Simply put, extrusion is the process of converting wetted powders into granules or extrudates of a controlled shape and size.
Extrusion is used as a manufacturing technique in the agrochemical industry for production of water dispersible granules (WDGs) but is also utilized in a number of other industries where a uniform extrudate or pellet with controlled characteristics are desired including specific pharmaceutical, catalyst, and specialty chemical applications. Spheronization can be utilized post extrusion to generate a rounded form where desired.
Powders often have poor flow characteristics that make them difficult to handle. Examples of issues include trouble with dosing, feeding, conveying, or segregation of mixtures. Having material in a uniform granule form greatly alleviates these issues.
Dust generated through powder handling can be a safety concern and impact process yields. Having material in a granulated form greatly reduces dust. Granules produced in low pressure extrusion also have low friability which reduces potential dust generation and allows for safer and more efficient handling.
Pellets produced using extrusion spheronization have a narrow particle size distribution as compared to other techniques. Control and uniformity are important characteristics when formulating an oral solid dosage form, and the process of extrusion spheronization allows formulators and drug manufacturers to produce pellets with a narrow particle size distribution.
The consistent particle size and shape obtained with extrusion allows for more consistency in the fill weight and therefore better dosing.
Granules formed are highly dispersible in water allowing for more efficient application and use.
Low pressure extrusion is a very repeatable and continuous process that doesn’t rely on significant operator input. This allows for a very consistent and repeatable product as well.
The low pressure extrusion process consists of four main steps:
The first step in the low pressure extrusion process is dry mixing. A homogenous dry mixture is created of the active ingredient (product or technical) and adjuvants normally in a ribbon mixer.
The homogenous wet mass that was prepared in the mixing step is then fed into the low pressure extruder below. The wet mix is transported to the extrusion zone where it is wiped through the die (or screen) to produce well formed cylindrical extrudates of a controlled diameter. The extrudates break off by their own weight and drop into the dryer below.
A homogenous wet mixture is then generated by metering the dry material mixture and a solvent (typically water) in a controlled manner into a wet mixer typically a kneader. The wet mass generated in this process needs to be able to hold its shape under pressure but also have enough gliding properties to enable low pressure extrusion.
LCI has a broad range of pelleting technology supported by a team of process experts and a test center where you can validate your solution. Would your product perform better as a pellet? Speak with an engineer about your process goals to get started on a solution.
