E flute: thickness, flutes per foot and strength
E flute is about 1/16 in thick with roughly 90 flutes per foot. It is thin enough to fold like folding carton yet still corrugated, with a smooth surface for printing.
Key numbers
| Construction | Single wall: one medium, two liners |
|---|---|
| Nominal caliper | 0.0625 in · 1.6 mm |
| Flutes per foot | 90 ± 4 (295 per metre) |
| OD minus ID, length and width | 0.125 in |
| OD minus ID, depth | 0.188 in |
| McKee strength vs C flute, same ECT | 63% |
Strength ratio = √(caliper ÷ C-flute caliper), from the McKee formula with ECT and perimeter held equal.
Trade-offs
- Thin, so stacking strength is low; McKee drops with the square root of caliper
- Many flutes per foot give a flat surface and good crush resistance
- Saves space: more boxes per pallet of flat stock, smaller outside dimensions
Typical uses
- Retail and presentation boxes
- Ecommerce mailers where print matters
- The outer ply of EB double wall
Estimated box compression at 10 sizes
| Inside size, in | 23 ECT | 29 ECT | 44 ECT | 55 ECT |
|---|---|---|---|---|
| 8 × 6 × 4 | 179 | 225 | 342 | 427 |
| 10 × 8 × 6 | 203 | 255 | 387 | 484 |
| 12 × 12 × 12 | 234 | 295 | 447 | 559 |
| 14 × 10 × 8 | 234 | 295 | 447 | 559 |
| 16 × 12 × 10 | 253 | 318 | 483 | 604 |
| 18 × 12 × 12 | 261 | 330 | 500 | 625 |
| 18 × 18 × 18 | 286 | 361 | 548 | 685 |
| 20 × 16 × 14 | 286 | 361 | 548 | 685 |
| 24 × 18 × 18 | 309 | 390 | 592 | 740 |
| 24 × 24 × 24 | 331 | 417 | 633 | 791 |
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.