Grain-size effect on the forging formability of mini gears

Demand for micromachine parts, including mini gears, has been increasing recently because of the continuously decreasing size of consumer electronic products. Forging is a conventional method of manufacturing mini gears, and it is characterized by a higher production rate, low material cost, and low total cost. Therefore, many researchers have focused on improving the technology used for forging mini gears. The present study investigated the effect of grain size of a material on the die cavity filling rate for the material during the forging of mini gears. Experimental results were compared against those of a simulation software for analyzing the applicability of software to simulations of materials with different grain sizes. The analysis indicated that materials with large grain sizes exhibit poor material flow capacity on the die base plate compared with materials with smaller grain sizes. For materials with large grain sizes, the maximum load required to fill die cavities is lower. The difference in the maximum load between the experimental results and the simulation results increased when the grain size exceeded the addendum thickness.