Abstract:
This thesis focuses on the study of tool wear in hot closed-die forging. The forging dies were madeof SKD61 steel, JIS material standard, which was hardened to a hardness of 56 HRC. Theworkpiece material was S45C. The forging temperature was 11000C-12000C and the forging speedwas 0.486 m/s. No lubricant was employed during the forging processes. In this work, 2000 partswere forged and the wear behavior (wear distance and worn surface) was studies. The result showsthat there is wear along the edge of the surface in area where flash flow is expected and in the areainside. It was found that the wear distance measured from the upper die is higher than that of thelower die. The worn surface of the upper die was also investigated. It could be observed thatabrasive wear is evident in the area where high material flow takes place. In the middle region of thecavity of the upper die, fatigue wear is found. This is expected to be cause by both mechanical andthermal loading. It was also found that in the area where high stress is developed, severe plasticdeformation is observed which is believed to be the cause of the surface failure in such area. Thedimensions of the forged products were also investigated. It was found that the width of theproducts increases as the die wears gets more severe as expected. Moreover, tool life was alsopredicted by developing the equation expressing the relationship between the wear distance and thenumber of forging cycle. For the process studied in this work, the equation was found to be linearwhich are the predicted tool life to be approximately 5000 cycles.