Analysis and Correction of Defects for Deep Drawing Process of Stainless Sink by Use of Finite Element Simulation

Abstract

Finite Element Method (FEM) becomes one of the most useful techniques to analyze problems in sheet metal forming processes because of this technique can reduce cost and time in die design and trial step [1]. This research was aimed to predict the optimal parameters in order to eliminate cracks and wrinkles on stainless steel sink product under deep drawing named “DLS50”. The material was made from Stainless Steel 304 with thickness 0.6 mm. The parameters that had been investigated were punch angle and velocity as well as pressure of the punch. In order to simplify the process, punch and die in the simulation were assumed to be a rigid body, which neglected the small effect of elastic deformation. The properties of stainless steel sheet was assumed to be anisotropic, behaved according to constitutive equation of power law and deformed elastic-viscoplastic, which followed Barlat 3 components yield function. The deformation for Forming Limit Diagram (FLD) was predicted by the Keeler equation. Most of the defects such as cracks and wrinkles were found during the process on the parts. In the past, practical productions were performed by trial and error, which involved high production cost, long lead time, and wasted materials. From the prediction results, decreasing punch velocity from 50 mm/s to 8.33 mm/s would reduce the blank shearing zone on the corner bottom of the part and remove cracks in the process. The performing of the stainless sink by decreasing pressure in the process from 2.3 bar to 2 bar, and adjusting the punch shape increasing 5 mm. each side would increase formability of sheet metal in all direction, the reduction of cracking tendency zone out of the part. In conclusion by using the simulation technique, the production quality and performance had been improved.