Printing:

Large rolls of woven fabric are cut into pieces of specific sizes according to the bag design. These pieces are then printed with product information, safety warnings, labels, and handling symbols using flexographic printing technology.

Sewing and Assembly:

The cut pieces are sewn together using high-strength polypropylene (PP) or polyester thread by industrial sewing machines. This process forms the body and adds lifting loops, as well as creating the outlet (if necessary). Critical seams, especially those around the lifting loops, are typically double-stitched or reinforced with webbing for security.

Quality Control and Testing: 

Quality control checks are performed throughout the production process. The final packaging bags undergo testing, typically following standards established by organizations such as the International Federation of Flexible Intermediate Bag Manufacturers (FIBCA) and the International Organization for Standardization (ISO). Key tests include:

Top Lift Test: The bag is filled to its Safe Working Load (SWL) and then lifted using its loops.

Stacking Test: Simulates stacked storage conditions to check load stability.

Drop Test: Evaluates the durability of the bag and its seams when dropped from a specified height with controlled contents.

Bags that pass the tests are then compressed and secured for transport.