How can bulk bag users reduce shipping costs?

The bulk density of your product determines the opportunity for shipping cost savings.

If your product is heavy enough to weigh-out a shipping container/trailer then, as we have seen in the last two posts, replacing wood pallets with a plastic channel replacement system or simply eliminating bottom support altogether can significantly reduce shipping costs.  Reducing the weight of packaging per shipment means you can replace the weight reduction with product thereby shipping out more product per container and reducing shipping cost per pound.

However, if your product's bulk density is such that you can't weigh-out a container/trailer there is an additional step you can take to minimize shipping cost.

Bulk Bag Densification Increases Payload

Light products such as wood flour, fluff carbon black, fumed silica and the like react favorably to certain types of densification.  This means that the payload of a given size bulk bag can be increased.  Increasing the bulk bag payload increases the amount of product that be shipped per container thereby reducing shipping cost per pound.

Low bulk density bulk solids tend to trap air between their particles. Depending on the particle shape it can be very difficult to remove the air while the bulk bag is being filled. Bulk bag filler densification systems are designed to remove the trapped air thereby densifying the product.

Some densification systems are more effective than others. Carefully matching the method of densification with the product characteristics can result in a significant improvement in packed bulk density thereby increasing payload.

Bulk Bag Densification Reduces Shipping Cost

As a starting point it is reasonable to assume that a densification system capable of maximum compaction should be able to increase payload weight by a minimum of 10%.

Control and Metering's experience is that payload increases of 20-30% are often achievable and in some cases as much as 40%+ more weight can put in a bulk bag that has been previously filled without densification or with ineffective densification systems.

Are Pallets Necessary?

Pallets are used to move heavy objects. Forklifts or pallet trucks are used to move them. In the case of bulk bags however, there is a built-in alternative to using a pallet or bottom located lifting device to move them: bulk bag lifting loops.

Every bulk bag has lifting loops that are designed to safely lift the bag and its contents. They can be used to move the bag from the filling station to storage into and out of a shipping container and everywhere in between.

So, technically, a bulk bag does not require a pallet or equivalent.

Checklist for Handling Bulk Bags Without Pallets

Bulk bag filling equipment. Before you can safely handle bulk bags without pallets you must ensure that your equipment is designed to allow the bag to be removed from it without a pallet. Bulk bag fillers can be designed to release the lifting loops while still supporting the bulk bag thereby allowing the bag to be removed by threading the fork tines through the loops. Note that you must have a forklift to remove the bulk bag from the filler - a pallet truck won't work.

Bulk bag design. The bulk bag loops must be 'cross corner' design and the must be designed to stand up right on their own. Both of these features make it easy to thread the fork lift tines through the loops without assistance. Cross corner refers to loops that are sewn on side of the bag and looped over the corner and sewn on the adjacent side. This provides a 'tunnel' for the forklift driver to aim for. Of course, the loops must stand up on their own to make the tunnel. This is done by sewing a strip of plastic within the loop to give it rigidity.

Sanitary considerations. Since the bottom of the bulk bag comes in direct contact with the floor - of your plant or warehouse and the shipping trailer/container - it is often advisable to add a protective flap across the entire bottom of the bag to minimize contamination and provide an extra layer of fabric for added robustness. The flap is sewn along one edge, drawn across the bottom of the bag and attached to the opposite side using Velcro or loops and ties.

End user capabilities. While shipping bulk bags without bottom support has many benefits for the producer, it is a catastrophe for an end user without a forklift. Your customers have to be prepared, willing and able to work with your product in bulk bags without pallets.

Shipping Bulk Bags without Pallets - Is It Really Feasible?

Short answer: yes. Although a small percentage overall, there are many bulk bags being shipped without pallets. For example, export shipments of various products that travel via shipping containers are often shipped without any kind of bottom support. In North America, one of the resin industries converted from boxes to bulk bags now all domestic production of this type of resin is shipped in bulk bags without bottom support.

