1. Screw diameter (d)
A is related to the required fuel injection quantity: fuel injection quantity = 1/4*π*D2*S (fuel injection stroke) *0.85,
B Generally speaking, the screw diameter d is inversely proportional to the maximum injection pressure and directly proportional to the plasticizing capacity.
2. Conveying part
A. Be responsible for the transportation, pushing and preheating of plastics to ensure that they are preheated to the melting point.
B. Crystalline plastics are longer (such as POM). PA), followed by amorphous materials (such as PS. PU.ABS) and has the shortest thermal sensitivity (such as PVC).
3. Compression part
A. Be responsible for mixing, compressing and pressurizing the plastics. The raw materials passing through this section have almost been completely melted, but they may be mixed unevenly.
B. In this area, the plastic gradually melts, and the volume of the spiral groove must be reduced accordingly to correspond to the reduction of the geometric volume of the plastic. Otherwise, the material pressure is false, the heat transfer is slow, and the exhaust is poor.
C generally accounts for more than 25% of the working length of the screw. However, the compression section of nylon (crystalline material) screw accounts for about 65,438+05% of the working length of the screw. The plastic screw with high viscosity, fire resistance, low conductivity and high additives accounts for 40%\50% of the working length of the screw. PVC screw can account for 65,438+000% of the working length of the screw, and does not generate strong shear heat.
4. Measurement part
A. It generally accounts for 20\25% of the working length of the screw. Ensure that all plastics are melted and evenly mixed.
B. the mixing effect is good when the measuring length is long. If it is too long, the melt will easily stay for too long, resulting in thermal decomposition. If it is too short, the temperature will be uneven.
C don't stay for too long for heat-sensitive plastics such as C.PVC to avoid thermal decomposition. You can use a short metering section or no metering section.
5. Depth of feed spiral groove. Measure the depth of spiral groove
A. The deeper the feeding spiral groove, the greater the conveying capacity, but the spiral strength should be considered. The shallower the metering spiral groove, the higher the plasticizing heat. The higher the mixing performance index. However, the shallower the metering spiral groove, the higher the shear heat. Self-generated heat increases. Excessive temperature rise leads to discoloration or combustion of plastics, which is especially unfavorable for heat-sensitive plastics.
B. the depth of the metering spiral groove =KD=(0.03\0.07)*D.D increase. Then choose a small value for k.
Screw can be said to be the heart of injection molding machine. The quality of the screw determines the quality of the product. The editor synthesized a large number of supplier products. Based on years of experience, he recommended HC's quality products and suppliers.