1. What is the McKee Formula?

The McKee formula calculates Box Compression Test (BCT) from Edge Crush Test (ECT) values, taking into account the thickness and perimeter of the corrugated board. It provides a reliable estimation of a box's stacking strength.

2. How Does the Calculator Work?

The calculator uses the McKee formula:

Where:

• \( ECT \) — Edge Crush Test value (lb/in)
• \( Thickness \) — Board thickness (in)
• \( Perimeter \) — Box perimeter (in)
• 5.87 — McKee constant coefficient

Explanation: The formula accounts for the relationship between edge crush strength and overall box compression strength, considering the geometric properties of the box.

3. Importance of BCT Calculation

Details: Accurate BCT estimation is crucial for packaging design, determining appropriate stacking heights, ensuring product safety during transportation and storage, and optimizing packaging costs.

4. Using the Calculator

Tips: Enter ECT in lb/in, thickness in inches, and perimeter in inches. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between ECT and BCT?
A: ECT measures the edgewise compressive strength of corrugated board, while BCT measures the compressive strength of a complete box.

Q2: How accurate is the McKee formula?
A: The McKee formula provides a good estimation but actual BCT can 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, with higher values indicating stronger board.

Q4: When should I use this calculation?
A: Use this calculation during packaging design phase to estimate box strength before physical testing.

Q5: Are there limitations to this formula?
A: The formula works best for regular slotted containers and may be less accurate for specialty box designs or under extreme environmental conditions.