SmCo5 sintered magnets are produced according the following main processing: milling until single crystal particle size, compaction and sintering. It is necessary high density to maximize remanence, but small grain size to maximize coercivity. A sintering model able to incorporate both, the densification rate and the grain growth rate, is described. This makes easier to find the better sintering conditions for optimization of the magnetic properties (coercivity and remanence). The presented model represents a refinement of previous sintering models, because it takes into account the coupled effects of grain size evolution and shrinkage.