Guide


GUIDE

- order of the dimensions

 

When specifying the dimensions of packaging we use a specific order.
ALWAYS dimensions are given in order of length x width x height. First, give the dimensions of the package i.e. the length and width, at the end give its height. This is very important because the packaging of the same cubic capacity may have a completely different price by a different configuration of the same dimensions.

 

For example, the packaging:
700x200x600 - to 1.49 m2 of cardboard
700x600x200 - to 2.17 m2 of cardboard

- weight ( grammage), ECT, strength of cardboard

 

Due to the significant differences in technology between manufacturers of cardboard , weight parameters are used less and less frequently
as an indicator of the strength of cardboard. A more reliable indicator is the ECT( Edge Crush Test ), durability for vertical crushing , given in kN. Cardboard with the same weight can have very different ECT,
for example, 5- layer cardboard with factories using the older technology with the weight of 590 g / m2 will be ECT at 5.2 kN - 6.0 kN depending on the used paper components, while the same board with a weight of 590 g / m2 with a modern line will be the parameter of 7.2 kN.

- selection of suitable raw materials, BCT, strength of packaging

 

To complete packages we can use a whole range of different materials, different structure, composition and quality.
Selection of the appropriate raw material will be of crucial importance for the strength and the price of the package.
When selecting the raw material, you can help yourself by calculating the so-called BCT – durability for pressing.

This is particularly useful when we know that it will be stacked in the package. Following the calculation of the theoretical BCT ( Box Compression Test ) can determine the scope of the load that the packaging should bear. Please note that the theoretical calculation presupposes not damaged packaging, even pressure over the entire surface of the package. The formula does not take into account the height of the package. Please also note that the board is very hygroscopic and the strength of the packaging is very influenced by the humidity of the room in which containers are stored. Desiccated packages break, while too moist lose their rigidity.

 

The BCT parameter is calculated according to the formula –

(5.87 * square root (circumference of the package base * thickness of cardboard)
* ECT)

 

BCT - box resistance ( in kg)
The circumference of the package base - (2*length + 2 * width) (given in mm)
The thickness of cardboard ( given in mm ) - B - 3mm, C - 4mm, BE - 4.5-5 mm, BC - about 6.5-7 mm
ECT - board strength in kN / m
Safety factor - number in the range of 3-5 subjectively dependent on storage conditions

 

So for example. 300x200x100 packaging made of cardboard B- flute with a strength of 3.80 kN / m calculated as below
BCT = 5.87 * square root of ((2 * 300 * 200 + 2) * 3) * 3.8 = 1221.75 N
Countable per kg - 1221.75 N / 9.80655 kg / N = 124.59 kg

 

The result is divided by a safety factor (3-5) and get the range - 24.92 - 41.33 kg

 

If the package weight is 5kg for example, we know that the packaging of these parameters stands for sure
stacking in 6 layers to the top, and in favorable conditions even in 9

 

Types and classification of corrugated board



Paperboard is divided by the color, number of layers and the type of the flute.

 

Because of the color cardboard is divided into raw material in natural color, unilaterally - bleached and both sides bleached.
Due to the number of layers paperboard is divided into 2,3,4,5,7 panels.
Due to the type of flute - the most frequent waves B, C, E, and combinations thereof - BC, BE. They differ in the amount and density of flute.

 

2-layer ( single face ) paperboard occure mainly in the form wound roll. Well suited for securing products that have irregular shapes. It can be used as a replacement for bubble wrap. Also good for securing furniture boards.

 

3-layer ( single wall ) cardboard in B, C, E - flute and different weights. This is the basic type of cardboard that works out in packaging production of medium and small size. Looking at the cross section of 3-ply paperboard you can see a layer of paper, a flute, and a further layer of paper.

 

4-layer (single face double wall ) cardboard, a cardboard with visible on the outside flute, works in the production of decorative packaging, eg. for wine.

 

5-layer ( double wall ) cardboard, the raw material used for larger boxes, or if you need more
package strength. Looking at the cross we see a layer of paper, a flute, another layer of paper, another flute, and another layer of paper.

 

7-layer ( triple wall ) cardboard is used for large-size packaging requiring very high strength.

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