Palletless Bulk Bags - Benefits

Shipping without a pallet or any bottom support is a lucrative proposition. A number of operatic cost saving opportunities immediately occur:

1. Eliminate pallet cost.
2. Reduce shipping cost. Removing the weight of the pallet from each shipped package means you can increase the payload weight of each bulk bag. This can significantly reduce the shipping cost per pound of product.
3. Reduce handling labor. Not having to manage the handling of heavy pallets increase productivity and reduces packaging labor cost per pound.
4. Increase warehouse efficiency. Not having to store pallets can significantly increase available warehouse space.
5. Eliminate border crossing delays. Borders crossing delays often occur because palleted shipments may be inspected. Additional time (money) can be lost if documentation has to be resubmitted or modified.
6. Improve sustainability.  Eliminating pallets and any kind of bottom support clearly improves sustainability by reducing the use of material and waste.

Shipping bulk bags without bottom support is feasible, is already being done and can dramatically reduce operating costs.

Wikipedia describes ISPM 15 as the:

"International Phytosanitary Measure developed by the IPPC that directly addresses the need to treat wood materials of a thickness greater than 6mm, used to ship products between countries.  It affects all wood packaging material (pallets, crates, dunnage, etc) requiring that they be treated with heat or fumigated with methyl bromide and marked, often branded, with a seal of compliance. "

Wood Pallet Cost Rising

As a result, the total cost of wood pallet usage has escalated dramatically.  Not only has the cost of ISPM 15 compliant pallets increased, shipping documentation preparation and possible border crossing delays consume additional time and resources. 

That coupled with historic problems related to mold growth, damage to shipped product from pallet defects (splinters, nails, etc.) and the outright refusal of some countries and/or customers to accept wood pallets has caused a strong desire to find a wood pallet alternative.

Bulk Bag Solution

If you ship your product in bulk bags there are two solutions that Control and Metering can recommend:

1. Plastic pallet replacement channels.
2. Shipping bulk bags without any kind of pallet-like support.

Plastic Pallet Replacement Channels

We have had extensive experience with BagPal channels.  These are designed to slip into sleeves attached to the bottom of specially made bulk bags allowing the bulk bag to be handled by a forklift just like a bulk bag on a wooden pallet.

BagPal channels are robust, compare favorably price-wise with treated wood pallets and can be reused and recycled.

Also, they provide a traditional means of moving bulk bags with a forklift - any forklift with standard tines can be used to move a BagPal equipped bulk bag.

Plus, a pair of BagPal channels weighs less and is much smaller than a wood pallet.  These features provide two significant financial benefits:

1. Reduce shipping costs by increasing your bulk bag payload by the difference in weight between a pallet and the channels - roughly 30+ lb. Higher payload per bag equals more product in a truck or container.
2. Increase warehouse efficiency by using MUCH less space to store empty channels vs. empty pallets.

Bulk Bags Minus Bottom Support

Bulk bags can be shipped without bottom handling support of any kind.  This has been done in a number of industries for both domestic and export delivery to customers.

Without bottom handling support bulk bags must be lifted using their loops.  Preventing damage and contamination of the bag bottom is also required.

Specially designed bulk bags with unique lifting loops and protective bottom panel barriers solve these issues. 

Shipping bulk bags without bottom handling support is a topic by itself and will be the topic of next week's blog post.

Ever heard of a 'porthole' style bulk bag?  If you haven't we'll fill you in.  If you have, and you're having problems with them, we'll list what you need to know.

A porthole bulk bag has a porthole in its bottom.  A flat bottom liner is inserted into the bag and filled.

Porthole syle bags are discharged using a bulk bag unloader that features a 'knife' to cut the liner through the porthole. 

1. Stuff the liner properly.  One of the key benefits of using porthole style bags for in-house use (you fill and empty the bags within your plant) is that the outer bulk bag can be reused by simply discarding the old liner and stuffing a new one into the bag.  However, unless the liner is properly reinserted, twists or folds can occur that will prevent the liner from being easily cut by the discharger.  This can lead to shredding of the liner - resulting in downstream product contamination - or a badly twisted or folded liner can seriously impede or even prevent easy product discharge.  Work with your bag/liner supplier to develop a Standard Operating Procedure to ensure the liner is properly inserted.

