First of all, we take the production of aquatic feed as an example, according to the expanded material and purpose from the structure of the single-screw extruder and twin-screw extruder.

Generally: 

      Single-screw extruder: it is suitable for dealing with all kinds of raw materials and common livestock and poultry feed.

      Twin-screw extruder: the end product requires good molding and beautiful appearance, uniform degree of maturity and density adjustable with the feed (aquatic material, pet food) and high value-added raw materials (ɑ starch, tissue protein) and so on. It should be noted that the above division is not absolute, for example, we recommend the use of twin-screw production of aquafeed, but at present there are a lot of enterprises using a single-screw production of aquafeed. Many articles have been written about the differences between the two for aquafeed production. In short, twin screws have the following advantages over single screws: 

      -High yield, up to 98% or higher.

      -Good pellet molding and uniform pellet shape. Twin-screw mold pressure is very stable, to ensure that the particle molding is consistent. 

      The unique strong pumping ability of twin-screw ensures that there is no back-spraying and clogging phenomenon. After emphasizing the quality, the material contains high vapor content, single screw in the feeding area is prone to overflow of vapor, back spray, resulting in unstable flow of material blocking the machine, while the twin screw will not happen similar situations. 

      -Can continuously and stably produce all kinds of small granule products. In the production of 2mm and below diameter particles, the single screw working condition is not stable, the output rate will plummet and the shape of the material will deteriorate. 

      -Density control is more stable and reliable. The material melts more fully and evenly in the barrel of the twin-screw machine, which can precisely control the production of floating material, sinking material and slow-sinking products. 

      Wide adaptability to formulas, more adaptable to high-energy formula production. Twin-screw can produce high-energy formulations with fat content of 11-13% (up to 17% according to foreign data), while single-screw generally does not exceed 6-8%. 

     -Easy to operate, stable production process. 

      It is because of the many advantages of twin-screw compared with single-screw for aquafeed production that we suggest giving priority to twin-screw expanders in the production of this kind of products. Of course, the investment and production cost of twin-screw is much higher than that of single-screw, which should be considered according to the actual situation.