Granulators can be categorized into various types based on their operating principles and application scenarios. Common rotary granulators force powder through a screen using a rotating drum to form cylindrical granules, making them suitable for small-batch production in the pharmaceutical and food industries. Extrusion granulators utilize a screw to push powder into a die, forming granules under high pressure-a method frequently used for chemical raw materials. Meanwhile, spray granulators atomize liquid feedstocks into tiny droplets that rapidly dry into hollow granules in a stream of hot air; this technology is widely used in the production of instant products such as powdered milk and coffee.
Three key factors must be considered when selecting a granulator: raw material characteristics (such as moisture content and viscosity), granule specifications (such as size and density), and production scale. For instance, high-viscosity powders are well-suited for wet granulation, whereas heat-sensitive materials require a fluidized bed granulator capable of low-temperature drying. Additionally, the level of automation is crucial; modern granulators are typically equipped with PLC control systems that monitor parameters like temperature and pressure in real-time, ensuring consistent granule quality.
