Effects of Extrusion Process Conditions on "Die Pick-Up"

In this research AA6060 alloy was used and was extruded at 25m/min, 30m/min, 35m/min, 40m/min and45m/min for a particular profile. The highest exittemperature increased from 542°C to 567°C when theextrusion speed was increased from 25m/min to 45m/min.Three types of die pick-up were identified. They werenamed as normal pick-up, die line pick-up and lumppick-up. Normal pick-up occurred regardless of theextrusion speed and exit temperature; however theamount of normal pick-up did not increase when theextrusion speed was increased. Die line pick-up occurred when the extrusion speed was 45m/min andappeared only on the die lines. Lump pick-up is notsignificant since it was very rare.AA6060 (0.4%Mg and 0.5%Si) alloy has about 0.27% excess silicon and therefore at 555°C, Mg2Siparticles react with aluminium and excess silicon toform liquid. However normal pick-up and die linepick-up still occurred at temperatures lower andhigher than 555°C and therefore it confirms thateutectic reactions do not influence formation of pickup.Therefore die pick-up is most likely to be caused due to a mechanical process ratherthan a metallurgical process.

Robbie Peris was brought up in Sri Lanka and migrated to New Zealand in 2002. He obtained his BE(Hons) and ME(Hons) fromAUT University Auckland New Zealand. He did his Masters Thesiswith Fletcher Aluminium. Currently Robbie Peris is working as aResearch Officer at AUT University and is part of the metalforming group.