Modern and ancient processes combine

Mokume Gane is a unique process involving sheets of different coloured metal alloys bonded together into a laminated billet before being carved or milled to expose interior layers. The material is then hammered or rolled into a flat sheet, which is used to form jewellery (pictured) or hollow ware. The visual effect is stunning, whether it be with the noble metals of silver and gold, or the industrially popular materials of brass and copper. Early on in the development of friction stir, the process was identified as ideally suited for joining dissimilar materials in a similar fashion. The work undertaken by Sheffield Hallam University and TWI involves a novel method for producing mixed metal multi-coloured layered materials using FSW. Using these multi-coloured layers in the process has given TWI unique insight into how the material flows around the friction stir tool and by so doing has enhanced TWI's FSW tool design capability. After reaching steady-state conditions, the patterns formed via FSW are stable and repeat in a regular manner, although still exhibit a small natural and random variation, making each piece unique. The FSW process is capable of making much larger structures than is achievable via Mokume Gane. In time, this could lead to the production of visually stunning architectural panels, it is suggested.