Classification the differences between parallel twin screw extruders and conical twin screw extruders

According to the rotation direction of the twin screw, the extruder can be divided into two forms: 

Co-rotating extruder and Counter-Rotating. Co-rotating extruder: Refers to the two screws rotating in the same direction when working, while counter rotating extruder: Refers to the two screws rotating in opposite directions when working.

According to the degree of parallelism of the axis of a twin screw, it can be divided into two types: parallel axis and intersecting axis. Parallel axis: it is a twin screw extruder, and intersecting axis: it is a conical twin screw extruder. 

Similarities

1. It has a conveying mechanism that forces plastic forward.

2. Has good mixing plasticization ability and dehydration ability.

3. It also has a basic adaptability to materials and plastic product molding processes.

Differences

1. Diameter: The diameter of parallel twin screws is the same, while the small end diameter of conical twin screws is different from the large end diameter.

2. Concentric distance: the Centre-to-centre distance of the flat twin screw is the same, while the two axes of the conical twin screw show an included angle, and the size of the center distance changes along the axis.

3. Length to diameter ratio: Parallel refers to the ratio of the effective length of the screw to the outer circle of the screw. Conical shape refers to the ratio of the effective length of a screw to the average diameter of the large end and the small end.

Individual advantages

1. Parallel twin screw extruder

Because it is limited by the size of the Centre-to-centre distance between the two screws, there is limited space for the radial bearings, thrust bearings and related transmission gears supporting the two output shafts in the transmission gearbox. The small output torque and poor load resistance are its most significant defects.

However, the plasticity of its aspect ratio is its advantage, and it can be increased or decreased according to differences in molding conditions to meet the requirements of plastic processing technology. At the same time, it can also expand the applicability of parallel twin screws, which is difficult for conical twin screw extruders to achieve.

2. Conical twin screw extruder

The two conical screws are horizontally arranged, and the two axes are installed into the barrel at an included angle. The Centre-to-centre distance of the two axes increases gradually from the small end to the large end, making the two output shafts of the transmission gearbox have a larger Centre-to-centre distance.

The gears and gear shafts in these transmission systems, as well as the radial and thrust bearings that support the gear shafts, all leave a large installation space, allowing for the installation of some larger specifications of radial and thrust bearings, and each transmission shaft has a diameter sufficient to transmit torque. Therefore, large working torque and load bearing capacity are a major feature of conical twin screw extruders, which cannot be compared to parallel twin screw extruders.

Jiangsu Xinrongplas Machinery Co.,Ltd focus on manufacturing various plastic pipe extrusion machine such as PPR pipe extrusion machine, PVC pipe extrusion machine, PE pipe extrusion machine etc, welcome to consult.