2. Keep the knife sharp.  This advice might seem counter intuitive from a safety perspective.  However, unless the bulk bag discharger knife is sharp you run the risk of tearing the liner instead of cutting it cleanly.  Tearing through the liner can sometimes result in shredding, which in turn can deposit liner material in the product flow.  Product contaminated with liner shreds is a serious problem to be avoided at all costs.

3. Use the bulk bag discharging equipment properly.  A knife style discharger will have a particular procedure that needs to be followed to ensure trouble free cutting of the liner and complete discharge of the product.  Make sure you confer with your equipment supplier to develop a proper procedure for unloading porthole bulk bags.

There is a surprisingly high number of dry bulk solid ingredients that will 'set up' (solidify) when stored in a container.  This can cause significant problems when the container is emptied... the problem being that if the ingredient has solidified enough it simply won't flow!

In the case of bulk bags filled with solidified ingredient, we have encountered many plants who have devised their own solutions to this problem:

• Hitting the bulk bag with hand held solid objects (pipes, etc.)
• Bouncing the bag on the floor with a forklift
• Driving the bag into a wall or column with a forklift

As you can imagine these so-called solutions are usually somewhat less than effective and are most certainly sub-optimal - most importantly they are unsafe.

What to do?

Pre-condition the bulk bag by using a device such as the Bag Squeezer.  Its name nicely describes its function!

By safely breaking up the ingredient prior to attempting to discharge it, productivity will be improved, dusting will be minimized and safety will be dramatically enhanced.

Looking for ways to improve the sustainability of your bulk bags?

How about reducing their size?

How do you do that?

Do a better job of densifying your product so that it takes less volume for a given weight... and use a shorter bag!

Ideally, the product you put in your bulk bag should be at its maximum packed bulk density when it leaves your bulk bag filler.  If it's not you are using a larger bulk bag than necessary and, more importantly, it may not be safe.

Not all bulk bag fillers do the same job when it comes to compacting or densifying your product.

At Control and Metering we use a 'rule of thumb' that for every 10% you can reduce the height of your bulk bag, the cost reduces by 5%.

So if you can do a better job of densifying your product while it's being filled you're not only lowering your packaging costs you're also improving your packaging sustainability.

A VERY nice win-win!

Unfortunately, Dusting is a Common Problem

While bulk bags can be the most economical package for shipping semi-bulk quantities of dry bulk solids, they often get a bad rap from end-users because the process of unloading them can be dusty.

Excessive dusting during discharge obviously causes a mess requiring additional clean up labor.  However, it can cause significant profit reduction because every pound of product that lands on the floor reduces ingredient yield and increases input costs.

Dusting Can Be Costly!

We know of a food manufacturer whose bulk bag discharging stations create a lot of dusting during unloading.  A plant visit confirmed the mess made during bulk bag discharging, but curiously their floors are always spotless!  

The plant has hose bibs EVERYWHERE, which encourages cleaning.  Seemingly a good thing.  

However, a thorough analysis of their ingredient yield showed that they were losing approximately $300,000.00 annually due to poor yield: TONS of product - along with a good chunk of profit - were being washed down the drain!

While it's true that not all of that waste was directly attributable to dusting from bulk bag dischargers, most of it was.

So, not only is dusting during bulk bag unloading a nuisance and housekeeping issue, it can quickly affect - negatively - the bottom line.

What can be done?

