# How to Select a Dalian Plastic Film Blowing Machine to Meet Production Requirements Selecting a Dalian plastic film blowing machine is a systematic project that requires comprehensive evaluation across multiple dimensions, including your own production needs, matching technical parameters, manufacturer strength, and long-term operating costs. From core demand analysis to on-site verification, this guide provides actionable purchasing advice for enterprises: ## I. Clarify Your Core Production Needs: Accurate Positioning Is the Premise Before purchasing, clearly answer three key questions to avoid blind selection: ### 1. Product Type and Specifications - **Film material**: PE (LDPE, HDPE), PP, PVC, etc.? Different materials impose distinct requirements on screw mixing and die head design (HDPE, for example, needs a higher screw compression ratio). - **Film application**: Food packaging film (FDA-compliant, high transparency, low precipitation required), agricultural greenhouse film (anti-aging, uniform thickness), or industrial film (high strength, puncture resistance)? - **Specifications**: Width (1m, 2m, 3m), thickness (5μm–50μm), output (500kg, 1 ton, 2 tons per day)? For instance, producing 1.5m-wide, 10μm-thick LDPE food film requires a matching die diameter and screw output capacity. ### 2. Raw Material Characteristics - **Recycled material usage**: If recycled resin with high impurities is used, select a screw with an L/D ratio ≥ 30:1 (enhanced mixing) and wear-resistant alloy material (such as 38CrMoAlA). - **Virgin resin purity**: For high-purity pellets, a conventional L/D ratio (25:1–28:1) can be chosen to reduce costs. ### 3. Site and Supporting Conditions - **Workshop space**: The film blowing line includes unwinding, main extruder, cooling, haul-off, and winding units, requiring sufficient operating space (e.g., a 3m-wide film machine needs a workshop at least 8m long). - **Power supply**: High-power machines (e.g., 150kW) require 380V three-phase electricity; confirm that the workshop transformer capacity is sufficient. ## II. Core Technical Parameters: Key to Matching Production Needs The performance of a film blowing machine is determined by the following parameters, which must be checked one by one: ### 1. Screw System - **Diameter and L/D ratio**: Larger diameter means higher output (approx. 1 ton/day for φ65 screw, 1.5 tons/day for φ80 screw); higher L/D ratio improves mixing (≥30:1 for recycled material, 25:1–28:1 for virgin material). - **Compression ratio**: 2.5:1–3:1 for LDPE, 3.5:1–4:1 for HDPE, to ensure full melting of raw materials. ### 2. Die Head Design - **Type**: Rotary die head (reduces thickness variation to ≤±5%, suitable for high-end films) vs. fixed die head (lower cost, variation approx. ±10%). - **Die diameter**: Positively correlated with film width (blow-up ratio = film width / (π × die diameter), conventional ratio 2–4). For a 2m-wide film, a φ200mm die head is recommended (blow-up ratio ≈ 3.18). ### 3. Cooling System - **Air ring**: Dual-port air ring (more uniform cooling, ideal for thin films) vs. single-port air ring (lower cost); internal cooling is recommended for thick films to lower bubble temperature and increase speed. ### 4. Control System - **PLC touchscreen control** (precise adjustment of temperature, speed, haul-off tension, easy operation) vs. relay control (low cost but poor stability). A PLC system is recommended for process storage and adjustment. ### 5. Haul-Off and Winding - **Haul-off speed**: Must match screw output (approx. 100m/min for φ65 screw); the winder should feature constant tension control to prevent wrinkling or stretching. ## III. Manufacturer Selection: Advantages and Inspection Points of Dalian Local Enterprises As a hub of plastic machinery in Northeast China, Dalian is home to many professional manufacturers (e.g., Dalian Huahan, Dalian Sanlei, Dalian Rubber & Plastic Machinery). Key considerations include: ### 1. Qualifications and Experience Check for ISO9001 certification, special equipment production licenses, at least 5 years of film blowing machine manufacturing experience, and customer cases matching your needs (e.g., food packaging film equipment). ### 2. After-Sales Service Availability of installation, commissioning, and operator training (critical settings such as temperature and die adjustment); on-site response time (within 24 hours); timely supply of wearing parts (screws, die accessories). ### 3. Customization Capability Ability to provide customized designs for special applications (antibacterial film, biodegradable film) such as additive feeding systems. ## IV. Trial Run Verification: Ensuring Actual Production Meets Expectations A trial run is the most direct verification method regardless of parameters: 1. Test production with your own raw materials: inspect film thickness uniformity (via thickness gauge), transparency (fish eyes), and tensile strength (via tensile tester). 2. Operational stability: continuous running for over 2 hours, checking for abnormal noise, temperature fluctuations, and neat winding. 3. Energy consumption test: record power consumption per ton of film to evaluate long-term operating costs. ## V. Cost and Cost-Effectiveness: Focus on Long-Term Value, Not Just Price - **Initial cost**: Avoid excessively low-priced machines, which may use inferior components (e.g., ordinary steel screws) and lead to high failure rates. - **Long-term cost**: Energy-saving motors (variable-frequency) reduce power use by up to 30%; wear-resistant screws extend service life; high-efficiency cooling systems boost output. - **Policy subsidies**: Some regions offer incentives for eco-friendly film blowing machines (low VOC emissions); consult manufacturers for eligibility. ## Conclusion Selecting a Dalian plastic film blowing machine should follow the logic chain: **demand → parameters → manufacturer → trial run → cost**. First define your product and output requirements, then match core components such as screws, dies, and cooling systems. Choose a reputable local manufacturer, verify performance through trial runs, and evaluate long-term cost-effectiveness. Only in this way can you acquire stable, efficient equipment that truly meets your production needs.