Halogen free screws are mainly used for processing halogen-free materials, which are usually used in fields with high environmental requirements. Due to the processing characteristics of halogen-free materials, special attention should be paid to the following when using halogen-free screws:
1. Material Properties
corrosiveHalogen free materials often contain flame retardants such as phosphorus and nitrogen, which may cause corrosion to screws and barrels.
High temperature sensitivityHalogen free materials are prone to decomposition at high temperatures and require strict control of processing temperature.
high viscosityHalogen free materials typically have high viscosity and require high wear resistance and drive system requirements for screws.
2. Screw design
Specialized screwUse screws specifically designed for halogen-free materials, typically with double alloys or special coatings to improve wear resistance and corrosion resistance.
aspect ratioChoose an appropriate aspect ratio (usually 25:1 or higher) to ensure that the material is fully plasticized and evenly mixed.
Thread designOptimize thread design, enhance mixing and shearing effects, and avoid material retention or decomposition.
3. temperature control
Accurate temperature controlStrictly control the temperature of each heating zone to avoid material decomposition caused by excessive temperature.
cooling systemEnsure the normal operation of the cooling system and prevent overheating of the screws and barrel.
4. Cleaning and Maintenance
Timely cleaningImmediately clean the residual halogen-free materials in the screw and barrel after shutdown to prevent material carbonization or corrosion of the equipment.
Use cleaning materialsRegularly use specialized cleaning materials to clean the screws and barrel to avoid residue accumulation.
Check for wear and tearRegularly inspect the wear of screws and barrels, and promptly repair or replace worn parts.
5. Optimization of processing parameters
screw speedAdjust the screw speed according to the material characteristics to avoid excessive speed causing material decomposition.
Back pressure controlAdjust the back pressure appropriately to ensure uniform plasticization of the material while avoiding excessive shearing.
Feeding speedControl the feeding speed to avoid excessive feeding causing excessive screw load.
6. Corrosion resistance and wear resistance
Material selectionThe screw and barrel should be made of corrosion-resistant and wear-resistant dual alloy materials or special coatings (such as nickel based alloys, tungsten carbide coatings, etc.).
surface treatmentHarden the surface of the screw to improve its wear resistance and corrosion resistance.
7. 防止材料分解
Avoid high temperature retentionEnsure that the material stays in the barrel for a short period of time to prevent decomposition at high temperatures.
Monitor exhaustDuring the processing of halogen-free materials, gas may be generated. It is necessary to ensure that the exhaust system is unobstructed to avoid gas retention.
8. Operator training
Operating SpecificationsTrain operators to master the processing characteristics and operating specifications of halogen-free materials.
safety protectionThe decomposition of halogen-free materials may produce harmful gases, and operators need to wear protective equipment.
9. Equipment selection
Specialized equipmentTry to use extruders specifically designed for halogen-free materials to ensure equipment performance matching.
drive systemEnsure that the drive system has sufficient power to cope with the high viscosity characteristics of halogen-free materials.
10. Regular inspection and maintenance
regular inspectionRegularly inspect key components such as screws, barrels, heating coils, bearings, etc. to ensure the normal operation of the equipment.
Lubrication and maintenanceRegularly lubricate the screw drive end bearing to prevent wear caused by insufficient lubrication.