1. Training.  The biggest issue we see with the use of bulk bag dischargers is that operators are not following the manufacturer's operating instructions.  Regardless of the equipment used to unload bulk bags, if it is not used properly optimal dust containment cannot be achieved.  Left to their own devices operators will quickly figure out the easiest way to get product out of the bag - and that often leads to unecessary dust emissions.  Easy operation sounds like a good thing, but the reality of discharging bulk bags is that they require some effort to use properly.  Work with your bulk bag discharger vendor to fully understand how their equipment should be used to best effect and then train and supervise your operators accordingly.
2. Bulk bag design.  We often see situations where fine product sifts through the fabric of bulk bags.  If that sounds familiar your ingredient vendor should be willing to work with you to provide a bulk bag that eliminates this problem.  The easiest solution is to used coated bulk bags that feature a film of polypropylene bonded to the inner surface of the bag fabric.  This should cure most sifting problems.  However, if a coated bag isn't enough your vendor should be using a separate polyethylene liner.
3. Bulk Bag Discharging Equipment.  Bulk bag dischargers come in many configurations.  Some are better than others when it comes to dust containment.  Look for designs that allow easy  and safe access to the bag outlet spout while keeping it enclosed in a hopper that can be connected to a vacuum dust collection system.  However, not all of these designs are created equal!  If the hopper that is under negative pressure is filled with product during discharging, dusting will still be a problem when the hopper door is opened and product that has adhered to the inside of the door drops on the floor.  Ideally, the outlet spout of the bulk bag should protrude out of the hopper during discharge so the only time the hopper sees dust is during the initial stage of product flow and perhaps at the end of the discharge cycle.  Ergonomics are also a key criteria when selecting a bulk bag discharger.  As mentioned above, you don't want your operators circumventing Standard Operating Procedures and creating excessive dusting because the bulk bag discharger is too difficult to use properly.  Carefully evaluate dust containment features and ergonomic design when selecting a bulk bag discharger.

Before we discuss all of the considerations necessary to design a successful high-speed bulk bag filling line, let's first agree on what "high-speed" means!

If you are currently filling four bulk totes per hour, 10 bags per hour may seem to be high-speed.  After all, that's a 250% rate increase!

If you're filling 10 bags every hour, an automated bulk bag filling system that produces 15 - 20 FIBCs in the same time it takes you to fill 10 is a big deal.

However, at least for the purpose of this article, we're going to define high-speed bulk bag filling as producing 30 or more filled bulk bags per hour.

Yes, that's a lot, but it can be done consistently, with excellent weighing accuracy and such a rate can be achieved while producing stable - safe - bulk bags.

Sequence of Events

What happens when filling bags at a total rate of over 30 tons - 60,000 lb - per hour?  Well, exactly the same things happen as when filling 3 bags per hour, except they happen in a much shorter period of time.

Here is the timing chart for a bulk bag filling system designed to achieve a rate of 30 bags per hour:

Those are the same five tasks that are required to fill virtually any bulk bag at any rate.  However, as you can see and as we predicted above, the duration of each task is very short if we want to achieve a total cycle time of only 120 seconds!

High Speed Bulk Bag Filling - Critical System Considerations

Bulk Bag Design

The design of your bulk bag must support the overall system required to achieve a high speed bagging rate. 

For example, is the design of the loops compatible with the equipment such that they will be easily released and not hang up when the bag is automatically removed from the filling machine? 

Is the diameter of the inlet spout big enough to accommodate the filling machine fill head - that has been designed to achieve the instantaneous flow rate necessary to fill the bag in the required time?

Bulk Solid Handling System

The system that moves or conveys the dry bulk solid powder, flake, granules, pellets, etc. to the bulk bag filling system must be sized to maintain the gross throughput of the system.  In the case of 30 - one ton bags per hour, that is 60,000 lb per hour.

Instantaneous Bulk Solid Flow Rate

Ensuring that the bulk material handling system upstream of the bulk bag filler can maintain a continuous rate of 30 tons per hour does not necessarily guarantee that bulk bags can be filled to match that rate.

As can be seen in the timing chart above, over half of the cycle time is consumed by tasks unassociated with actually getting the bulk solid product into the bag.

In our example there is only 55 seconds allowed to deposit 2,000 lb of product into the bulk bag.  That means the required instantaneous bulk solid flow rate is roughly 130,000 lb per hour!

