How to adjust the temperature of the blown film machine body and die if it is too high?

In the production of plastic film, the barrel and die temperatures of the film blowing machine are critical factors affecting product quality and production efficiency. Precise temperature control ensures uniform plasticization of resin pellets and stable film formation. Excessive temperature, however, not only causes quality issues such as melt fracture and uneven thickness in the film, but can also shorten equipment lifespan and potentially create safety hazards. Therefore, when encountering excessively high barrel or die temperatures, the ability to quickly identify the cause and implement effective adjustments becomes essential for maintaining smooth production.

(A) Heating System Malfunction
The heating system is the core component of temperature control in film blowing machines. Malfunctions often lead to abnormal temperature increases. Heating elements may degrade or fail over extended use, resulting in unstable power output and inaccurate temperature regulation according to programmed settings, causing continuous temperature rise. Temperature controllers, being critical for feedback and adjustment, may fail to accurately detect actual temperatures or transmit control signals to the heating system. This causes sustained operation of heating units and loss of temperature control.

(B) Cooling System Failure
Cooling systems are responsible for dissipating operational heat and maintaining temperature stability. Blockages in cooling water lines or pump failures impede water circulation, preventing timely heat removal from the barrel and die, significantly reducing cooling effectiveness. The air ring, which directly cools the melt, may suffer from blocked outlets or insufficient airflow adjustment. This compromises melt cooling capacity, leading to rising die and barrel temperatures.

(C) Material and Process Issues
Different plastic materials exhibit distinct melting points and processing characteristics. When processing resins with higher melting points using incompatible temperature settings, elevated temperatures are required to achieve proper melting and plasticization, often exceeding normal operating ranges. Additionally, excessive screw rotation speed intensifies friction between the plastic, screw, and barrel, generating substantial frictional heat that markedly increases barrel temperature.

(D) Equipment Wear and Abnormalities
Extended operation causes gradual enlargement of the clearance between the screw and barrel. Excessive clearance prolongs material residence time, subjecting it to continuous compression and friction that generates surplus heat. Rough surfaces within die flow channels increase melt flow resistance. Frictional heat generated during melt flow consequently elevates die temperature.

(A) Adjustments for Excessive Barrel Temperature

Inspect and repair heating system:
Conduct regular comprehensive checks of heating elements. Promptly replace any aged or damaged components. Calibrate or replace malfunctioning temperature controllers to ensure precise heating power regulation according to actual temperature requirements.

Optimize cooling system:
Perform thorough cleaning of cooling water lines to remove internal blockages and ensure unimpeded flow. Repair or replace faulty water pumps to maintain proper cooling circulation. Simultaneously, inspect air rings to clear outlet obstructions and adjust air volume appropriately based on production needs.

Adjust process parameters:
Study the characteristics of the plastic material being used, including its melting point and rheological properties. Appropriately reduce screw rotation speed to minimize friction-induced heat. Reevaluate and adjust heating temperature settings to match material processing requirements.

Equipment maintenance:
Technicians should regularly inspect screw-barrel clearance. Repair or replace components if excessive clearance is detected. Restore or replace other worn parts to maintain precise equipment tolerances and reduce frictional heat generation.

(B) Adjustments for Excessive Die Temperature

Clean and maintain die head:
Periodically disassemble the die for detailed cleaning of internal flow channels. Remove residual plastic impurities and contaminants to ensure smooth channel surfaces and reduce melt flow resistance. Concurrently, inspect die heating units to guarantee uniform temperature distribution and prevent localized overheating.

Adjust cooling and processing:
Enhance cooling at the die section by increasing air volume or optimizing air ring positioning. Appropriately decrease extrusion speed to allow sufficient melt cooling time at the die, preventing temperature spikes caused by inadequate cooling.

(A) Utilizing Built-in Temperature Control Systems
The temperature controllers integrated with film blowing machines serve as primary tools for real-time monitoring. Operators should closely observe temperature readings across all barrel and die zones, comparing them against preset normal ranges. Prompt adjustments should be implemented upon detecting abnormal fluctuations.

(B) Supplementary Monitoring with Infrared Thermometers
Infrared thermometers enable rapid, non-contact surface temperature measurements of barrel and die components. This facilitates assessment of thermal distribution patterns. By measuring temperatures at multiple points, operators ensure uniform heating and prevent localized overheating.

(C) Observing Production Process and Film Quality
Film formation characteristics provide critical indications of proper temperature control. Operators must meticulously inspect film appearance for issues like bubble instability, uneven thickness, or surface roughness. Restoration of stable production and compliant film quality indirectly confirms successful temperature adjustments.

(D) Systematic Recording and Analysis
Establish comprehensive temperature logs with dedicated personnel for periodic data recording. Analyzing historical temperature data reveals patterns and trends, enabling early detection of potential abnormalities and implementation of preventive measures.

Excessive barrel and die temperature in film blowing machines represents a common production challenge, stemming from multiple factors including heating system malfunctions, cooling system failures, material and process issues, as well as equipment wear. Specific corrective measures must align with identified causes, such as repairing heating components, optimizing cooling performance, adjusting process parameters, and performing equipment maintenance. Following temperature adjustments, multiple monitoring methods should confirm restoration to normal operating conditions, ensuring consistent film quality and production efficiency.

Implementing robust maintenance routines and strictly adhering to scientific process parameters during daily operations constitute critical preventive measures against temperature deviations and ensure stable machine performance.