Collapsible Pallet Design

Rotational molding has been successfully applied to the production of numerous pallet configurations because of it advantages in producing low cost, durable products with inexpensive tooling. A few years ago a company in India wanted to capitalize on these benefits by offering a complete product line of collapsible pallets based on this process and contacted IDS as its design firm. This case study will describe the project, the product line and the challenges encountered throughout the project.

This project was especially ambitious because this modular system was intended to perform all the functions of other collapsible pallets shown in the following pictures.

An abbreviated list of specifications from a very comprehensive document has been provided in this case study in the following images and text. They should provide you with a more insightful appreciation of the challenges we faced throughout this project.

Pallet base was to be offered in three versions

• The pallet required to allow 4-way entry for more than 1000 kg load bearing capacity for fork-lift without buckling or bending under load.
  

• Provisions for direct mounting of casters on all configurations
  

• Four pallet volumes, ranging from 425 liters to 1050 liters were to be offered with different height side panels, proportioned according to Indian trucking standards which had a maximum internal height of 2400mm within the trailer.
  

• Added features such as handles and label holders were to be included for hand lifting and identification.
  

• A version was to be offered with 20% openings in side walls for cold storage applications.
  

• Units were to stack with and without the lid.
  

• An option was to be provided for a drop down door to access parts in stacked pallets.
  

• A drainage port was included to permit complete water removal when pallets stored liquids.
  

• A common dust protection lid with optional tamper proof security features was required for all product configurations.
  

• All these specifications resulted in a system that would enable one to assemble pallets in hundreds of different configurations with interchangeable parts. In addition to this long list of challenging requirements, our most difficult obstacle was the poor tolerance control inherent in rotational molding.
  

One of the most difficult challenges resulting from wide tolerance variation was the latch which would lock panels in their upright position. Numerous concepts were developed before arriving upon a final viable design. The following pictures will provide you with sketches of one concept of dozens of ideas that were explored and the final solution.

The final design was based on a split fiberglass rod that could either be straight or folded as shown in these pictures.

When assembled within the pallet it would lock panels in the upright position or be easily released as shown in the following pictures which are self explanatory.

Other challenges resulting from wide tolerance variation included stacking and add-on skids, which required excessive clearances to assure interchangeability. These are clearly depicted in the following pictures.

The final system proved to successfully satisfy all the objectives set forth at the beginning of the project. Pictures of free standing and collapsed pallets are shown in the following slides.