A Guide to Vertical Form Fill Seal (Vertical Bagging)
What is it?
Vertical form fill seal (VFFS) is a method of packing where the bag is created during the filling process. In simple terms, it involves feeding the product into a bag vertically as opposed to horizontally. This is what it looks like in action:
And this is a common shape that the bag will end up in:
VFFS bags have three seams as demonstrated in the illustration above.
What is it best for?
VFFS is a flexible, quick way of getting a loose, dry product into air-tight, portion-controlled packs. These are known as free flowing products. Depending on the material of bag and laminate used VFFS can preserve your food or product. VFFS can be used to create smaller sachets that sit inside larger packaging, for example a small bag of salt inside a packet of crisps. This type of packing can also be combined with something called gas flushing which helps to preserve your raw material for longer.
What is gas flushing?
Also known as Modified Atmosphere Packaging (MAP) gas flushing involves repeatedly injecting and removing an inert gas into the package in order to eliminate oxygen. The inert gas (something like carbon dioxide or nitrogen) is denser than oxygen so it pushes the oxygen out of the packaging.
The benefits of gas flushing are:
- Extends product shelf life
- Improves product integrity
- Protects against discoloration
- Can provide a cushion-like buffer against damage (think of crisp packets, for example – the air in that will have come from the gas flushing process)
In some situations, depending on the type of product, oxygen may be retain in the packaging. For example;
- In red meats oxygen helps maintain a fresh, natural colour
- In fruit and vegetables oxygen helps maintain respiration
- In fish and some types of vegetables oxygen inhibits the growth of aerobic organisms
What raw materials can be used in vertical form fill seal?
Anything loose, granular and relatively dry. Things like powders, rubs, spices, sweets, seeds, sand beads, blends or ingredients and similar products. VFFS can be used for food and non-food alike. Raw material is normally received in 15kg – 20kg sacks, buckets, drums or similar. If you have a large delivery just get in touch, we can handle any size of delivery. At present, Wepack don’t pack liquids using VFFS.
What size and shape of bag can be produced?
Any square or rectangular bag can be made on a VFFS machine.
- Any length up to 150mm
Colour & print available:
- Plain white
- Plain silver
- Plain clear
Vertical form fill seal creates a pillow bag shape that looks like this:
How are portions controlled using VFFS?
A target weight can be set for each bag meaning you can achieve consistency across all your products and achieve a “minimum fill” so that no bag is underweight.
How are bags sealed?
Bags are sealed using heat and pressure to create a crimp seal. Seals can vary in terms of how flat or pronounced they are. Good vertical form seal is all about minimizing the length of the seal, so that unnecessary material isn’t used, and so that the final bags are easy to pack together in larger, outer packing for transportation.
What materials can the bag be made of?
There are lots of different materials that can be used to make the bag. Normally a polyethylene terephthalate (PET) or Polyethylene (PE) film is used, a common type of plastic. This a strong, robust material that has good sealing properties and will keep many products fresh for a reasonable length of time.
Laminates help protect your product
Laminates are used as extra layers to protect the raw material. For example, a foil laminate is often used in combination with PE or PET to protect flavour or prevent smell from leaking out through the film. Generally laminates are used:
- To keep the flavour and fragrance of the product fresh
- To protect the product from outside fragrances and flavours that could compromise it
Foils and variable gauges of PE, PET, Polyester laminates are commonly used to control these challenges.
Some raw material can damage the laminate so it’s important to know the chemical make-up of the product and choose an appropriate laminate. Different laminates are tailored to the specific needs of the product inside – there are lots of varieties available.
Water soluble film – a film that dissolves completely when put into water – is also available.
You’re contract packing company should be able to advise you on the right laminates to use depending on your raw material.
The step-by-step process – How does VFFS actually work?
- The machine is prepared by loading the appropriate film roll
- The film winds through a series of rollers and is shaped into a tube
- The tube is closed at the bottom by clamps creating the bottom of the bag
- The raw material is dropped into the half formed bag
- The bag is sealed at the top
- This seal forms the bottom of the next bag
- The bottom seal is cut in the middle separating the bag from the next one
The process happens quickly – approximately 30-40 bags can be produced per minute, working with a 65mm x 65mm bag and granular product.