Aiming to decrease friction coefficient ( μ ) during the forming of magnesium alloy sheets, nine (9) tools with different hole geometries in their surface (flat, elliptical, and circular) were manufactured from steel Boehler W400 VMR (as known as DIN 1.2343). Tribological investigations were accomplished on a strip drawing machine at 288 °C without lubricants. When compared with a standard tool (surface flat), on average, tools with circular geometries in their surface showed the smallest friction coefficient, while tools with elliptical geometries shown higher. The friction coefficient also was confronted with the ratio between area occupied by holes in the surface of the tool and the total tool surface (i.e., factor f (%)), hole diameter (Ø), and the distance between circle centers (d(c,c)). Principal Component Analysis (PCA) complemented the experimental approach. In summary, both approaches (experimental and theoretical) indicated that the manufactured tool with circular geometries on its surface presented lower friction coefficient values on the forming processes of the magnesium AZ31 sheets.

The research is aimed to investigate Bauschinger effect and strain hardening by the application of drawbead-tester. Generally, the drawbead is used to control the material flow into the die cavity in sheet metal forming process. When the material is flowing into the drawbead, it may cause the development of strain hardening and/or Bauschinger effect. This work consists of two main equipment particularly developed for the experiments. They are drawbead-tester and three-point bending device. The drawbead-tester provides the possibility to integrate the optical in-process strain analysis system. Whereas the sheet metal was being formed in the drawbead, the local strain of the sheet metal was evaluated. At the same time, the drawbead restraining and holding forces were measured. The three point bending device and numerical simulation method are used to investigate the Bauschinger effect. In the experiment, the cyclic bending forces were measured and compared with the result obtained by numerical simulation.