An Investigation into Deep Drawing Process without Blank Holder

Abstract

The limiting drawing ratio (LDR) of deep drawing process is typically investigated through several factors, e.g. tool geometry, Punch pressure, and blank material.  In this paper, an experimental investigation of limiting drawing ratio (LDR) of deep drawing process without blank holder was presented.  A lubricant type, knurled punch, and ram speed are considered as effective parameters on LDR in this work. The effect of knurled punch on LDR and punch load compared to without knurled punch was discussed. The experiments of deep drawing were conducted at different types of lubricants, e.g. Pure oil, pure graphite and mixed oil with powder graphite with different weight ratio (wt%). The effect of different lubricants on punch load and LDR was discussed. LDR and punch load were investigated at different ram speed (e.g, 2, 6, 9 mm/min). The product characteristics were investigated through tests of thickness variation and surfaces hardness of the drawn cup.  Results reveal that the mix of oil and powder graphite with ratio 25 to 75, OG (25-75), was found the best and recommended lubricant type. This recommended lubricant combined with knurled punch results high LDR equals 2.275. The optimal value of punch speed was found as 9 mm/min. the results of this work have a good effect economically wise in the deep drawing process. The present study adopted the enhancement of  LDR and lowering punch load as an effective parameters that tends to cost reduction through minimization of number of stages and power saving,  as an output results, respectively.