ORIGINAL ARTICLE Optimization of the design parameters of modified die in hydro-mechanical deep drawing using LS-DYNA Swadesh Kumar Singh & Amrit Dixit & D. Ravi Kumar Received: 11 January 2007 / Accepted: 3 May 2007 / Published online: 14 June 2007 # Springer-Verlag London Limited 2007 Abstract The use of a modified die enhances the limiting draw ratio compared to that obtainable in a conventional deep drawing operation. Application of these dies, in conventional deep drawing, eliminated the use of blank holder but enhances the tendency of wrinkling in drawn products. In hydro-mechanical deep drawing process, the punch deforms the blank to its final shape by moving against a controlled pressurized fluid. In this paper, a new concept of the application of modified dies in hydro- mechanical deep drawing is presented. The finite element (FE) simulations of a deep-drawing process using modified dies are performed using the 2-D explicit finite element code LS-DYNA, with the aim of optimization of design parameters and the results are compared with the experi- mental values. The initial design steps in the design of modified die in finite element simulation were taken from the concept of Tractrix die. The use of Tractrix die enhances the draw ratio but simultaneously increases the tendency of wrinkling. In this paper the design parameters of modified Tractrix die for hydro-mechanical deep drawing are optimized for the successful drawing of cups. It is also experimentally verified that by using such modified dies in hydro-mechanical deep drawing, deeper cups are drawn without wrinkling. Keywords Modified die . Deep drawing . Hydro-mechanical . Finite element simulation . Tractrix die 1 Introduction In hydro-mechanical deep drawing, the flow of fluid is restricted, and as the punch deforms the sheet material inside the die, the pressure inside the chamber increases, which forces the blank against the punch. Fluid in the chamber is pressurized to a certain extent so that blank comes in contact with the punch and presses the sheet against the punch before actual drawing. This is called "prebulging" of the blank and it affects the quality of cup drawn. A strong radial stretching is caused by this upward bulging, suppresses the wrinkling and even those materials which have poor formability can be drawn successfully [1]. There must be an optimum pressure inside the pressure chamber: if the pressure build up is too large, it will increase bulging (as shown in Fig. 1) and will result in tearing of the blank. Swadesh [2] demonstrated this region of safe pressure limit in which cups are drawn without any wrinkling and tearing. If the build up pressure is too small, then it may not be sufficient enough to make any effect on the drawing process. M. R. Jenson et al. [3] calculated this counter pressure by finite difference approximation and by experiments. In a hydrodynamic deep drawing process there is no oil seal to prevent the flow of hydraulic fluid. Thus a constant counter pressure is maintained throughout the punch travel. As the punch moves in, excess fluid passes through the passage between the blank and the die. Int J Adv Manuf Technol (2008) 38:32–37 DOI 10.1007/s00170-007-1083-z DO01083; No of Pages S. K. Singh (*) Department of Mechanical Engineering, GRIET, Bachupally, Hyderabad 500072, India e-mail: Swadesh_108@yahoo.co.in A. Dixit Department of Basic Sciences, GRIET, Bachupally, Hyderabad 500072, India D. R. Kumar Department of Mechanical Engineering, IIT Delhi, New Delhi 110016, India