Abstract
The application range of sintered machine product can be extended by the diecompacting of lengthwise parts which is one of restrictions in a geometric shape.
In this paper, the dimensional precision of lengthwise SUS-304L sintered compacts was improved by high pressure die compacting. The stainless steel powder isdifficult to compact at high pressure because of adhesion between the powder and the die during ejection. The two-step pressing that we proposed as the high pressure die compacting has made it possible to compact at a pressure of 980 MPa.
The result is a decrease of dimensional change with increasing a compacting pressure. However, there is a definite difference between the dimensional change of the center diameter and that of the end diameter in the longituditinal direc-tion of sintered compact. It is presumed that the lengthwise sintered compact distorts, as a consequence of the uneven dimensional change. Then, the cylindri- city indicated by measurement of roundness was inspected. The cilindricity of the compact at 884MPa is reduced by approximately half, as compared with that of the compact at 490MPa. Thus, the high pressure compacting by this method was found to be effective not only for the increase of the density but also for the improvement of dimensional precision.
