                                     !        " #  —Electromagnetic forming is one of the sheet metal forming processes in which force is applied by an electromagnetic pulse. In this process, sheet metal is deformed rapidly at high strain rates. In this paper, FE simulation has been applied to study distribution of magnetic field formed by spiral coil and inducted eddy current in a circular sheet . At first, magnitude and components of magnetic field intensity have been calculated and compared with experimental results taken from literature. After verifying of simulation results, the effects of sheet thickness on magnetic force magnitude and distribution have been investigated.  Electromagnetic forming (EMF) is a high velocity sheet metal forming technique that is receiving more attention due to a number of its advantages. The process begins by charging a capacitor bank at a sufficient voltage for a specific operation and then discharging it through a coil. The current pulse passing through the coil generates a transient magnetic field. The magnetic field induces a time varying current in the conductive work piece, which generates a magnetic field that opposes the coil field. The eddy current opposes penetration of the magnetic field into the workpiece and a large magnitude of magnetic repulsive force is created between the coil and the work piece .This force is usually referred to as the “magnetic pressure”. In an EMF process, the material can achieve velocities at the order of 100 m/s in less than 0.1ms. where the formability of some materials such as aluminum could be improved .EMF has been in use since the early 1960’s, but it has been applied as a manufacturing technique used mainly for production of axis symmetric parts such as tubes with limited commercial applications for two decades. During this period, Gourdin [1] studied EM ring expansion and derived some simplified equations that could be used for numerical simulation of EMF .In the early of 1970s, Al-Hassani [2] studied the magnetic field intensity and the magnetic pressure distribution on a flat work piece .Work on both experimental and numerical of EM sheet metal forming using a flat spiral coil was performed by Takatsu et al [3] in 1988 . Fenton and Daehn [4] demonstrated that a 2D finite difference code can predict the EMF process accurately . Magnetic force density is one of the most important parameters in EMF process. Understanding of the magnetic force density distribution is needed for any design of proper coil to obtain the desired deformation of work-piece . In this paper, 3D simulations by FE Software MAXWELL are used to calculate the magnetic force distribution on the work-piece during the electromagnetic forming process. At first, magnetic field distribution was calculated and compared with experimental result of reference [3]. Then effect of sheet's thickness was investigated on total magnetic force and distribution of force density.   The numerical analysis for electromagnetic sheet metal forming has been performed by FE software MAXWELL .For this model the effect of work-piece displacement on magnetic field density has been neglected .Moreover it has been assumed that the inductance can be constant during EMF process. Considering constant inductance during forming operation, the discharge current flowing in the flat spiral coil is approximately described by (1). Applied Mechanics and Materials Vols. 110-116 (2012) pp 3506-3511 Online available since 2011/Oct/24 at www.scientific.net © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.110-116.3506 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 132.239.1.231, University of California, San Diego, La Jolla, USA-14/09/14,18:44:25)