Lang et al. (2004) reported that hydromechanical deep drawing using hydraulic counter pressure has many
advantages compared with the conventional square cup forming technologies. A high drawing ratio (3.44), good
surface finish, and high dimensional accuracy of the formed part and also complicated parts can be formed.
Because high forming forces and complex machines are needed; this process seems to be valid only for thin sheets.
Square cup deep drawing with variable distributed blankholding pressure using finely segmented blankholder
and local adaptive controllers was proposed (Yagami, 2004). In this process, a total of 108 segment blankholding
actuators were employed for controlling the material flow of blank into the die cavity. Thickness strain distribution
showed that the material flow was improved but control of segment blankholder force is very difficult and LDR is
low compared to the conventional method.
Wijayathunga and Webb (2006) reported that Explosive forming is a technique that is generally used for
forming large complex shapes and was adopted for producing square cups. Because the process is complex and the
drawing ratio is low, many experimental works and FE-simulation are still needed to assure the process ability to
obtain regular and uniform square cups of considerable drawing ratio.
Mustafa et al (2007) have prepared a test set for multi-point deep drawing process utilizing the multi-point
forming technology for 3D sheet metal parts. Drawability limits of gradually rectangular shaped container have
been observed using multi-pointed punch with a given tool geometry and a draw velocity. The authors claimed that
the technique of multi-point forming decreases production cost of die, provides flexible usage, and it is convenient
to achieve the most even deformation distribution. However, the setup is complex and pitting defect was observed
due to concentrated load at individual punches during forming process. Such concentrated load strongly causes
localized deformation and limits the drawbalibilty