Tinplate - the champion of the circular economy

Even something that is already very good can still be improved. Tinplate, for example, is a packaging material with a very good environmental balance. It can be recycled almost 100%, an infinite number of times and without any loss of quality. The recycling rate for tinplate from private households was 91.4% in Germany in 2020 - making tinplate one of the recycling leaders and champions of the circular economy. However, engineers at thyssenkrupp Rasselstein are using the Finite Element Analysis (FEA) to further optimize the packaging material.

A sustainable system

Tinplate has been used as a packaging material for over 210 years. Today, it is used for food, beverage and aerosol cans, among other things. It is so popular not only because it is so easy to recycle, but also because it is particularly safe. The thin, cold-rolled sheet with tin or chrome coating allows the product to last for a very long time and protects it safely against light and oxygen. And due to its inherent material properties, it can be recycled again and again in the sense of a closed material cycle.

By the way, the popular can will be even more sustainable if bluemint® Steel is used to produce the tinplate. thyssenkrupp Rasselstein already has tinplate made from CO2-reduced bluemint® Steel in its portfolio. For bluemint® Steel, alternative input materials are used in the steel production process. This reduces above all the use of coal for the reduction process in the blast furnace. The result is a reduction in CO2 emissions.

Digital simulations for real improvements

Thus, one could almost think that there's nothing left to improve in the good old food can or spray can. Dr. Manuel Köhl, Head of application technology at thyssenkrupp Rasselstein, maintains that even a very good product is never fully developed. In tinplate, there is still great potential for optimizing the use of materials. However, even the smallest changes in the basic material have a major impact on processability. In particular, machines and tools have to be adapted to new material properties, as it is not possible to foresee how the packaging steel will behave under changed conditions - such as reduced thickness.

Ioana Weinand, Rasselstein development engineer, explains how a method already used in the automotive industry can solve this problem. The Finite Element Method (FEM) refers to a procedure that significantly accelerates product development and optimization by means of virtual analysis of forming and stability processes. The optimizations can thus be carried out digitally and virtually as a simulation.

The concrete advantage: time and resources can be saved because packaging dummies no longer have to be developed, produced and tried out using the "trial and error" method. This is a significant step forward, since in the past, real sample cans had to be produced by the dozen, sometimes even by the hundred, in order to test the feasibility of new concepts. Tests to determine whether ideas for reducing the material of a package can be implemented can now be completely digitized.    

A look into the future

Dr. Manuel Köhl is certain: "It will soon be impossible to imagine life without the FEM." The fact that its importance is increasing is also due to the versatile application possibilities. Already today, the virtual method can be applied to all can types and components. This also includes aerosol can lids and bottoms as well as cam-type caps or bottle caps. Fabian Knieps, a doctoral student in development at Rasselstein, sees additional opportunities for the industry here: "FEM makes it possible to implement completely new product ideas and therefore promotes innovation in the packaging industry. Manufacturers can be more daring and think up more creative solutions." The finite element method will significantly improve the efficiency of product development in the future and ensure more sustainable packaging solutions.