31/07/2017: The six guidelines you need to specify a bulk bag filler

by David Boger, Vice President of Flexicon Corporation

Exponential growth in the use of bulk bags has spawned an entire manufacturing segment dedicated to producing specialised equipment that not only fills and discharges bulk bags, but offers various degrees of automation and integrates filling and unloading operations with upstream and downstream equipment

As the number of equipment options increases, so should the ability of the ‘specifier’ to evaluate stand-alone equipment and integrated systems against current and anticipated needs. Here I address the ‘filler’ half of the bulk bag handling equation, offering the six most important parameters to consider when satisfying any individual bulk bag filling requirement with top efficiency and cost effectiveness.

1) Anticipate maximum capacity
The difficult but critical question: How many bulk bags will you need to fill per week during the useful life of your next bulk bag filler?

With few exceptions, buying a more costly filler with higher capacity than you now need will be less costly than replacing a filler you outgrow, unless that filler can be retrofitted with performance enhancements at a later date.

Capacity requirements run the gamut, from one bag per week to 20 bags per hour. Where your volume falls should, in part, influence your decision to specify a manual, semi-automated or fully automated machine. Generally speaking, the more manual the filling operation, the more output is subject to variation.

When gauging the capacity and payback of manual equipment against automated equipment, you need to determine the average pace at which operators can attach, detach and cinch bag spouts, remove filled bags, load pallets and conduct all other filler-related operations.

When estimating the time allocated to these manual functions, it is advisable to anticipate a pace that an operator can realistically maintain throughout an entire shift while avoiding fatigue or injury.
 

Figure 1.
Image credit: Flexicon

For the lowest volume applications, basic filler operated manually will maximise your return on investment. One example is a medium-gauge Twin-Centrepost™ filler (FIG. 1) that offers the structural integrity of four-post fillers but at significantly lower material and fabrication costs and with less weight.

This two-post design also affords unobstructed access to the bag spout and loops, facilitating rapid manual insertion and removal of bags. This class of filler is typically equipped as standard with fill head height adjustment via fork truck to accommodate all popular bag sizes, a feed chute vent port for dust-free air displacement during filling, and an inflatable cuff to seal against the bag inlet spout and ensure it does not collapse on itself during filling.

Limited performance options, which can be added initially or retrofitted, include an inflator to expand the bag prior to filling, and a programmable scale system with flow control valve for filling by weight. 

 

Figure 2.
Image credit: Flexicon

The cost of a scale system can be avoided by placing the entire filler onto an all-purpose plant scale, providing the filler is properly equipped for in-plant mobility (FIG. 2).

If a forklift is unavailable to remove filled bags, as is required by the above-mentioned fillers, configurations are available with a three-sided base that provides access from the open side using a pallet jack (FIG. 3).

This low-profile configuration can also be utilised to conserve height in low headroom applications. The time required to prepare empty bags for filling, and to remove filled bags from beneath the filler, can have as much or greater influence on maximum filling capacity than the rate at which material enters the bag.

As such, adding a roller conveyor allows filled bags to be rolled out of the filling area for spout cinching and pallet/bag removal while another bag is being filled. Adding such a conveyor system, however, generally requires a filler with rear posts (FIG. 4) and a cantilevered fill head equipped with hooks that release bag loops automatically, so if higher capacity is in your future, a rear post configuration may be your best choice today. 

 

Figure 3.
Image credit: Flexicon

Increasing the capacity of systems equipped with roller conveyors to the next level generally entails adding an automated pallet dispenser (FIG. 5) which places pallets and slip sheets onto the roller conveyor upstream of the filling operation, further reducing the time required for each filling cycle by limiting manual operations within the filling station exclusively to loading an empty bag.

To further reduce the time needed to attach the spout of an empty bag to the filler, this Swing-Down® filler (FIG. 6) lowers the entire fill head to within an arm's length of an operator standing on the plant floor.

Further, it pivots the bag spout into a vertical position, enabling the operator to connect the spout of an empty bag to the inflatable bag spout collar in several seconds, after which the spout pivots back to horizontal, the entire fill head returns to fill height, the bag is inflated, and filling commences. 

 

Figure 4.
Image credit: Flexicon

Additionally, when the bag reaches its target weight, the bulk material delivery system deactivates automatically, the spout collar deflates, the fill head raises to decouple from the spout, and the powered roller conveyor sends the bag downstream of the filling area--automatically, rapidly and safely.

2) Evaluate safety against manual operations required at any given level of capacity
With manual and semi-automated filling operations, the potential for worker fatigue and injury can increase according to required output per shift, relative to the type of bulk bag equipment specified. 

 

Figure 5.
Image credit: Flexicon

Consider that the connection points of a conventional filler are often beyond the reach of most operators, even when short bags are being filled. But adding the height of a roller conveyor to the height of a bulk bag to the length of its bag loops puts the connection points for bulk bags of only 122 cm in height at approximately 213cm above the floor!

This requires an operator to stand on a platform, a ladder, or on the roller conveyor while straining to reach overhead spout connection points and inserting hands between temporarily disabled moving parts. Difficult-to-reach spout connection points can therefore compromise safety as well as capacity—two problems that can be solved with the addition of a fill head that lowers and pivots to the operator at floor level.
 

Figure 6.
Image credit: Flexicon

Repetitive manual tasks such as releasing bag hooks, placing pallets on a roller conveyor or actuating bulk material delivery, also increase the potential for error and injury, justifying semi- or fully automated equipment for all but the lowest volume applications.

Read the remaining guidelines in the full article, HERE.

Visit the Flexicon website, HERE.

 

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