The challenge
There are over 260 billion beverage cans being produced every year worldwide. The United Kingdom is one of the leading markets with over 8.2 billion (steel and aluminium) cans being produced.
A single production line can make up to 500 million cans every year from coils of aluminium or steel. The main procedure to form the body of the can is done in one continuous punch stroke by a 'Bodymaker' in about one fifth of a second.
The Bodymaker punch is made from an extremely heavy hardmetal alloy, to withstand high forces and conditions which would wear away most metals very quickly. However, the punch weight causes problems of vibration and alignment because of the speed with which it has to move, so in order to keep the can dimensions consistent, they need to be removed regularly for maintenance.
The solution
If the density of the punch could be reduced while maintaining or improving its wear resistance and stiffness, then large savings in energy, raw materials and maintenance time could be made. Working with the manufacturer of the punches, Sandvik, and the beverage can manufacturer (in a programme funded by Innovate UK), we investigated how Bodymaker punches wear and how new materials with lower densities might behave when made into new lighter-weight punches.
The impact
Using state-of-the-art electron microscopy techniques, including Electron Backscatter Diffraction and 3D imaging, we investigated the ways in which different hardmetal alloys wear away. We developed a system to test materials in the same environment that the punches experience, simulating the combination of high-stress sliding contact and impact that is found during can forming.
We monitored the performance of the materials over 100,000 cycles, allowing us to identify which grades of material had better wear resistance. The results will help food packaging manufacturers select materials for their equipment that will reduce maintenance and energy costs, and improve the efficiency of their production lines.