unit load design: commercialization · 2019. 3. 19. · distillation page 08 box edge loading is a...
TRANSCRIPT
Unit Load Design: Commercialization
National Wooden Pallet & Container Association
WelcomeMessage
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Unit Load Design is the recognition that the cargo sitting on a pallet supports some of it’s own weight.
Kristen DeLack, PEStructural Engineer
• Introduction• Commercialization• Distillation• Question & Answers
Outline
Types of unit loads
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Roadmap
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Extensive Testing
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• Nearly three years of testing unit loads of boxes is wrapping up.
• Long-term creep tests will be complete in another two months.
• Exploratory testing.• Full scale lab testing of stringer and block
pallets with unit loads of boxes.• Box crush testing.• High humidity testing.• Vibration during transportation tests.• Stretch wrap containment force
characterization.
Computer Modelling
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Distillation
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Box edge loading is a function of the pallet stiffness.
Stiffer Pallet lower box stress
Less Stiff Pallet Higher box stress
When does it matter most?
When racked. Especially in a weak direction!
Assuming that the pallet is designed according to best practices:• Gap between deckboards isn’t too high• All box corners are supported by deckboards• Be careful with bottom deckboard layout for
stacked > 1 high
Introducing PDS Unit Load
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Ability to layout and specify common unit loads
LoadSynctm – Can be used by clients to specify unit loads
and provide the design details to PDS pallet professionals
Perform basic corrugated box design calculations
Determine box load factors
Predict unit load displacement
Specify pallet stiffness required to produce a desired box
load factor
Design a pallet to meet desired stiffness and box load factorEvoke a cultural shift that encourages end users to recognize important interactions between the load & pallet and begin specifying pallet stiffness.
Are we there yet?
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Baby Steps
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• PDS limitations• Regular Slotted Containers (RSC)’s• Column stacked – interlock stacked tends to be
better for the pallet and worse for the boxes• Symmetrical layouts in two planes• 80% pallet coverage• No overhang
• Support conditions• Racked across length• Racked across width• Stacked (maybe)
What can you do with it?
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• Gain insight into how boxes and pallets interact and use this to optimize the entire unit load.
• The box on the left sustained damage during a month-long creep test (just sitting there) as the load began to concentrate on the outside edge.
Why does it matter?
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• Packaging failure may still occur even though the pallet is OK.
• This could cause rejection of the unit load or an expensive cleanup.
• Design optimization – only use the needed material where it is required and save what is not necessary.
Design Optimization
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$ $$$$
National Wooden Pallet & Container Association
A tool to help you build a relationship with your clients
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Thank You.