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High material efficiency

An egg is a great example of nature’s excellent packing skills. Although an eggshell is extremely fragile, its unusual dome-shaped end makes it a “tough nut to crack” when you squeeze its ends between the palms of your hands. The eggshell is only about 0.3 mm thick and the ratio of eggshell to total egg weight is around 1:10. Paper sacks are even more efficient packaging solutions because of their natural properties. Depending on the product, the weight ratio of a paper sack to its contents can be up to 1:250.

Thanks to our continuous performance improvements, the material efficiency of paper sacks has been greatly enhanced in recent years:

  • The paper requirement per sack has been reduced by 25% over the past two decades, resulting in considerable reductions in costs and natural resources.
  • The strength of sack kraft paper has been optimised by 45% over the same period. Today, just 100 g of paper can hold up to 25 kg of filling material. Hardly any other packaging product can achieve this level of efficiency.

Besides their material benefits, paper sacks also offer advantages in terms of process and cost efficiency:

  • High-porosity paper enables rapid, problem-free venting during filling, without the need for complex and costly air extraction systems. The porosity of sack kraft paper has risen by almost 30% in the last two decades.
  • This makes it possible to achieve filling speeds of up to 6,000 sacks per hour, compared with 2,000 sacks per hour for non-paper sacks.

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The most efficient packaging solution

The natural properties of paper sacks offer considerable efficiency advantages, resulting in lower total costs, as well as smoother and quicker processes when compared to alternative sack packaging. Stina Blombäck, Senior Adviser at CEPI Eurokraft and EUROSAC, explains.

Stina, what makes paper sacks so efficient?

Stina Blombäck: Among the most important reasons is the natural characteristic of sack kraft paper – the porosity. Acting as a filter material, it enables the air used in the filling process for dry bulk goods to escape very quickly. This allows filling speeds that are three times higher than those of non-paper sacks which are not porous. At present, paper sacks are the most efficient packaging solution with regard to filling capacity. Also in terms of machinery investments, paper sacks are a cost-effective choice.

Why is that?

Stina Blombäck: One paper sack filling machine produces the same amount of filled sacks as three non-paper filling machines. Moreover, the machinery needed to fill non-paper sacks is much more complex than for paper sacks: extra systems are needed to extract the air that cannot escape through the material during the filling process. In fact, the investment required is four to five times higher than for paper sack filling machines as a result. Thanks to the uncomplicated construction of a paper sack filling machine, the machine set-up when changing sacks is quick.

What about the later stages in the supply chain?

Stina Blombäck: Porosity also has efficiency benefits during transport and storage. As the air escapes easily from paper packaging, palletisation is typically easier and more efficient than for non-paper sacks. This results in lower heights for the same tonnage, making it possible to achieve greater loads on containers and trucks.

Stina Blombäck
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