Principles of FIBC Bulk Bag Filling: Design & Handling
“As more products are supplied in FIBCs, questions & concerns are being raised about all aspects of the FIBC System of Packing.”
- Suppliers/Manufacturers of products to be filled into FIBCs.
- End Users/Buyers of products supplied in FIBCs.
- Companies using FIBCs as a handling unit within their own plant.
- Custom Packers receiving products in bulk for packing into FIBCs.
- Transportation/Shipping/Storage companies handling FIBCs.
FIBC Design: Sizing the FIBC
- The weight of the product in the FlBC and its tamped bulk density.
- The internal dimensions of the shipping container or road vehicle where the filled FIBC is to be placed.
- The net filled height of the FlBCs after filling.
- For safe stacking of FIBCs it is not advisable to stack bags two high if the bags are over 5’ high and three high if they are over 4’ high – regardless of whether they are on pallets or not. FIBCs should not be higher than twice the base plus width.
- The filled height of product in the FIBC after filling can vary considerably depending on the type of filling machine used and the characteristics of the product. It is therefore important to get the product tested on the selected filling machine before ordering FlBCs. Bulk bag filling machines that have the capability of densifying the product during filling, save on FIBC height and make a safer and more stable FIBC for stacking and handling.
Lifting Loops, filling Spouts & Outlets
“The choice of FIBC is critical, both with regards to design & size as the most expensive part of an FIBC packaging system is the FIBC itself.”
- Flat Bottom
- Conical Bottom
- Hygiene Flaps and Hygiene System
- Fully Opening Bottom Bags
FIBC Construction & Quality
Bulk Bag Pallets
- The correct size of pallet should allow the rounded section of the FIBC to overlap the edges of the pallet so that when two palletized bags are placed side by side, the bags touch and not the pallets. This increases stability of the bags when packed in containers/trailers.
- The FIBC should be positioned as close to a central position on the pallet as possible, especially after filling. A wide range of mechanical devices to assist the fork lift truck driver to achieve this are available as well as side shift on the truck itself.
- If the FIBCs are to be stacked, close slatted pallets, both top and bottom should be used to stop ‘pinching’ of the bag by allowing the top and the bottom of the FIBCs to protrude through the slats. These tend to be expensive and may only be financially justified for ‘in plant’ use unless return of them can be guaranteed.
Particle shape as well as size plays an important part in the time it takes to remove entrained air. Plate shaped particles, of clays for instance, take three to four times the amount of vibration to remove entrained air than a similar sized round particle. Granular particles will lose their entrained air quickly under their own weight. The larger the granule the shorter the time it takes to get to a tamped bulk density. Even then vibration will insure added stability is achieved. Vibration will only act on the weight of the material above the weight of the vibration platform. Therefore, vibration should not be commenced until a minimum weight of 450 lbs. is in the FIBC.
“During the development pf FIBC filling machines, certain basics have been identified that must not be overlooked when filling FIBCs.”
Principles of Bulk Bag Filling
- Correct position of empty FIBC in relation to machine base – All woven polypropylene bags will stretch to some extent during filling when hung by their loops. The FIBC should be positioned so that the seams of the FIBC can stretch down during the filling cycle, with the actual comers of the bag only touching the base when the fill cycle is complete.
- Base Vibration for Densification – The bulk density of the product in the filled bag should be as near as possible to its tamped bulk density. This should be achieved while the FlBC is awaiting removal from the filling machine.
- Fill Rate Control and Displaced Air Exhaust – Complete control of the product passing through the filling head must be maintained to facilitate a steady filling rate. The filling head must also allow for the exhaust of displaced air to prevent dust and pressurization of the FIBC during filling.
- Liner Inflation & Attachment to the Filling Head (Slip Seal) – For FIBCs with liners, inflation is particularly necessary prior to filling. The liner needs to be sealed to the filling head to insure there is no dust release. However, during inflation and filling the liner must also be free to move inside the FIBC and take up the shape of the bag without stretching.
- Robust construction – to insure long life and protection from potential damage from fork lift trucks.
- Operator Access – Ease of access to:
- Attach the loops to the FIBC Support Arms.
- Connect the Filling spout/liner to the filling head.
- Disengage the Filling Spout/liner from the filling head.
- ‘Tie off’ the filling spout. The operator should be able to carry out all of these functions at shoulder height without the need to climb on the machine.
- Electrical controls – preferably microprocessor based (compact) and easily accessible by the operator. All bag filling functions should be able to be performed manually (as required by the operator) and automatically (once the filling cycle is initiated).
- Pallet Magazine/Stacker – Several pallets can be placed ready for the filling operation to commence. This equipment then selects a lone pallet from the stack to be sent to the filling machine.
- Slip Sheet Dispenser – A slip sheet is then placed on the pallet automatically prior to filling.
- Automatic Bag Loop Release – Once the bag is filled it is automatically released from the filling machine ready for automatic removal. Take Off/Accumulation Conveyor – The filled bag is then conveyed away, allowing a new bag to be placed ready for filling.
- Spinning Head – This is an attachment to the filling head suitable for use with ‘baffle’ bags and granules where vibration alone is not capable of both de-aerating and dispersing the product. The Spinning Head disperses the product stream as it enters the bag to achieve an even fill.