The destruction of unfit banknotes in today’s world is primarily done through the shredding and granulating of the notes so these can be further processed in a safe and sustainable manner. In this article we will discuss the technique behind these two methods.
Why shred and granulate banknotes?
To make sure all banknotes keep their validity, the damaged or unfit notes are disposed of. Several decades ago, there was a switch in the way this was done for paper type cash. Before this switch, governments would allow the disposal of banknotes by means of incineration. This meant that no preprocessing was done and notes were burned. Even though notes have always primarily consisted of paper type materials, the ink and necessary security features made for the release of chemicals in the incineration process. Central Banks then had to come up with ways to more sustainably and of course safely destroy banknotes. This is where shredding and granulating surfaced as a solution.
(Cross-cut) Shredding banknotes
Initially, the banknotes are shredded. In the case of banknote destruction, the shredder consists of slow contra-rotating shafts on which shredder knives are positioned. Reason for this being the potential to shred large volumes at a time. Depending on the material and desired performance and shred size, various shredder knives may be used. Shredders are often used as a first stage destruction step when destroying bundles of 1,000 banknotes. This can be seen in the video below.
Granulating the banknote shreds
After the initial volume reduction, a granulator further reduces the size of the shreds. A granulator is a high-speed rotating knife mill, which is often used in the second stage of destruction within off-line destruction systems. The granulator cutting technology is based on a combination of stator and rotor knives. These blades, made of special steel come with sharpening reserve, allowing re-sharpening of the knives and thus longer life-time.
After the banknotes are shredded, a classifying screen positioned underneath the rotating knives guarantees the pre-defined shred size.
The size of these shreds can vary as we will discuss in our article on shred handling. This way the shreds can be more homogenously processed.
Have you become interested in shredding type solution for banknotes? Or would you like to know more about the process behind our banknote destruction systems?
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