Title: Numerical and experimental study on the effect of die shape and billet size in the forging process of axi-symmetric parts

Authors: Saber Saffar; Bijan Mollaei-Dariani; Massoud Malaki

Addresses: Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), No. 424, Hafez Ave., P.O. Box 15875-4413, Tehran, Iran ' Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), No. 424, Hafez Ave., P.O. Box 15875-4413, Tehran, Iran ' Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), No. 424, Hafez Ave., P.O. Box 15875-4413, Tehran, Iran

Abstract: Precision forging is defined as a flashless near-net-shape forging process which produces parts with high surface quality and with dimensional accuracy. This technique has become a key method in the field of manufacturing to improve productivity and to challenge in these competitive market conditions. This paper presents the effect of die shape and initial billet size on the parameters of axi-symmetrical precision forging including forging force, stress-strain distribution, material flow pattern, and contact pressure between the die and the billet. The less forging force, the cheaper the equipment needed. More homogeneous strain distribution leads to higher reliability of products as well as smoother mechanical properties. Material flow pattern is a shortcut to predicting final grain order and die wear pattern. Contact pressure directly affects the die wear and life. By controlling these parameters, some factors like die life, mechanical properties of product, and equipment costs could be optimised. Results prove that the appropriate billet diameter (D_b/D_d) can be effective factor on the forging force, lower required materials and material flow. A comparison has been done between numerical and experimental results. A good agreement was achieved between theory and practice. [Received 2 April 2011; Revised 19 August 2011; Accepted 29 March 2012]

Keywords: precision forging; material flow; stress; strain distribution; FEM; finite element method; die shape; billet size; axi-symmetric parts; near-net-shape forging; surface quality; surface roughness; forging force; material flow pattern; contact pressure; die wear.

DOI: 10.1504/IJMR.2013.055243

International Journal of Manufacturing Research, 2013 Vol.8 No.3, pp.262 - 276

Published online: 29 Jan 2014 *

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