Design and development of a high-efficiency die for compaction of AA7075-based matrix composites for cylindrical roller bearing applications
摘要
The compaction process in powder metallurgy plays a crucial role in distributing the physical and mechanical characteristics along the compaction axis of the compacts. In this study, a newly developed die, proposed as a cost-effective alternative to conventional double-action dies, was designed, modeled, and analyzed using FEM to enhance the compaction efficiency of AA7075 matrix composites. D3 tool steel was used to manufacture the die parts. This die design is intended for fabricating cylindrical roller elements of bearings, which require high strength, excellent tribological characteristics, and low manufacturing costs. Composites of AA7075 with 6% B4C were fabricated using the developed die and thoroughly investigated for their physical, tribological, and mechanical characteristics. The failure mechanism of the AA7075/B4C composites was homogeneous along the sample compared to the composites prepared by the uniaxial die. The microstructure of the composites showed a uniform distribution of B4C particles in the aluminum alloy AA7075 and good interfacial bonding between the reinforcements and matrix. The AA7075/6%B4C composites exhibited a significant increase in compression strength by approximately 25.79% (433.97 MPa), a weight reduction of about 11.07% (2.53 g/cc), and a reduction in wear loss by about 61.14% (0.708 mm³) compared to earlier studies. It was also discovered that the developed die requires about 50% less compaction load than the uniaxial die. Overall, the proposed die design and the resulting AA7075/B₄C composites show strong potential for manufacturing cylindrical roller bearings in sectors such as automotive, defense, and aerospace.