A Sustainable Direct Recycling of Aluminum Chip (AA6061) in Hot Press Forging Employing Response Surface Methodology

The present study is aimed at investigating a new approach of direct recycling using the hot press forging process. In the study, the chip sizes of AA6061 that produced from high speed milling were used and the mechanical property of the recycled chip of AA 6061 was studied. Response surface methodology (RSM) was used as the appropriate approach for the experimental design and optimization of the response investigated. Central composite design (CCD) based on face centred cubic design was applied in designing the experiments to evaluate the effects of three main operating variables. Three main operating variables investigated i.e. chip size, pre-compaction, and holding time was used to determine the mechanical properties by measuring the ultimate tensile strength (UTS)as the response variable. The results of mechanical property of the recycled chips were compared with the original AA6061 aluminium billet. Result of mechanical properties shows holding time has the most influential effect followed by pre-compaction, and chip size has the least effect on UTS. Hot pressed AA6061 aluminium alloy at holding time 120 minutes, 4 times pre-compaction cycle, and large chip size shows the best UTS with reasonablePred R2 of 0.8866 and 98% suggested solution for desirability. Therefore, it can be concluded that, hot press forging could be one of the alternative metal waste recycling processes instead of conventional method that has been carried out without melting phase which contributes to a sustainable manufacturing process technology in the future.