# Pkg Solutions

# Shipping case minimum board strength requirements

**Sizes/Materials**

Below are a series of tables, they may be used - **with
caution** - to calculate a likely pack board strength. In these
tables products are assumed to be subjected to the most challenging shipping
modality - parcel carrier. The following table provides guidelines for
minimum recommended material strength for a range of slotted containers
by dimension and weight. These simplified tables do not take into consideration
perimeter vs. depth ratios and in no way relate to pack strength analysis
such as the McKee Formula. These tables should
only be used as a reality check in the absence of further analysis and
testing, and only apply where **none of the three dimensions exceed 7
times any other.**

**Material choice by size and weight - Imperial Units**

Imperial Units | L+W+D=<30" | L+W+D=30" - 49.9" | L+W+D=50" - 90" |

< 10lbs | 200T SW | 275T SW | 275T DW |

10lbs - 19.9lbs | 250T SW | 275T SW | 275T DW |

20lbs - 29.9lbs | 275T SW | 275T DW | 350T DW |

30lbs - 39.9lbs | 275T DW | 350T DW | 350T DW |

40lbs - 65lbs | 350T DW | 350T DW | 350T DW |

**Material
choice by size and weight - Imperial Units - ECT**

Imperial Units | L+W+D=<30" | L+W+D=30" - 49.9" | L+W+D=50" - 90" |

<10lbs | 32 ECT SW | 44 ECT SW | 48 ECT DW |

10lbs - 19.9lbs | 40 ECT SW | 44 ECT SW | 48 ECT DW |

20lbs - 29.9lbs | 44 ECT SW | 48 ECT DW | 51 ECT DW |

30lbs - 39.9lbs | 48 ECT DW | 51 ECT DW | 51 ECT DW |

40lbs - 65lbs | 51 ECT DW | 51 ECT DW | 51 ECT DW |

**Material
choice by size and weight - Metric Units - ECT**

Metric Units | L+W+D=<.75M | L+W+D=.75M-1.19M | L+W+D=1.2M - 2.3M |

< 4.5kg | 32 ECT SW | 44 ECT SW | 48 ECT DW |

4.5kg - 8.9kg | 32 ECT SW | 44 ECT SW | 48 ECT DW |

9kg - 13.9kg | 44 ECT SW | 48 ECT DW | 51 ECT DW |

14kg - 17.9kg | 48 ECT DW | 51 ECT DW | 51 ECT DW |

18kg - 30kg | 51 ECT DW | 51 ECT DW | 51 ECT DW |

**Material choice by Metric size and weight - Mullen Imperial Units**

Metric Units |
L+W+D=<.75M |
L+W+D=.75M-1.19M |
L+W+D=1.2M - 2.3M |

><4.5kg | >200T SW | >275T SW | >275T DW |

>4.5kg - 8.9kg | >250T SW | >275T SW | >275T DW |

>9kg - 13.9kg | >275T SW | >275T DW | >350T DW |

>14kg - 17.9kg | >275T DW | >350T DW | >350T DW |

>18kg - 30kg | >350T DW | >350T DW | >350T DW |

**Material choice by Metric size and weight - Metric Units ECT**

Metric Units | L+W+D=<.75M | L+W+D=.75M-1.19M | L+W+D=1.2M - 2.3M |

<4.5kg | 5.6 KN/m ECT SW | 7.7 KN/m ECT SW | 8.4 KN/m ECT DW |

4.5kg - 8.9kg | 5.6 KN/m ECT SW | 7.7 KN/m ECT SW | 8.4 KN/m ECT DW |

9kg - 13.9kg | 7.7 KN/m ECT SW | 8.4 KN/m ECT DW | 8.9 KN/m ECT DW |

14kg - 17.9kg | 8.4 KN/m ECT DW | 8.9 KN/m ECT DW | 8.9 KN/m ECT DW |

18kg - 30kg | 8.9 KN/m ECT DW | 8.9 KN/m ECT DW | 8.9 KN/m ECT DW |

**Material choice by Metric size and weight - Metric Units - Mullen**

Metric Units | L+W+D=<.75M | L+W+D=.75M-1.19M | L+W+D=1.2M - 2.3M |

< 4.5kg | 1380 KPa SW | 1900 KPa SW | 1900 KPa DW |

4.5kg - 8.9kg | 1725 KPa SW | 1900 KPa SW | 1900 KPa DW |

9kg - 13.9kg | 1900 KPa SW | 1900 KPa DW | 2415 KPa DW |

14kg - 17.9kg | 1900 KPa DW | 2415 KPa DW | 2415 KPa DW |

18kg - 30kg | 2415 KPa DW | 2415 KPa DW | 2415 KPa DW |

**Compression Strength**
- The BoxComp
program can aid in calculating a required board grade for a unitized load
with a great deal of accuracy. It should be remembered that the program
is calibrated against state of the art corrugating and production machinery,
as found in the better box plants around the world. Such machinery is
not available to all manufacturers, however the customization features
of BoxComp do enable some of the manufacture's deficiencies to be taken
into account. Specifying board grades by the required performance characteristics
is often the safest course of action. Paper qualities and make-up are
also subject to variation by global region. Unitized load shipment, usually
via either palletization or containerization normally means that board
ECT would be the prime performance characteristic of any corrugated case.
However, when using single item or mixed load shipping Burst strength
should be given an equal degree of consideration. It should be noted that
the performance of many die-cut designs are difficult to accurately predict
without empirical data. This means that pack testing and transit trials
are often necessary. See Compresive Forces in
Packaging and BoxComp
Help for further information.

**Safety factor** is the primary variable that we can influence in establishing a relationship
between McKee formula calculations and the various environmental factors
to which a package will be exposed. **A minimum safety factor of
3 is recommended in the absence of testing**.

**Economic Size Ratios** for various styles of slotted container are provided for
general guide to the most economic use of corrugated box material relative
to the cubic volume contained, see HERE. These ratios do not take into consideration
manufacturing efficiencies and user friendliness. The most economic use
of corrugated for an RSC is a box whose depth is the same as the length
and twice the width. Such high ratios of depth may not work well for multipacks
where the products need to be easily unpacked or scanned in the box. They
may, however work well for a mixed case situation. Pallet patterns are
also a consideration in the determination of sizes and ratios.

**Materials**

ECT/Mullen Equivalents are guidelines to assist in selecting
materials in the absence of ECT values. There is not a direct performance
equivalence between ECT and Mullen. **ECT**
values should provide the basis for selection whenever possible when compression
strength is the objective.

**Approximate
Equivalence - ECT/Mullen**

Single Wall ECT (lbs/in) |
Mullen (lbs/in^{2}) |
Double Wall ECT (lbs/in) |

32 | 200 | |

40 | 250 | |

44 | 275 | 48 |

55 | 350 | 51 |

400 | 61 | |

500 | 71 | |

600 | 82 |

**Approximate
Equivalence - ECT/Mullen /Kpa/KN/m**

Single Wall ECT (lbs/in) PLI |
Single Wall ECT (KN/m) |
Mullen (lbs/in^{2}) |
Burst (Kpa) |
Double Wall ECT (lbs/in) PLI |
Double Wall ECT (KN/m) |

32 | 5.604 | 200 | 1379 | ||

40 | 7.005 | 250 | 1724 | ||

44 | 7.705 | 275 | 1896 | 48 | 8.406 |

55 | 9.632 | 350 | 2413 | 51 | 8.932 |

400 | 2758 | 61 | 10.683 | ||

500 | 3447 | 71 | 12.434 | ||

600 | 4137 | 82 | 14.361 |