Mannesmann piercing of ingots by plugs of different shapes

The purpose of the research reported here was to establish how plug shape influences the size and porosity of hollow shells produced by Mannesmann piercing of an ingot. Ingots were cast from 6060 aluminium alloy and then pierced with a solid plug, a plug with a cavity or a hollow plug. Computer simulation of these processes was carried out using ProCast and QForm software and showed that a hollow plug should produce hollow shells with minimal porosity. However, the results of the experimental piercing revealed that the hollow plug in fact produced hollow shells with higher porosity than that of shells produced using either of the other two plugs. This appears to be consequence of the hollow plug losing stability.