Fabrication of miniature helical gears by powder extrusion using gas atomized Zn-22%Al powder
(1. Precision Manufacturing Systems Division, Pusan National University,
30 Jangjeon-Dong, Kumjeong-Gu, Busan 609-735, Korea;
2. Dongnam Regional Division, Korea Institute of Industrial Technology,
1274 Jisa-dong, Gangseo-gu, Busan 618-230, Korea;
3. Department of Mechanical Engineering, DONG-A University,
840 Hadan 2-dong, Saha-gu, Busan 604-714, Korea;
4. Engineering Research Center for Net Shape and Die Manufacturing, Pusan National University,
30 Jangjeon-Dong, Kumjeong-Gu, Busan 609-735, Korea)
30 Jangjeon-Dong, Kumjeong-Gu, Busan 609-735, Korea;
2. Dongnam Regional Division, Korea Institute of Industrial Technology,
1274 Jisa-dong, Gangseo-gu, Busan 618-230, Korea;
3. Department of Mechanical Engineering, DONG-A University,
840 Hadan 2-dong, Saha-gu, Busan 604-714, Korea;
4. Engineering Research Center for Net Shape and Die Manufacturing, Pusan National University,
30 Jangjeon-Dong, Kumjeong-Gu, Busan 609-735, Korea)
Abstract: Powder extrusion, which is based on the superplastic behavior of Zn-22%Al eutectoid alloy, was proposed to reduce the forming load and promises to provide fine microstructures in the manufacture of miniature helical gears. The specifications of the helical gears were as follows: module, 0.3; number of teeth, 12; and helix angle, 15°. Compacted powders were consolidated by sintering and solution heat treatment. The consolidated billets consisted of lamellar and fine-grained microstructures. Extrusion experiments were carried out under the following conditions: temperature, 250 °C; strain rates, 2.36×10-3 s-1 and 1.18×10-1 s-1. The mechanical properties of the extruded helical gears were investigated by measurement of the Vickers hardness and extrusion load, and by scanning electron microscopy.
Key words: helical gear; powder extrusion; gas atomized Zn-22%Al powder; superplasticity