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McKee Formula:
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The McKee formula converts ECT (Edge Crush Test) to BCT (Box Compression Test) values for corrugated cardboard. It provides a mathematical relationship between these two important strength measurements used in packaging industry.
The calculator uses the McKee formula:
Where:
Explanation: The formula establishes a relationship between the edgewise compression strength and the overall box compression strength, accounting for material thickness and box dimensions.
Details: Accurate BCT estimation is crucial for packaging design, ensuring boxes can withstand stacking loads during storage and transportation without collapsing.
Tips: Enter ECT in lb/in, Thickness in inches, and Perimeter in inches. All values must be valid positive numbers.
Q1: What is the difference between ECT and BCT?
A: ECT measures the edgewise compression strength of corrugated board, while BCT measures the overall box compression strength when loaded vertically.
Q2: How accurate is the McKee formula?
A: The McKee formula provides a good estimation but actual results may vary based on board quality, manufacturing process, and environmental conditions.
Q3: What are typical ECT values for corrugated board?
A: ECT values typically range from 20-80 lb/in for single wall boards, with higher values for double or triple wall constructions.
Q4: When should actual BCT testing be performed instead of calculation?
A: For critical applications or when precise strength data is required, actual compression testing should be conducted rather than relying on calculations.
Q5: Does the formula work for all box styles?
A: The formula works best for regular slotted containers (RSC). Other box styles may require different calculation methods or testing.