F flute: thickness, flutes per foot and strength
F flute is a micro flute about 1/32 in thick with roughly 125 flutes per foot. It is used where corrugated replaces folding carton, for small printed boxes.
Key numbers
| Construction | Single wall: one medium, two liners |
|---|---|
| Nominal caliper | 0.0313 in · 0.8 mm |
| Flutes per foot | 125 ± 4 (420 per metre) |
| OD minus ID, length and width | 0.063 in |
| OD minus ID, depth | 0.094 in |
| McKee strength vs C flute, same ECT | 45% |
Strength ratio = √(caliper ÷ C-flute caliper), from the McKee formula with ECT and perimeter held equal.
Trade-offs
- Very thin: little stacking strength on its own
- The smoothest corrugated print surface
- Fewer plants run it than E
Typical uses
- Small retail and cosmetic boxes
- Point-of-sale packs
Estimated box compression at 10 sizes
| Inside size, in | 23 ECT | 29 ECT | 44 ECT | 55 ECT |
|---|---|---|---|---|
| 8 × 6 × 4 | 126 | 159 | 242 | 302 |
| 10 × 8 × 6 | 143 | 181 | 274 | 342 |
| 12 × 12 × 12 | 165 | 208 | 316 | 395 |
| 14 × 10 × 8 | 165 | 208 | 316 | 395 |
| 16 × 12 × 10 | 179 | 225 | 342 | 427 |
| 18 × 12 × 12 | 185 | 233 | 354 | 442 |
| 18 × 18 × 18 | 203 | 255 | 387 | 484 |
| 20 × 16 × 14 | 203 | 255 | 387 | 484 |
| 24 × 18 × 18 | 219 | 276 | 418 | 523 |
| 24 × 24 × 24 | 234 | 295 | 447 | 559 |
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.