What is BCT (Box Compression Test)?
The Box Compression Test (BCT) measures the maximum compressive load a corrugated box can withstand before collapsing. This is crucial for determining stacking strength and shipping safety.
Formula
The McKee formula is the most widely used equation for estimating BCT:
[\text{BCT} = 5.876 \times \text{ECT} \times \sqrt{\text{Perimeter} \times \text{Thickness}}]
Where:
- BCT is the Box Compression Test value (lb or kg)
- ECT is the Edge Crush Test value (lb/in or N/mm)
- Perimeter is the box perimeter (inches or cm)
- Thickness is the board thickness (inches or mm)
Example Calculation
For a box with:
- ECT = 120 lb/in
- Perimeter = 50 inches
- Thickness = 2.5 inches
[\text{BCT} = 5.876 \times 120 \times \sqrt{50 \times 2.5}]
[= 5.876 \times 120 \times \sqrt{125}]
[= 5.876 \times 120 \times 11.18]
[\approx 7883.78 \text{ lb}]
Common Applications
- Packaging Design: Determine optimal box strength for product protection
- Stacking: Calculate safe stacking heights in warehouses
- Shipping: Ensure boxes can withstand transport conditions
- Quality Control: Verify corrugated board meets specifications