Abstract: To refit a crank-shaft press into P/M automatic press is a common way for some small-scale factories.One of the refitting constructions illustrated in this paper is cam operated coining device, which has been successfully used in a number of P/M factories. However, how to draw the outline of coining cam is an important key to the device designing. By studying the coinig process of the axle bushes and analysing the movement law of the follower, we can get the function fomular of working curve of the cam. Then,The problem to draw the outline of the cam can be readily solved.