The effect of heating temperature and methods towards the formability of deep drawn square metal cup Abstract. Deep drawing operation is one of the most crucial sheet metal forming processes in industrial applications, but it usually requires expensive multi-step production processes, which is necessary in order to produce complex parts. On top of that, room temperature may cause poor formability or failure due to mechanical properties of the material. The objective of this study is to investigate the effects of heating temperature and the most efficient heating position to perform warm square deep drawing operation without failure. Besides that, this study also aims to compare the thickness distribution of drawn cup's profile obtained from experiment and finite element analysis. A warm formability study of aluminium, mild steel and stainless steel sheet metals are tested by deep drawing experimental methods. The Taguchi approach, which applies L9 orthogonal array, is used to conduct experiments. Different sizes of square blanks are deep drawn at room temperature, 100°C, 150°C and 200°C using three heating techniques, which are heating die only, heating punch only and heating both the die and punch. The results show that warm deep drawing process has more uniform thickness distribution within the square cup profile compared to room temperature condition. Furthermore, maximum thinning condition at the punch corner is noticeably reduced. Lower and upper limit of heating temperature exists, as there is a low and hightemperature failure. Combination of stainless steel with 45 mm blank size, heating temperature of 150°C and die heating technique is optimal in order to obtain uniform thickness distribution in square cup deep drawing process.

Product quality is one of the important aspects in deep drawing practice and the variation in process temperature was claimed to improve the quality. Therefore, in this research, the effect of the heating temperature on the drawability of a circular metal cup has been investigated. Firstly, circular metal cups of aluminium, mild steel and stainless steel were drawn from the blank diameters of 60 mm, 65 mm, and 70 mm. The experiment was conducted at room temperature followed by at 100 °C, 150 °C and 200 °C. The Taguchi method was selected as the design of experiment approach, and L9 (34) array design methodology was adopted in this experimental research. The drawability was measured based on the punching force needed to deform the sheet metal blanks. The deep drawing process was conducted at room, and elevated temperature conditions and the response factor was analysed and compared through the analysis of variance (ANOVA) statistical approach. The results obtained from ANOVA indicate that the blank material has a significant influence on the deep drawing process followed by the blank size, heating temperature and heating technique. The optimal parameter combinations are blank diameter of 60 mm, heating temperature of 200 °C and the die and punch heating technique. Out of the three materials investigated, aluminium has a better drawability compared to mild steel and stainless steel.

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