The pin type screw is named for setting one or several sets of mixing pins near the end of the melting section to the metering section. The plastic particles produced when the solid bed collapses tend to mix with the melt, have less chance of getting heat, are less prone to melting, and even do not melt completely when they reach the end of the screw. If a pin is placed in this area, it will inevitably cause the flow to agitate and thereby produce local high shear to enhance the melting of the solid particles. In addition, the set pins will also contribute to the increase in internal pressure, thereby also ensuring that the grooves are filled and compacted.
The placement and arrangement of the pins, as well as the size and number, affect the mixing of the materials. The setting position is generally 20% to 30% of the unmelted solid material in the axial direction of the screw (close to the end of the compression section). The arrangement is generally such that the rows of pins are perpendicular to the groove, and the groove is surrounded by a circle or a circle. In order to enhance the mixing effect, the pin is also densely packed within 3D from the end of the metering section. The size and number of pins generally depends on the diameter of the screw.
The disadvantage of the pin screw is that it reduces the yield per screw of the screw by 5% to 15%, while also increasing the melt temperature accordingly. In order to counteract this effect, the depth of the metering section groove should be appropriately designed during design.
Since the design of the pin type screw is relatively simple, and the pin is mounted on the screw is easy, even in a plastics processing factory, the application is wide.
Contact us: 0086-15958098091, available in WhatsApp, Wechat, Imo, Messenger.