If the bulk bag filling machine performs weighing during this time, a 'dribble feed' task is required.  That means that part of the 55 seconds alloted to filling the bulk bag with product is used to dribble the last, say, 50 lb of product into the bulk bag to maximize weighing accuracy. 

Typically, for it to be effective, the dribble feed time is 10-15 seconds in duration.  That leaves only 40 seconds to fill 1,950 lb into the bag.  In that case the instantaneous fill rate is over 175,000 lb per hour!

Surge Capacity

As described in the above section, the bulk bag is actually being filled for only a portion of the total bag fill cycle time.  The rest of the time - called overhead time - is taken up by other tasks. 

During the overhead time bulk solid product cannot flow into the bag.  However, since our bulk material handling system continuously feeds 60,000 lb per hour to the bulk bag filling system, the product conveyed during the overhead time must be stored above the bulk bag filler. 

Typically, a surge hopper or storage vessel of some kind is used to hold the product conveyed to the bulk bag filler during the overhead time.  Calculations can be made to determine the vessel volume necessary to hold the product - commonly called surge capacity.

Bulk Bag Filling System

The bulk bag filling machine must be designed to accomplish the tasks in the time alloted - while maintaining acceptable weighing accuracy and producing stable and safe bulk bags.

Features such as automatic loop release, automatically movable loop attachments, automatic bag removal, etc. are required.

However, the most critical consideration is that because each task duration is so short, each aspect of the bulk bag filler's design must be optimized to not only operate quickly, but to perform its function properly in so short a time.  Weighing accuracy of +/- 1-2 lb and bags that have been filled to their maximum bulk density can be achieved when filling bulk bags in excess of 30 per hour.  However, specialized designs are required.

Filled Bulk Bag Takeaway

Removing one filled bulk bag every two minutes from the bulk bag filling system is no easy task.  Forklift traffic patterns must be considered as well as the round trip distance from the filling system to/from the warehouse storage point or loading dock.

Pushing The Envelope

Bulk bag filling rates in excess of 30 tons per hour can be achieved.  Filling machines that perform weighing can be made to fill up to 35 bags per hour.  Pre-weighing - weighing the product in a vessel above the filler and dropping the 'shot' into the bag as quickly as possible - can reduce the bulk bag filling cycle to the point where it is possible to produce over 40 bags per hour.

As can be seen there are many considerations that must be addressed when implementing a high speed bulk bag filling system.  Careful work conducted in partnership with the bulk bag and bulk bag equipment vendors is a must to ensure success.

This article was written by Dan Schnaars, President of Ameriglobe LLC, one of North America's premier FIBC manufacturers.

When to Use Liners vs. Laminated Fabric vs. Fabric for your Bulk Bags

When you are in the process of designing your bulk bag packaging specifications, one of the key issues to consider is the kind of environmental protection the bag must provide to your product.

The best answer for you can sometimes be quite detailed.  Here we will consider the three basic types of protection.

Uncoated or Breathable Fabric Bulk Bags.

Bulk bags are made of woven polypropylene. While the weaving makes a fabric that appears quite solid, it is, in fact, breathable.  Air and ambient moisture pass quite easily through plain fabric.  Dusty products contained within can ‘dust' through the fabric and/or the seams of the bag.  For the majority of applications, breathable or plain fabric does not provide enough containment.  Any product contained in a breathable fabric bag will likely reach ambient humidity levels within a few days.

But, some products such as soy bean seeds or peanuts require a breathable container.  The airflow retards germination and mold and is, therefore, a necessary feature.  Many minerals travel in breathable fabric bags due to cost.  The mineral products often have a low cost per ton and the packaging cost is quite a significant factor in the final product cost.  Coating the fabric does add cost to any fabric.

Laminated (coated) Fabric Bulk Bags 

The most common method of environmental protection for your bulk bagged product is to use a bag that has a thin layer of film laminated to the inside of the bag.  This lamination eliminates most of the air flow through the bag. Most products travel well in this type of bulk bag.  Dusty products do not pass through the lamination and dust from the outside does not enter the bag through the weave.  Ambient humidity transfer is greatly limited by the lack of air flow as well.  If small amounts of sifting are not an issue and small amounts of contamination are not an issue, then this bag is most often the right choice.

