Analysis of the advantages and disadvantages of halogen-free cylinder

The halogen-free barrel is a specialized equipment component designed for extrusion processing of halogen-free flame retardant materials (such as halogen-free cable materials, low smoke halogen-free polyolefins, etc.). Its core advantage lies in adapting to the special processing needs of halogen-free materials, but it also has certain limitations. From the followingAdvantages, disadvantages, application scenarios, and improvement directionsConduct a systematic analysis across four dimensions.

1、 Core advantages of halogen-free barrel

1. Outstanding corrosion resistance
   • reason: Halogen free flame retardant (alkaline, easily corroding ordinary machine barrels (such as 38CrMoAl nitride steel). The halogen-free barrel adoptsBimetallic materialThe substrate is made of alloy steel, and the surface is sprayed with tungsten carbide or nickel based alloy, which increases the corrosion resistance by 3-5 times.
   • dataA certain enterprise uses ordinary machine barrels to process halogen-free materials, with a lifespan of only 3 months; After switching to a bimetallic halogen-free cylinder, the lifespan has been extended to over 12 months.
2. Significantly enhanced wear resistance
   • principleThe halogen-free material is filled with a large amount of inorganic flame retardants (filling amount can reach 60%~70%), which causes severe wear on the inner wall of the machine barrel. The surface hardness of the halogen-free barrel is ≥ HRC65 (ordinary barrel ≤ HRC60), and the wear resistance is increased by more than twice.
3. Optimization of heat conduction efficiency
   • designThe halogen-free barrel adoptsSegmented heating+cooling water channelStructure to ensure temperature uniformity (temperature difference ≤ ± 3 ℃) and avoid local overheating that may cause the decomposition of halogen-free materials.
   • effectCompared to ordinary barrels, halogen-free barrels can reduce energy consumption by 10% to 15%, while also reducing quality issues such as yellowing and burning.
4. Environmental Protection and Safety
   • Halogen-free propertyAvoid using barrel coatings containing heavy metals such as lead and cadmium, and comply with environmental regulations such as RoHS and REACH.
   • Low smoke and non-toxicNo halogen gas is released during the processing, suitable for fields with high environmental requirements (such as rail transit and new energy vehicles).

2、 Limitations of halogen-free cylinder

1. relatively high cost
   • price comparisonThe price of halogen-free cylinder is about 2-3 times that of ordinary cylinder (bimetallic material has high cost and complex processing technology).
   • maintenance costSurface coating repair requires professional equipment, and the cost of a single repair can reach 30% to 50% of the original price of the machine barrel.
2. Limited processing adaptability
   • Material limitationsOnly applicable to halogen-free flame retardant materials. If processing ordinary non halogen-free materials such as PE and PP, it may cause slipping or poor plasticization due to low friction coefficient.
   • Temperature sensitivityThe processing temperature window for halogen-free materials is narrow (usually 160-180 ℃), and precise temperature control is required to prevent decomposition.
3. High initial running in requirements
   • break-in periodThe new barrel needs to be run in with the screw for 20-50 hours, during which the speed and output need to be controlled, otherwise it may accelerate wear.
   • Difficulty of operationExperienced technicians are needed to adjust process parameters (such as back pressure and speed), otherwise uneven plasticization or production fluctuations may occur.
4. Difficult to repair
   • Coating repairAfter the wear of the surface tungsten carbide coating, professional equipment is required for repair, and ordinary machining cannot restore its performance.
   • Long spare parts cycleThe customization cycle for bimetallic machine barrels is usually 4-8 weeks, which affects production continuity.

3、 Application scenarios of halogen-free cylinder

4、 Improvement direction and suggestions

1. Material Optimization
   • New coatingDevelop corrosion-resistant, wear-resistant, and self-lubricating coatings (such as diamond-like carbon film DLC) to reduce friction coefficient and extend lifespan.
   • composite structureAdopting a three-layer structure of substrate, intermediate transition layer, and surface coating to enhance bonding strength.
2. intelligent upgrade
   • online monitoringInstall temperature, pressure, and vibration sensors to monitor the real-time status of the machine barrel and perform predictive maintenance.
   • Adaptive temperature controlDynamically adjust the heating power through PID algorithm to ensure temperature stability.
3. process optimization
   • Segmented temperature controlDesign multi zone heating based on material flow characteristics (such as independent temperature control in zones 6-8) to reduce thermal stress.
   • Low shear designOptimize the gap between the screw and the barrel (0.1~0.3mm), reduce shear heat, and avoid material decomposition.