B flute: thickness, flutes per foot and strength
B flute is about 1/8 in thick with roughly 47 flutes per foot. It is flatter and stiffer across the face than C, which suits die-cutting, printing and puncture resistance, but stacks less well at the same ECT.
Key numbers
| Construction | Single wall: one medium, two liners |
|---|---|
| Nominal caliper | 0.125 in · 3.2 mm |
| Flutes per foot | 47 ± 3 (154 per metre) |
| OD minus ID, length and width | 0.25 in |
| OD minus ID, depth | 0.375 in |
| McKee strength vs C flute, same ECT | 89% |
Strength ratio = √(caliper ÷ C-flute caliper), from the McKee formula with ECT and perimeter held equal.
Trade-offs
- Thinner than C, so a lower McKee estimate at the same ECT
- More flutes per foot give better crush and puncture resistance
- A good surface for printing and for die-cut styles
Typical uses
- Die-cut mailers and trays
- Canned and dense goods that carry their own load
- Pads and dividers
Estimated box compression at 10 sizes
| Inside size, in | 23 ECT | 29 ECT | 44 ECT | 55 ECT |
|---|---|---|---|---|
| 8 × 6 × 4 | 253 | 318 | 483 | 604 |
| 10 × 8 × 6 | 286 | 361 | 548 | 685 |
| 12 × 12 × 12 | 331 | 417 | 633 | 791 |
| 14 × 10 × 8 | 331 | 417 | 633 | 791 |
| 16 × 12 × 10 | 357 | 450 | 683 | 854 |
| 18 × 12 × 12 | 370 | 466 | 707 | 884 |
| 18 × 18 × 18 | 405 | 511 | 775 | 969 |
| 20 × 16 × 14 | 405 | 511 | 775 | 969 |
| 24 × 18 × 18 | 437 | 552 | 837 | 1,046 |
| 24 × 24 × 24 | 468 | 590 | 895 | 1,118 |
BCT ≈ 5.87 × ECT × √(caliper × perimeter), perimeter = 2(L + W) of the inside size. An estimate; confirm with ASTM D642. Grades shown are ECT values Packgent computes for this wall type, not a list of what mills sell.
Sources
- Foster, G. (1997). "Boxes, Corrugated." In Brody & Marsh (eds.), The Wiley Encyclopedia of Packaging Technology, 2nd ed. Wiley. ISBN 0-471-06397-5 (table reproduced in Wikipedia, "Corrugated fiberboard")
- Packaging Corporation of America: Profiles with a purpose
Last reviewed . See all sources and how Packgent computes.