Selection method when replacing screw barrel Usually th […]
Selection method when replacing screw barrel
Usually the screw can be divided into ordinary type, gradual type, mutation type, mixing type, separation type, split type and various barrier type, pin type, DIS split type and exhaust type, etc.; the number of screw heads can be single Or become first class.
For plastics without flame retardants, they can be processed using ordinary general-purpose screws, and only need to select different diameters according to different melt viscosities. If it is plastic with special properties, special products or plastic with special particle shape, special screw must be used. For a certain kind of plastic, the general purpose screw is not as superior as the special screw in terms of plasticization and power consumption. The following is an introduction to various special products and special screws manufactured for special needs.
The screw has a relatively large compression and adopts imported high-alloy steel fully hardened treatment, which can effectively withstand high torque and high pressure impact. The surface is plated with hard chromium to reduce surface adhesion and degradation. The plasticization effect is good, the color mixing is good, and the low shear design has low heat generation. The degradation rate is low. Generally, the middle diameter is used to form PMMA, PP-R, PC, resistive ABS, etc. when adding toner, the effect is good.
CP, CA acid screw components:
In view of the strong corrosive characteristics of acidic plastics such as CP and CA, the screw, melt barrel and other plasticized parts are specially designed in structure and surface treatment.
The screw assembly has good corrosion resistance. It is recommended to use a dual alloy barrel for corrosion resistance.
PVC special screw
PVC plastics can be divided into granular and powdery forms, which are very sensitive to temperature and easy to decompose, with high viscosity and strong corrosiveness. The design of the screw has two characteristics: the surface must
It must be chrome-plated; there is no rubber ring and glue meson.
The screw has good plasticization, low shear heating, and acid corrosion resistance. Because there is no rubber ring, it cannot be used for low-viscosity plastics and products with precise injection speed and pressure classification.
There are two types of screw designs: screw and dispensing head integrated; screw and dispensing head separated. For products with high quality requirements and only single plastic (PVC), the conjoined type is most suitable. Otherwise, the split type can be used. However, it should be noted that the separation of the screw and the glue head may cause material accumulation. But what kind of screw to choose, our company recommends that you must add a special thermometer for precise temperature control. Because of the need for heat dissipation and cooling, when making PVC products, the melt cylinder should be used with forced air cooling and the screw. Except soft PVC for making toys.
PPO special screw
PPO is an amorphous material, difficult to melt, easy to block, sensitive to shear, and easy to degrade.
It is recommended to use double alloys to improve wear resistance and corrosion resistance. Grade C is sufficient. The screw feeds smoothly and produces stable pressure.
PBT+GF special screw
PBT is a saturated resin, semi-crystalline material, with high melting degree, rapid crystal solidification, easy decomposition, sensitive to pressure, and glass fiber needs to be added.
Double alloys must be used to improve wear resistance. According to the amount of weaving, there are three engineering grades of C, B, and A to choose from, and the pressure produced by the screw is stable. It has a good effect on molding PBT+GF, PA+GF and other crystalline low viscosity ordinary engineering plastics.
Marble special screw
Two options: A: Only need to replace the marble effect screw; B: Replace the whole set of marble screw barrel, control the computer to modify the program or add an electrical plug-in.
Bakelite, urea special screw feed tube group
The material pipe is heated by hot oil loop type, and the screw is recommended to be C-grade double alloy; the old plastic machine can also be modified into bakelite injection.
Mixing head enhances the color mixing effect
The mixing head is another design of the glue head, which mainly enhances the color mixing effect, but has the following limitations: it will cause the back pressure to increase when melting the glue; the melting time will increase; it is not suitable for high viscosity plastics, such as PMMA, PC etc. If the customer is not satisfied with the color mixing, the back pressure of the melt can be increased and the screw speed can be reduced, which will have a certain effect. If customers do not want to use the mixing head to add color mixing effect, they can also use chrysanthemum injection meson.
(Stainless steel) Conjoined chat tube head, extended nozzle, slingshot nozzle and other plastic injection screws