Ningbo Fangli Technology Co., Ltd., as a manufacturer with a complete set of extruder production line equipment for nearly 30 years, our PVC pipe extruder adopts advanced parallel twin screw design, which provides a strong guarantee for PVC. Quality and productivity control is an important link in pipe extrusion production, the main points should be paid attention to in tube extrusion production quality control.
1. Selection of raw materials and formula
SG-5 resin with viscosity of (1.7~1.8) ×10-3Pa•s is suitable for hard pipe production. Usually used as a three-salt base lead stabilizer, its thermal stability is good, and good lubricity of lead, barium soap and used to increase the lubricity. In the processing of hard pipes, it is necessary to consider the internal lubrication to reduce the intermolecular force, so that the melt viscosity decreases for forming, and the external lubrication to prevent the melt and hot metal adhesion, so that the surface of the products is bright. Metal soaps are generally used for internal lubrication, while low melting wax is used for external lubrication. Fillers mainly use calcium carbonate and barium (barite powder), calcium carbonate makes the surface performance of the pipe is good, barium can improve the formability, so that the pipe is easy to finalize, both can reduce costs, but remember that too much will affect the performance of the pipe, pressure pipe and corrosion resistant pipe is best not to add or add less fillers.
2. Key points of process
UPVC tube is molded with SG-5 PVC resin, and added with stabilizer, lubricant, filler, pigment, etc. These raw materials are kneading according to the formula after proper treatment. The PVC pipe extruder of Fanglii adopts twin screw extruder, which can be directly molded with powder.
In addition, two points should be paid attention to when the powder is used to extrude pipe directly without granulation: first, twin-screw extruder is the best choice for the direct extrusion of powder. Because the powder has less one mixing shear plasticization process compared with the granular material, the twin-screw extruder can strengthen the shear plasticization and achieve the expected effect; Second, because the granule is compacted than the powder, the heat and heat conduction is poor, so the processing temperature of the powder is about 10℃ lower than the processing temperature of the corresponding granule.
3. Key points of process condition and control
In the production process, since PVC is a kind of heat sensitive material, which requires strict control of PVC molding temperature. Especially for RPVC, since its processing temperature is very close to the decomposition temperature, often resulting to decomposition due to improper temperature control. Therefore, the extrusion temperature should be determined according to the formula, extruder characteristics, die structure, screw speed, temperature measuring point position, thermometer error, temperature measuring point depth, etc.
The above are three key points should be paid attention to quality control of UPVC pipe production. We hope to provide you with some help. If you have any demand, please call us for detailed inquiry. We will provide you with professional equipment procurement suggestions and technical guidance.