Hot extrusion of aluminium-polymer profiles with axially-graded cross-sections

Feeding of a pressurized polymer melt into a hollow aluminium profile during extrusion enables the production of solid hybrid profiles in a single process step. Controlling the process by the pressure or the volumetric-flow-rate of the polymer are compared. Process limits are identified as the minimum polymer pressure to ensure profile filling and the maximum polymer pressure to prevent bursting. Within the derived process window, experiments demonstrate the ability to produce a constant or an axially-graded cross-section, as well as form-fit elements along the length. An analytical approach for predicting the resulting internal diameter of the profile is proposed.