Bct Cardboard Calculator

McKee Formula:

\[ BCT = 5.87 \times ECT \times \sqrt{Thickness \times Perimeter} \]

Box Compression Test (BCT):

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1. What is the McKee Formula?

The McKee formula calculates the Box Compression Test (BCT) value for corrugated cardboard boxes. It estimates the maximum compressive strength a box can withstand before failure, using Edge Crush Test (ECT), thickness, and perimeter measurements.

2. How Does the Calculator Work?

The calculator uses the McKee formula:

\[ BCT = 5.87 \times ECT \times \sqrt{Thickness \times Perimeter} \]

Where:

\( BCT \) — Box Compression Test result (lb)
\( ECT \) — Edge Crush Test value (lb/in)
\( Thickness \) — Corrugated board thickness (in)
\( Perimeter \) — Box perimeter measurement (in)

Explanation: The formula demonstrates the relationship between material properties (ECT and thickness) and box dimensions (perimeter) in determining overall box strength.

3. Importance of BCT Calculation

Details: Accurate BCT estimation is crucial for packaging design, ensuring boxes can withstand stacking pressures during storage and transportation, preventing product damage and reducing 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. The calculator provides the estimated compression strength in pounds.

5. Frequently Asked Questions (FAQ)

Q1: What is ECT and how is it measured?
A: Edge Crush Test measures the compression strength of corrugated board perpendicular to the flutes. It's tested using specialized equipment that applies force until the board collapses.

Q2: How accurate is the McKee formula?
A: The McKee formula provides a good estimation for most standard corrugated boxes, but actual BCT can vary based on manufacturing quality, humidity, and box design factors.

Q3: What are typical BCT values for shipping boxes?
A: Typical BCT values range from 200-2000+ lb depending on box size, board grade, and construction. Most shipping boxes require 250-800 lb BCT for safe stacking.

Q4: Does box shape affect BCT calculation?
A: Yes, the perimeter measurement accounts for box dimensions. Square boxes generally have higher BCT than rectangular boxes of the same perimeter due to better load distribution.

Q5: When should actual compression testing be performed?
A: Actual compression testing is recommended for critical applications, custom designs, or when regulatory compliance requires verified performance data beyond theoretical calculations.