An Investigation of Magnesium Stearate Mixing Performance in a V-Blender Through Passive Vibration Measurements

Prior to compression in tablet manufacturing, a lubricant is added and mixed in a V-blender to ensure the mixture is ejected from the tablet die smoothly. Mixing is conducted batch-wise and must be analyzed offline afterwards to ensure the mixture is uniform and will produce desired tablet properties, thereby a costly and time-consuming step within the manufacturing process. To improve process efficiency, inline monitoring methods using passive acoustic emissions or vibration measurements could be implemented. Methods are non-destructive, non-invasive, and have a reduced capital cost compared to traditional methods. Using an accelerometer affixed to the lid of the V-shell, magnesium stearate was added to glass beads and monitored to determine the effect of loading configuration and fill level on mixing performance and measured vibrations. Axial loading configurations performed better than radial configurations due to the limited axial dispersion from the geometry of the V-shell. Mixing was hindered at an increased fill level due to convective and axial dispersion. The optimal fill level of a V-blender was found to be 21-23% by volume. Monitoring magnesium stearate mixing using passive vibration measurements is a non-intrusive and potentially inline method that could significantly improve pharmaceutical process efficiency.