Impact of Process Parameters on the Grinding Limit in High-Shear Wet Milling

Knowledge of the impact of process parameters on the minimum achievable (critical) particle size below which breakage is no longer observed for high-shear rotor–stator wet milling (HSWM) operations is vital to the design and optimization of milling processes of active pharmaceutical ingredients. The grinding limit is a result of a balance between material properties and the energy imparted to particles during the milling processes. In turn, the energy imparted to particles depends on the rotation rate, generator geometry, mill configuration, flow rate, etc. In this communication, a master curve was constructed by normalizing critical particle size curves obtained at different cumulative breakage energies using a shift factor that can be determined with minimal experimentation.