Why we also used a planetary mixer rather than rapid mixer granulator.
The design and working principles of Planetary Mixer (PLM) and Rapid Mixer cum Granulator (RMG) are different. The RMG has an advantage that both initial mixing of dry powders and granulation can be done in same equipment. However, in the Planetary mixer (PLM) dry mixing of powders before granulation is carried out and granulation is carried out partly. This is because there is a tendancy of lump formation of the wet mass in the PLM. Hence, after first stage of granulation, the granular mass is transferred and passed through sieve or a multimill to get desired size of granules. However, in case of RMG there are high speed “Chopper” blades which break the granular mass (lumps) to get desired size of granules. Hence generally separate sieving may not be required in most of the cases. However, it depends upon type of products and wet granulation methods we use.
In both the cases (PLM & RMG) the process must be validated when manufacturing commercial scale batches. The same technique of granulation (PLM or RMG) used during product developement in R & D must be used for manufacturing commercial batches (Scale up). We can not interchange the equipment to produce the batches of a product. Process optimization and process validation must be carried out as a part of “Technology transfer” from R&D scale to commercial scale.
Selection of manufacturing techniques and type of equipment to be used should be decided by R & D. R & D should decide whether to use PLM or RMG.
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Planetary mixer is low shear mixer and RMG is high shear.
both are used for granulation.RMS produce porous granules due to high speed of imprller and chopper so we use low shear.Operator experties and binder addtion rate prevents lump formation