The Screw Barrel and Its Importance for Granulation


The temperature distribution inside the barrel is impor […]

The temperature distribution inside the barrel is important for the proper granulation of powder mixtures. Typically, the temperatures of the inlet and outlet of the screw barrel are approximately the same. However, the temperatures near the center of the screw barrel can differ from one another. In such a case, the temperature inside the screw barrel should be kept above the melting point of the active ingredient to prevent agglomeration.

The screw barrel is a key component of plastic and rubber machinery. When choosing the right screw barrel for your particular application, you must take into consideration its quality and functionality. A good screw barrel will be manufactured with a durable and efficient mechanism. It should be able to handle different materials, including abrasive materials and plastics.

The screw barrel is also essential for the dry granulation process. The screw design should allow for control of the temperature across the granules. For example, a twin screw extruder has two co-rotating screw barrels. The temperature of the screw barrel will vary depending on its location, with the temperature near the outlet being lower than the central portion of the barrel. In general, temperatures along the length of the barrel are around 50 to 100 degrees Celsius.

The screw configuration, speed, and barrel temperature were all controlled during the dry granulation process. The first configuration did not contain a mixing zone, while the second and third configurations had one mixing element each. All three screw configurations produced significant amounts of granulated particles, but the granules produced by the third configuration had a rubbery texture. In both configurations, 89% of the granules produced were in the desired particle size range.

Dry granulation may also use a lubricant to keep the powder mixture from sticking together during the dry granulation process. The lubricant can be magnesium stearate, zinc stearate, calcium stearate, or sodium stearyl fumarate. Other lubricants include talc and glyceryl behenate.

The polymeric carrier used in the dry granulation process should be polymeric. In addition to polymers, it is also possible to use polymers such as poly(lactic acid) and polycarbonates. These materials are suitable for prolonged and delayed release formulations. Optional components may be added to the powder mixture prior to dry granulation, but these should be in a solid state at the barrel temperature.