All Member Forum

 View Only
  • 1.  Stacking Height Issue

    Posted 10-30-2023 11:49 AM

    Dear Team,

    I currently have a rounded bottle with diameter 80.5mm, and bottle height is 300cm. The bottle weight is 32 grams, and the filling level is 1500ml. We apply only external shrink with configuration of 3*2 bottles (6 bottles per shrink) and the dimensions L*W*H of the configuration are 187.5mm281.3mm300mm. The current pallet factor for 120cm100 cm pallet is 22 shrinks per layer 4 layers (88 shrinks), and I was requested to have 5 layers instead of 4 layers. Pallets were prepared with 5 layers but I had static load faliure in the second and third layers. Are there any options to try to have the 5 layers successful? How can I calucalte the load on the bottles at the first layer of the pallet? Please find below photos for failed trial. 



    ------------------------------
    Omar Mohamed
    Packaging Development Manager
    Beyti- An Almarai subsidary
    Cairo
    010 96355560
    ------------------------------


  • 2.  RE: Stacking Height Issue

    Posted 11-05-2023 07:09 PM
    Hi Omar.

    From the photos, it is hard to see if you are using layer pads, including between the pallet and the first layer. Can you confirm? That will help spread the load evenly. You also might want to try corner posts before stretch wrapping the pallet.
    Is there any way you can measure (or ask your supplier about) the top load of the bottles - ASTM D2659 or equivalent?

    JFG

    ---------------------------------
    Jean-Francois Guillerez CPP, Fellow
    Professor, Packaging
    Conestoga College Institute of Technology and Advanced Learning
    Cambridge ON
    Canada
    ---------------------------------





  • 3.  RE: Stacking Height Issue

    Posted 11-14-2023 01:51 PM

    To all,

     

    I apologize for the late reply, however here is feedback from one of our packaging SMEs.

     

    Hard to say with just pictures... it seems like the 6 pack shrink is not robust enough to hold its shape or perhaps the bottles are not pressurized and that's why they are failing.

    Load calculation is easy... he just needs to calculate the area of each closure times the number of bottles per layer.  The pressure on each layer is the weight of all bottles on top of the layer x the contact area of all closures divided by number of bottles supporting the load.   Then divide that resultant individual pressure by the area of a single closure and you'll get the force (weight) on that individual bottle.

     

    Hope this helps

     

    Regards,

     

     

    Velma R. Thomas, MBA, CFS

    Manager, QSE Authorizations

    Mobile: 404-210-8116

    One Coca-Cola Plaza, Atlanta GA 30313

    email: vthomas@coca-cola.com

     




    CONFIDENTIALITY NOTICE
    NOTICE: This message is intended for the use of the individual or entity to which it is addressed and may contain information that is confidential, privileged and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any printing, copying, dissemination, distribution, disclosure or forwarding of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and delete it from your system. Thank You.

    Classified - Confidential






  • 4.  RE: Stacking Height Issue

    Posted 11-06-2023 07:01 PM

    Good day Omar:

    I thought that I may be of some help with regard to your pallet pack situation. I will start with several questions and then make an observation or two.  Forgive me if you have already addressed these questions internally or have already investigated the items below.

    • Did the static load failure occur with one or more pallets stacked on top of the pictured pallet or did the failure occur as a result of building and warehousing the single, pictured pallet?
    • Did you observe any failure of the individual packages such as crushed or uneven bottle necks, bottle body wall collapse or bottle bottom roll-in or other failure?
    • Jean-Francois had a good question regarding the use of layer pads.  If layer pads are used, are they thick and/or rigid enough to resist the closures of the bottles from embedding in the layer pad material? 
    • How will the finished pallets be warehoused, as single pallets on a warehouse floor or within a warehouse racking system, as stacked pallets? If stacked, how high a stack? 
    • How will the finished pallets be shipped to your customers, over the road trucks, railroad, a combination of truck, rail, maybe overseas shipping?  Warehousing and the mode of transportation will certainly be factors in how the total pallet package should be configured.
    • Have you looked at the potential use of a pallet top cap to aid in keeping the cases in the top layer in place and positioned correctly over the next layer down?
    • While I am not an expert in stretch wrapping, there may be value in evaluating the wrap mil thickness and position on the wrap as it is would around the pallet.  there may be a more optimal material to sue and manner in which that material is wound around the pallet. 

    Jean-Francois had a good question regarding layer pads.  I would add that since your package has a smaller closure diameter than the diameter of the bottle, any layer pad would need to be thick and/or stiff enough to resist the closure top from being embedded into the layer pad.  Corner posts could also be helpful with improving overall pallet rigidity and resistance to layer shifting. With respect to container strength, it is always a good idea to be aware of the axial (top or crush) load of the package as well as the resistance to bottom roll-in and dent resistance of the container body.

    Perhaps I can offer a few observations:

    • From the pictures you provided, it appears to me that primarily the second pallet layer has shifted.
    • In my experience with glass, plastic and metal food and beverage packaging, pallet failures as you encountered were generally not due to the axial strength of the individual container.  Often, the type of pallet failure shown was due to an offset load situation.  In those cases, either the individual (3x2 = 6 bottle) cases were stacked improperly and/or a pallet was stacked on top of the failed pallet too far to one side.  In turn, the lower pallet would fail at the lower layers, but usually not the bottom layer. 
    • In a situation that may have involved pallet offset, a common indicator was the existence of container failure somewhere along the vertical body and/or neck (if a plastic bottle).  It was found that the container failures were offset failures (the package being exposed to an offset vertical force greater than the package resistance to that force).  Container resistance to offset force is generally much less than the same container's resistance to direct vertical forces (axial load or crush as stated previously).

    Overall, it is my opinion that your pallet has experienced an offset load condition.  The best way to address that condition is to improve the pallet layer positioning and between layer padding and to increase the rigidity of the pallet through the possible use of corner posts, a top cap and optimized stretch wrapping.



    ------------------------------
    Bill Smialek
    Consultant
    Fox River Grove, IL
    Ph: 414-520-8749
    E-mail: smialek3@sbcglobal.net
    ------------------------------



  • 5.  RE: Stacking Height Issue

    Posted 11-07-2023 09:02 AM

    Omar,

    I will agree with the points from JFG and Bill. It appears to be an offset failure of the load. Something that I am also noticing that has not been mentioned is that the load appears to have a significant tension on the stretch wrap. That is a key factor for creating bottle crushing on pallet edges, because it shifts the vertical load to a diagonal load on the bottle and often pulls the bottles inward, especially because the bottle neck is thinner than the overall bottle diameter.. This will create an offset pallet that can certainly experience these failures. Also be careful of using layer pads that are too large - if the corners stick out too far from the load then the stretch film (especially if the pad is thin or the film has high tear resistance) will grab those corners and pull up or down, which will also pull the bottles off of their ideal position and create an offset load failure. Per the other comments, corner posts and a top/bottom tray that is designed to the load and strapped down will also help to disperse the force of the load to the entire load instead of just on the corners.

    I would get my hands on a LanTech CFT-6 device and optimize your load wrapping to prevent this, but have enough strength to contain the pallet. A good starting value is probably 4-7 lbf on the top, middle, and bottom of the load, but you will need to optimize by trialing based on your film, load, and process. You can always make adjustments by removing layers of film (ideally at specific locations on the load) and reducing machine tension.

    Hope that helps.

    Aaron



    ------------------------------
    Aaron Stauble CPP
    Packaging Engineer
    The Gorilla Glue Company
    Cincinnati OH
    (513) 869-9428
    ------------------------------