Vertical form fill sealing machine
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The Vertical form fill sealing machine (VFFS) is a type of automated assembly-line product packaging system, commonly used in the packaging industry for food, and a wide variety of other products. The machine constructs plastic bags out of a flat roll of plastic film, while simultaneously filling the bags with product and sealing the filled bags. Both solids and liquids can be bagged using this packaging system.
The typical machine is loaded with a continuous flat roll of plastic film, which has had labeling and artwork applied to the exterior or interior of the film. Note that while plastic is the most commonly used packaging material in the food industry, the technology can also be used to form continuous paper and fabric product containers by changing the edge sealing/seaming methods. For some products the film may first be fed through a sterilizing chemical bath and dryer prior to use in the packaging system.
The film approaches the back of a long hollow conical tube, which is called the forming tube. When the center of the plastic is near the tube, the outer edges of the film form flaps that wrap around the conical forming tube. The film is pulled downward around the outside of the tube and a vertical heat-sealing bar clamps onto the edges of the film, bonding the film by melting the seam edges together.
To start the bagging process, a horizontal sealing bar clamps across the bottom edge of the tube, bonding the film together, and cutting off any film below. This sealing bar can be on a fixed height, which is called an intermittent sealing process. Faster systems include a sealing bar that moves down with the bag while sealing. This is called a continuous process. The sealed tube end is then lowered onto a precision weighing table and the product to be bagged is dispensed through the long conical tube in the center of the bag. When the gross weight of the product-filled bag is reached, filling stops, and the horizontal sealing bar seals the top of the bag, simultaneously forming the bottom of the next bag above. This bag is then cut off from the tube and is now a sealed package, ready to advance onward into the product boxing and shipping processes.
During the final sealing process, the bag may be filled with air from a blower or from an inert gas supply. Inflating the bag helps reduce the crushing of fragile products such as potato chips, while inflating with inert gas helps drive out oxygen and retards the growth of bacteria that would spoil the product.
The feeding of material and cutting of the pouch can be determined either by pouch length, or by indexing to an eyespot, which is detected by a visual sensor. While single web systems are popular for food applications, the dual web four side seal system is often popular for IVD and Medical device products. Closely related is the horizontal form-fill-seal machine, which generally uses more floor space than a vertical system. Modern advancements in pouch forming technology have allowed for smaller and smaller Vertical pouch forming systems.
Many food filled packages are filled with nitrogen to extend shelf life. Food manufacturers are often looking for ways to improve their geographical reach or otherwise extending the shelf life of their product without the use of chemicals. Nitrogen filling is a natural means of extending shelf life. More and more manufacturers are choosing to create and control their own nitrogen supply by using an on demand nitrogen generators.
Dual web systems 
Dual web systems are also available for four side sealed pouches, as well as pouches requiring different materials for each side. Dual web systems use two rolls of material instead of one, which are fed in from opposite sides of the machine. The bottom and sides are heated sealed together to form the pouch, and the product is loaded from the top. The pouch with the loaded product then advances downwards; the top is sealed and the pouch is cut off. The sealing of the top of the pouch forms the bottom of the next pouch. During this process a tear notch may be added.
See also 
- Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6
- Soroka, W, "Fundamentals of Packaging Technology", IoPP, 2002, ISBN 1-930268-25-4