Adjustable Sheet Metal Pallet Design
Adjustable Sheet Metal Pallet Design
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Manufacturing Engineering Co-op - Subzero, Inc.
Main Skills Used:
Main Skills Used:
CAD Design (Solidworks)
Design for Prototyping
Human Centered Design
Vendor Selection & Cost Reduction
Project Background
Project Background
In this project I designed pallets to move product between process steps for the cutting, forming and stamping of the stainless steel sheet metal that formed the inside of Cove dishwashers. The pallet needed to accommodate both the standard and short size, while also ensuring easy unloading by operators and relocation with either a pallet jack or forklift.
The sheet metal would undergo three process steps as shown on the left. The product was first drawn, introducing some curvature to the panel, then selected cuts were made. The highlighted steps were the points where this pallet would be used in storing material for the next process.
Design Criteria
Design Criteria
Must store 50 -100 sheets per pallet
Must have non-scratch base
Would like the pallets to stack for storage when unloaded
Must be adjustable between "Short" and "Tall" parts
Must be maneuverable with forklift
Would like to be maneuverable with pallet jack
Cove dishwashers come in two height configurations, short and tall. Note the curvature of the sheet metal panels after processing.
Initial Design
Initial Design
Initially 80/20 Aluminum Extrusion was selected for the material choice for the following reasons:
Low quantity (only 12 needed)
Fasteners allowed for adjustments (if necessary)
Readily sourced and quick turnaround
In-house assembly
Gate set-points (left), and linear rails (below)
This design featured a gate on linear rails with set-points for each configuration, a plastic base that followed the form profile to prevent bowing, and stacking posts for the unloaded storage (shown above).
In developing this design I discovered a few challenges that made me revisit the material selection choice:
This design would use many fasteners. These have a tendency to work loose over time, especially when subjected to vibrations such as loaded travel over a shop floor.
The gate-design with set-points was over-engineered. In seeking feedback from operators and other stakeholders, the linear rails and pin sets were decided to be unnecessary.
The cost of materials was high. After sourcing multiple vendors for the 80/20 extrusion parts, the cost per pallet was estimated to be $3400.
Final Design
Final Design
A steel frame weldment was considered for the next design, to address the concern of the fasteners loosening overtime. This design is much more robust, and retains the stacking posts for storage, while also incorporating wide channels for the forklift prongs. These channels could also be switched to c-channels to facilitate use with a pallet jack. The gate-design was reassessed to simplify the mechanism of switching between "tall" and "short" parts.
Improvements:
Improvements:
Cheaper - $1200 per pallet vs $3400 for the first design
More robust - no fasteners
Simpler to use
Next Steps:
Next Steps:
Unfortunately I had to leave the project to another co-op when I returned to grad school. The last step I completed was creating a functional prototype out of scrap aluminum to answer the remaining question of post-height. The ergonomic zone, pictured on the right, shows the limits for loading and unloading the pallet. These pallets were to be manually loaded from a workbench. I incorporated operator feedback and safety factors to determine the effective height range for loading the pallet, and passed that along to my successor in the project along with these designs.
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