Effect of die machining method on the surface roughness and hardness of the workpeace in the forging process

In metal forming processes, surface roughness and hardness of the die and workpiece are effective parameters in friction, which is caused by the manufacturing process of the die and workpiece. In this research, effect of die manufacturing processes on the surface roughness and hardness of the deformed parts has been investigated. The inserts of the dies are made with six machining methods, and the effect of the machining method, lubrication, and percentage of deformation on the surface roughness and hardness of the part has been investigated by performing the heading operation on a ring-shap part. The results show that the surface texture of the parts is affected by the surface texture of the inserts and the surface roughness of the parts is proportional to the surface roughness of the inserts. The surface roughness of the parts increases significantly by increasing the amount of cold work, and the use of lubricant reduces slightly the surface roughness in turning, vertical milling and electric discharge machined inserts but it does not have considerable effect in the rest of the inserts. In the case of using lubricant, the surface hardness of the parts decreases by about 5% on average. With the increase of cold work from 25% to 50%, the surface hardness of the parts increases by about 25% on average. Forming with the electrical discharge machined insert causes the lowest surface hardness of the parts, and the highest surface hardness of the parts is related to the grinded and polished inserts. The texture of the surface of the parts is affected by the texture of the surface of the inserts and the roughness and hardness of the surface of the parts is affected by the machining method of the inserts