Mechanical behavior analysis on the compression molding process of NdFeB by different molding technology

The discrete element model of the compression molding process was established by the EDEM discrete element software to optimize the process of NdFeB powders compression molding. The effects of the different molding conditions (pressing speed and friction coefficient) on the mechanical characteristics of the green pressing (compression force and pressing internal stress) were analyzed to provide the reference for the optimizing of the molding parameters. The results show that, the position of NdFeB powders is the same as that at the time of powder distraction during the molding process, but the powders near the die-stamping area displace greatly. The stress relaxation phenomenon occurs at the molding of green pressing. It is worthy noticing that the pressing speed has the different effects on the peak force of compression, but eventually it will converge to a similar stable value. The addition of lubricant can improve the internal stress state of the green pressing, reduce the compression force, and decrease the relative density of the green pressing. For the large-scale green pressing, the two-directional pressing should be adopted.