How does the two-stage extruder work?

The two-stage extruder, namely the screw extruder, is based on the pressure and shear force generated by the screw rotation, which can make the material fully plasticized and evenly mixed, forming through the mouth die. Usually, the first mixing extruder runs at high speed to obtain better mixing and higher output. The second extruder of the two-stage extruder series must be a large diameter single screw extruder capable of low-speed operation. Then, let's introduce in detail How does the two-stage extruder work?

Here is the content list:

• Uniform melt

• External heating

• Requirements for polymers

• The shape of the diehead

Uniform melt

The two-stage extruder uses pressure and shearing to transform the solid plastic into a uniform melt, which is then carried to the next process. Melt production involves the process of mixing color masterbatch and other additives, blending resin, and regrinding. The finished melt must be uniform in concentration and temperature. The pressure on the two-stage extruder must be high enough to extrude the viscous polymer. The two-stage extruder performs all the above processes through a barrel with a screw and a spiral channel. The plastic pellets enter the barrel through a hopper at one end of the barrel and then are transmitted to the other end of the barrel through a screw.

External heating

For two-stage extruders, the depth of the thread on the screw decreases with the increase of the distance to the hopper for sufficient pressure. The external heating and the internal heat generated by friction between the plastic and the screw soften and melt the plastic.

Requirements for polymers

The design requirements for two-stage extruders are often different for different polymers and applications. Many of the options are related to the outlet, multiple feed ports, special mixing devices along the screw, melt cooling and heating, or no external heat source (an adiabatic plastic extruder), the relative size of the gap variation between the screw and the barrel, and the number of screws.

The shape of the diehead

The material of the two-stage extruder is uniform. In this section, the material should have sufficient residence time to ensure uniformity of composition and temperature. At the end of the barrel of the two-stage extruder, the melt exits the two-stage extruder through a head designed to be in the desired shape. Head made up of alloy steel inner sleeve and carbon steel jacket, in a forming die head, is the role of head rotation movement of the plastic melt into a parallel straight-line movement, uniform smooth import die set, and give necessary to plastic molding pressure, plastic plasticizing compaction in the barrel, is approved by the flow of porous filter plate along a certain head neck into the head forming die, The mold core and mold sleeve are properly matched to form the annular void with decreasing section so that the plastic melt forms a continuous dense tubular coating layer around the core wire.

The two-stage extruder has been widely used in high-filler masterbatch, carbon black masterbatch, etc. It has the advantages of improving filler ratio and output, improving dispersion effect, and no dust.

Nanjing Haisi Extrusion Equipment Co., Ltd. can customize the appropriate equipment according to customer requirements. Welcome to visit our company to order the two-stage extruder, the whole process for customers to choose the appropriate model, and for customers to install and debug, to ensure that customers normal boot operation production.