Lined Bulk Bags

The need for extreme cleanliness, moisture control, or oxygen flow is what generally dictates the need for liners. 

Contamination Issue - Bulk bags are made from a manual sewing process. The fabric itself is often charged with static electricity that causes small pieces of sewing thread to cling to it.  Some companies are vacuuming the insides of the bag and working in clean environments, but this is only a reduction of the opportunity and amount of contamination.  Over the course of time, a loose thread or two will occur.

Sifting issue - In the sewing process, a needle punctures the fabric and carries a thread through the hole with it.  In order to do this the needle has to be bigger than the thread it leaves behind. Powders will often pass through this extra space.  To reduce this, bulk bag manufacturers offer to add ‘sift-proofing' materials to the seams.  Again, while this greatly reduces the amount of product that can sift through the seams, it can never be 100%.  If it were, then bulk bags made in this way would be able to hold water and not a single one can do this.

Only the proper use of a liner can ‘100% guarantee' that there will be NO contamination in your product.

Moisture control - If sifting cannot be prevented, then you can easily see why strong moisture control cannot be attained without a liner as well. The selection of the specific liner is just as important as the selection to have any liner at all. 

Most applications will use a 2 to 3 mil polyethylene liner.  This liner will work for almost all food applications, general moisture control, all sifting and contamination issues.

Specialized liners can be used when there is an absolute and special need.  For absolute moisture control, a liner with foil laminated to it can be used.  Liners with special gas transmission rates are selected when odors need to be contained or oxygen must be kept out.

Hazardous materials almost always require the use of a liner.

Liner attachments - The final piece to this discussion would be the connection between the liner and the bag itself.  Although many companies simply put the liner into the bag with no connection, this will often create problems for the end user during the discharge process. 

If the liner is unattached, it simply falls out with the product and becomes a contaminate in the receiving hopper.  Liners should be physically attached to the bag so that it will stay in the bag as the product leaves the bag.

There are three methods for attachment; sewing, tape tabbing and gluing.  Different products need different strengths of holding power. 

Some products like pellets will flow very easily from the bag.  It takes very little attachment support to hold the liner within the bag.  In this case, any of the attachment methods will work well. 

Other products tend to clump together such as powders.  These products can grab the liner more intensely.  It takes much more holding power to keep the liner attached to the bag. 

While opinions may vary, the method of attachment that involves the greatest number of square inches of the liner for its strength is a good gluing method.  Done well, this method can generate the most holding power possible for the most difficult applications.

Whatever your need, when you are designing a bulk bag package, involve your bulk bag supplier in the decisions.  They should be able to recommend the best product protection for your application.

-Dan Schnaars, President Ameriglobe LLC

Many producers of dry bulk solids, who have traditionally shipped their products in drums, boxes or rigid totes, want to take advantage of the financial benfits of converting to bulk bags. 

However, it is often difficult to convert every customer at once.  That means that for at least some period of time bulk bags and the legacy package(s) must be filled.

The problem is how do you handle having to fill multiple packages with multiple packaging machines? 

Changeover can be a significant challenge particularly if your current packaging machine is not portable.  Production scheduling and the time required to simply change from the existing packaging machine to the bulk bag filler can be barriers that prevent companies from benefiting from bulk bags.

What's the answer?

A multiple-package filling machine.  Purchasing a bulk bag filler that also fills drums or boxes or rigid totes - or ALL of these packages - is feasible and economically very attractive.

Filling multiple packages on one machine requires more up front capital as compared to a machine designed to fill only bulk bags.  However, the operational benefits of using a single machine that automatically changes its configuration to fill up to four different packages are significant.

Just think, no delays for changeovers AND you can satisfy those customers who have not yet converted to bulk bags.  A good deal I think.  Plus, there's the financial benefits that immediately hit your bottom line from converting to bulk bags... but that's another story!