SJ Series Plastic Single Screw Extruder Machine

ISO Standard SJ Series Plastic Single Screw Extruder Machine is main part of the core operations in polymer processing and is also a key component in many other processing operations. The foremost goal of a single screw extrusion process is to build pressure in a polymer melt so that it can be extruded through a die or injected into a mold. Most machines are plasticating: they bring in solids in pellet or powder form and melt them as well as building pressure.

Single screw extruder is composed of driven motor, gear reducer box, screw and barrel, casting aluminum heater, cooling blower, hopper and control cabinet. Single screw extruder working principle is as following : When the screw turns, it moves the resin within the hotbarrel. In this way, it reaches the required temperatures as well as mixes thoroughly to form a melt that is homogenous. The pressure which is built up by the single screw extruders then forces the melt from the extruder. It gets out shaped like a die. The whole system has barrier screw that makes sure that the whole resin does not melt in basic extrusion screw.

The following picture shows a cut-away diagram of a simple single screw machine. This diagram shows the arrangement the different parts of the machine. The two units - screw and barrel - interact together to convey the plastic material, melt the material, and then push it through the die.

The screw is rotated at a predetermined speed with the electric motor drive unit and gearbox. Temperature controllers are connected to heating/cooling elements on the barrel to maintain the temperature at the set-point temperatures.

The capability of the screw and barrel assembly to extrude a given material is based on the characteristics or construction of the barrel and screw, the characteristics of the plastics material, and the circumstances under which the system is operated

Overview of Single screw extruder

As the name suggests, single-screw extruders have only one screw located inside the cylindrical barrel. They are primarily used for extruding granules and pre-prepared compounds. The single-screw extruder is considered a very basic form of extruder that simply melts and forms the material. Together, they are responsible for conveying the solids, melting and pumping the melt through the die. A typical construction of a single-screw extruder is shown . A polymer, as powder or pellet, is continuously fed from the hopper into the extruder barrel. The heated barrel melts the polymer and transports the material through the die. The screw channel exerts the force on the polymer by the rotating screw while the stationary barrel gives a breaking force to the rotating polymer and makes the polymer slip slightly on the screw surface. The polymer keeps on rotating while the screw continues to rub on the barrel surface, at a slightly lower speed than the screw itself. The slippage of the polymer on the screw surface along the screw channel results in an output rate.

• Feeding
• Transition or compression
• Metering or melting

Main Technology Paramter of L/D 36:1 Single Screw Extruder