Selection principle of screw


Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with nearly 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.


Screw is the main part of extrusion system. The change of the geometry of its parts directly affects the working performance of the screw. It has a very significant impact on the output and quality of plastic products.


Here, we briefly introduce the selection principle of the screw as follows


1. According to the types of plastic products: there are many types of plastic, including crystalline and non crystalline. When they are extruded to produce products, they have different requirements for temperature conditions and their viscosity, stability and fluidity. Therefore, when producing different kinds of plastic products, we should choose different types of screws.

2. The influence of the resistance of the die of the head on the structural dimension of the screw. The depth of the screw groove in the homogenizing section of the screw thread should be matched with the resistance of the head. If the resistance of the head is large, this section of the screw groove should be shallower; On the contrary, when the resistance is small, the screw groove should be deeper. For the exhaust type extruder, the depth of the screw groove in the homogenization section of the second stage is required to be deeper than that of the homogenization section of the first section of screw, otherwise, the discharge port is prone to overflow.

3. Selection according to the use of the extruder: the extruder with different uses can select the screw according to the working property and the variety of extruded plastic. If it is only used for the selection of one plastic product, you can order a special screw extruder according to the requirements of the plastic product. If the extruder wants to extrude a variety of products of different materials, the screw should be selected to have greater versatility.


We hope that the above information can provide you with some help. If you need more information, Ningbo Fangli Technology Co., Ltd. welcomes you to contact for a detailed inquiry, we will provide you with professional technical guidance or equipment procurement suggestions.

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