Aluminum is highly recyclable, and the energy required to produce recycled ingots is approximately 3–5% of that required for primary production. However, direct wrought-to-wrought recycling remains limited because impurity removal is traditionally performed during casting. Consequently, direct recycling through plastic working processes has not been sufficiently investigated, and the effectiveness of pseudo-port-hole dies for chip materials and chip-size-dependent properties remains unclear. This study aims to achieve direct horizontal recycling of AA6063 alloy chip waste by hot extrusion using a pseudo-port-hole die that introduces strong shear deformation through material diversion and crimping behavior. Hot extrusion experiments and numerical simulations were conducted using both solid and pseudo-port-hole dies. The effects of chip size on extrusion force, surface quality, and tensile properties were evaluated, and the shear strain distribution introduced by the pseudo-port-hole die was analyzed. The results show that the splitting and bonding mechanism in the pseudo-port-hole die imposes significant shear strain throughout the material. Compared with the solid die, extrusion using the pseudo-port-hole die required approximately 1.5 times higher extrusion force but suppressed surface defects in chip billets. Larger chip sizes reduced surface damage, whereas increasing billet density improved tensile strength. Fracture observations revealed that smaller chips produced internal defects that degraded mechanical performance. These findings demonstrate that pseudo-port-hole die extrusion enables direct recycling of AA6063 chips without casting and clarifies the relationship among chip size, bonding behavior, and mechanical properties, providing a viable processing route for energy-efficient aluminum recycling. The combined experimental and simulation approach confirms that severe shear deformation enhances interfacial bonding between chips and stabilizes product quality along the extrusion length. The study establishes processing guidelines for selecting chip size and compaction density to balance extrusion load and mechanical performance in industrial applications. The approach supports sustainable manufacturing and reduces aluminum processing energy.
Urakawa et al. (Thu,) studied this question.