What should be noted when operating a three-layer co extrusion blown film machine?

The three-layer co extrusion blown film machine is a widely used equipment in plastic film production, which can simultaneously extrude three layers of different materials of plastic to form a film with composite properties. Due to its complex structure and high operational requirements, it is necessary to pay attention to multiple aspects during the operation process to ensure the normal operation of the equipment, stable product quality, and the safety of the operators.

1、 Equipment preparation

material preparation

Before operation, it is necessary to ensure that the raw materials required for the three-layer co extrusion blown film machine (such as PE, PP, EVA, etc.) are fully prepared and meet production requirements. Plastic particles of different materials should be stored separately to avoid mixing. Raw materials need to undergo drying treatment, especially for materials with strong moisture absorption properties (such as PA, PET, etc.), to prevent the occurrence of bubbles or poor film surface during the production process.

Equipment inspection

Before starting up, a comprehensive inspection of the equipment should be conducted, including the extruder, die head, air ring, traction device, winding device, and other components. Ensure that all components are not loose, damaged, or blocked by foreign objects. Check if the heating system, cooling system, and air pressure system are functioning properly to ensure that the equipment is in good condition.

Temperature setting

Reasonably set the temperature of each area of the extruder according to the production materials and product requirements. Usually, the temperature of the extruder gradually increases from the feed section to the die head to ensure that the plastic is fully melted. The control of die temperature is particularly important. Excessive temperature may lead to unstable film bubbles, while low temperature may result in poor extrusion or rough film surface.

2、 Operation process

Power on preheating

Before formal production, the equipment needs to be preheated, usually for 30 minutes to 1 hour, to ensure that the temperature in each heating zone reaches the set value. During the preheating process, it is necessary to observe whether the temperature display is normal to avoid local overheating or insufficient temperature.

Start the extruder

After preheating is completed, gradually start the extruder and run it from low speed to observe the extrusion situation. Ensure that the plastic melt is evenly extruded without obvious bubbles or impurities. The extrusion speed should be gradually adjusted according to production requirements to avoid unstable film bubbles caused by excessive speed.

Membrane bubble forming

After the melt is extruded from the die, film bubbles are blown out through the air ring. The air volume and pressure of the wind ring need to be adjusted according to the size and thickness of the membrane bubble to ensure the stability and uniformity of the membrane bubble. The cooling rate of the film bubble can also affect the performance of the film, and it needs to be controlled reasonably according to the material characteristics.

Traction and winding

After passing through the traction device, the membrane bubble enters the winding device for winding. The traction speed should match the extrusion speed to avoid excessive or insufficient stretching of the film. The winding tension needs to be adjusted according to the thickness and material of the film to ensure that the winding is neat and wrinkle free.

Quality monitoring

During the production process, it is necessary to monitor the thickness, width, transparency, surface smoothness, and other indicators of the film in real-time. By using online detection equipment or manual sampling, timely detection and adjustment of production parameters can be made to ensure that product quality meets requirements.

3、 Maintenance and upkeep

regular cleaning

After production is completed, the equipment needs to be thoroughly cleaned, especially in areas such as mold heads and air rings that are prone to residue accumulation. The residual plastic melt can affect the quality of the next production and may even cause equipment damage.

lubricating maintenance

Regularly lubricate the moving parts of the equipment (such as screws, bearings, chains, etc.) to reduce wear and extend the service life of the equipment. The selection of lubricating oil should meet the equipment requirements and avoid using inappropriate lubricating oil that may cause component damage.

Inspect vulnerable parts

Some components of the three-layer co extrusion blown film machine, such as screws, sealing rings, heaters, etc., are vulnerable parts and need to be inspected and replaced regularly. Timely replacement of damaged components can prevent equipment failures and ensure production continuity.

4、 Safety precautions

Operator training

The personnel operating the three-layer co extrusion blown film machine need to undergo professional training, be familiar with the structure, operation process, and common troubleshooting methods of the equipment. Untrained personnel are not allowed to operate equipment without authorization.

Protective measures

When the equipment is running, operators need to wear necessary protective equipment, such as gloves, goggles, etc., to prevent injury caused by high-temperature melt or mechanical components. Safety warning signs should be set up around the equipment to prevent unrelated personnel from approaching.

EMERGENCY STOP

If any abnormal situations occur during the operation of the equipment (such as poor extrusion, membrane bubble rupture, abnormal equipment noise, etc.), the operator should immediately press the emergency stop button to stop the equipment operation and promptly investigate the cause of the malfunction.

Electrical safety

The three-layer co extrusion blown film machine involves a large number of electrical equipment, and operators need to pay attention to electrical safety to avoid electric shock accidents. Regularly inspect electrical circuits and wiring terminals to ensure no looseness or aging.

5、 Common problems and solutions

Unstable membrane bubble

Possible reasons include uneven airflow in the air ring, excessive extrusion speed, and improper temperature control. This can be solved by adjusting the air volume of the air ring, reducing the extrusion speed, or resetting the temperature.

Uneven film thickness

Possible reasons include uneven clearance between the mold heads, unstable traction speed, and poor quality of raw materials. This can be solved by adjusting the gap between the mold heads, stabilizing the traction speed, or replacing the raw materials.

Bubbles or impurities appear on the membrane surface

Possible reasons include insufficient drying of raw materials, foreign objects inside the extruder, and incomplete cleaning of the die head. This can be solved by strengthening the drying of raw materials and cleaning the extruder or die.

The operation of a three-layer co extrusion blown film machine requires operators to have a high level of technical proficiency and a sense of responsibility. Every step from equipment preparation to production process must be strictly carried out in accordance with operating procedures to ensure the normal operation of equipment and stable product quality. At the same time, regular maintenance and safety measures are also key to ensuring the long-term stable operation of the equipment. Through scientific operation and management, production efficiency can be effectively improved, production costs can be reduced, and greater economic benefits can be created for enterprises.