www.tjprc.org editor@tjprc.org EFFECT OF BLANK HOLDER FORCE AND COUNTERFORCE ON WORKPIECE QUALITY IN SHEET METAL EXTRUSION PROCESS BY FINITE ELEMENT METHOD KORAKOD PANGLILAD 1 & BOPIT BUBPHACHOT 2 * 1 Engineering, Division of Building and Grounds, Office of the President, Mahasarakham University, Maha Sarakham, Thailand 2 Associate Professor, Heat-Pipe and Thermal Tools Design Research Unit (HTDR), Department of Mechanical Engineering, Faculty of Engineering, Mahasarakham University, Maha Sarakham, Thailand ABSTRACT This research is a study of the effect of blank holder force and counterforce on workpiece quality in the sheet metal extrusion process by finite element computer simulation. The workpieces in finite element simulation were medium carbon steel (AISI: 1045) with a thickness of 10 mm. The simulation model requires that a punch diameter of 12.7 mm, a die diameter of 5 mm, different blank holder force and counterforce with the changing material properties were compared at the depth of 1, 2, 3 and 4 mm respectively. From the results, it was found that the increased blank holder force and counterforce affect a small increase in effective stress and effective strain in workpieces. The results of the study show the influence of the blank holder force and counterforce affected the quality of workpiece in the sheet metal compression process. KEYWORDS: Blank holder force; Counterforce; Sheet Metal Extrusion Process & Finite Element Method Received: Nov 02, 2020; Accepted: Nov 22, 2020; Published: Dec 22, 2020; Paper Id.: IJMPERDDEC202021 1. INTRODUCTION The sheet metal press process is the most important process in the automotive parts manufacturing industry. In order to produce a quality product, it is necessary to study the parameters for use as a basis for machining molds which can study various variables by machining molds and then doing a real production experiment. In this case, there is used a high budget for studying, but there is another way to save money and time to experiment. This method is a computer simulation. The computer simulation is being developed and becoming more and more popular. Since the computer has developed to assist in the mathematical processing by finite element method which makes it convenient to analyzed engineering problems. The finite element computer simulation is a very useful method for product design, planning production processes, helps in selecting suitable variables in the mold design and determining the optimal forming process. In addition, it can also be used to analyze production problems to determine the fault cause. This method will reduce the number of trial and error and save time and cost for the experiment. Therefore, researchers have studied and submitted research articles that confirm the accuracy of the actual process experiments compared with the process simulation using the finite element method. In 2010, Suriyapha et al [1] studies the effect of die radius on the sheet metal extrusion in the fine blanking process (SME- FB) surface which investigated the formation of the failure defection with respect to the several die radiuses by using the Finite Element Method (FEM). From the results, it indicated that applying the small die radius caused the Original Article International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN(P): 2249–6890; ISSN(E): 2249–8001 Vol. 10, Issue 6, Dec2020, 187-194 © TJPRC Pvt. Ltd.