Die Temperature Control of ABA Blown Film Machine

Die Temperature Control of ABA Three-Layer Co-Extrusion Blown Film Machine

ABA three-layer co-extrusion blown film machines integrate inner-layer sealing, middle-layer functionality and outer-layer mechanical strength, and are widely used in food, pharmaceutical and other packaging industries. As a core process parameter, die temperature regulation directly affects film plasticization uniformity, melt joint strength, transparency and mechanical properties, which requires precise adjustment based on the characteristics of the three-layer structure.

1. Basis for Die Temperature Setting Matching Raw Materials and Product Standards

Melting processing temperatures vary greatly among materials. For LLDPE inner and outer layers, the processing temperature ranges from 160°C to 220°C. The core HDPE or barrier materials such as EVOH demand higher melting temperatures: HDPE at 180–240°C, and EVOH kept at 210–240°C to prevent thermal degradation.

Product requirements determine temperature settings: raising die lip temperature slows melt crystallization for high-transparency films; slightly higher temperatures boost crystallinity for rigid films; balanced die temperatures are required for impact-resistant films to avoid reduced melt strength caused by overheating.

2. Multi-Zone Independent Temperature Control System of ABA Die Head

Different from single-layer equipment, ABA dies adopt independent temperature control for separate zones: inner runner, core runner, outer runner, inner die lip, outer die lip and feeding joint. Zones are accurately heated by electric heaters or circulating thermal oil. Thermal oil heating delivers uniform, high-precision temperature, ideal for large ABA dies and barrier core layers to eliminate fusion defects from interlayer temperature deviation.

3. Phased Adjustment Operations

Preheating Before Startup

Heat up stepwise slowly to avoid local overheating. After synchronous heating of all zones, hold temperature for 30–60 minutes to stabilize internal die temperature and prevent turbulent melt flow after startup.

Fine Tuning After Startup

Observe extruded melt at die lips. Uniform transparent cylindrical melt indicates proper temperature. Crystal spots or cold streaks require a 5–10°C incremental rise in the corresponding zone without excessive single-zone heating. Thin melt and violently swaying bubbles call for lower die lip temperature to strengthen melt and stabilize bubbles.

4. Key Adjustment for Three-Layer Fusion Seam

Melt bonding interfaces are highly temperature-sensitive. A temperature gap over 15°C between core and inner/outer layers easily causes delamination and weak bonding. Keep the core runner 5–10°C hotter than inner and outer layers for full core plasticization and robust fusion joints.

5. Coordinated Adjustment with Other Process Parameters

High die temperature: lower extrusion speed for sufficient plasticization; reduce cooling air temperature to accelerate shaping and relieve internal film stress.

Low die temperature: slow down cooling to avoid uneven surface crystallization.

Daily maintenance: inspect offset temperature probes and blocked thermal oil circuits; clean residual melt in runners to guarantee stable temperature control.

Conclusion

ABA die temperature management must accommodate functional differences of three layers. Multi-zone independent regulation, staged preheating and coordinated parameter adjustment enable steady production of high-performance films for diverse packaging applications.