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 and§45m/min for a particular profile. The highest exit§temperature increased from 542°C to 567°C when the§extrusion speed was increased from 25m/min to 45m/min.§Three types of die pick-up were identified. They were§named as normal pick-up, die line pick-up and lump§pick-up. Normal pick-up occurred regardless of the§extrusion speed and exit temperature; however the§amount of normal pick-up did not increase when the§extrusion speed was increased. Die line pick-up §occurred when the extrusion speed was 45m/min and§appeared only on the die lines. Lump pick-up is not§significant 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, Mg2Si§particles react with aluminium and excess silicon to§form liquid. However normal pick-up and die line§pick-up still occurred at temperatures lower and§higher than 555°C and therefore it confirms that§eutectic reactions do not influence formation of pickup.§Therefore die pick-up is most likely to be caused §due to a mechanical process rather§than a metallurgical process.