What are the debugging techniques for PE blown film machine

1、 Preparation work before debugging PE blown film machine

Equipment inspection

Before starting up, it is necessary to conduct a comprehensive inspection of all components of the equipment to ensure that they are in good condition, including key parts such as screws, molds, air rings, and traction devices

Confirm that the power supply voltage is stable and all electrical connections are firm and not loose

Check if the cooling system and air path system are unobstructed and there are no leaks

Raw material preparation

Select suitable PE raw materials (LDPE, LLDPE, HDPE or mixtures) according to production requirements

The raw materials need to be fully dried, and it is generally recommended to dry them at 60-80 ℃ for 2-4 hours

Check whether there are impurities mixed in the raw materials and filter them if necessary

Temperature setting

Set the temperature of each zone according to the characteristics of the raw materials, and the temperature generally increases in a gradient from the feed inlet to the mold head

Typical temperature range for LDPE: 160-220 ℃

Typical temperature range for LLDPE: 180-230 ℃

Typical temperature range for HDPE: 190-250 ℃

2、 Startup debugging steps

Preheating stage

First, turn on the heating system and slowly raise the temperature to the set point

After reaching the set temperature, it is necessary to keep it warm for 30-60 minutes to ensure uniform and stable temperature

Check that the actual temperature at each temperature control point does not deviate from the set value by more than ± 5 ℃

Low speed start

Start the engine at a lower speed and observe if the current changes normally

The initial discharge may be uneven, gradually increase the speed after the material flow stabilizes

Check the discharge condition of the mold head, which should be in a uniform "noodle like" shape

Membrane guiding operation

After the melt flows out uniformly from the mold head, the film pulling operation begins

First, use your hands or auxiliary tools to pull the membrane bubble upwards

After the membrane bubble stabilizes, slowly introduce compressed air to form stable bubbles

3、 Key parameter debugging skills

temperature control

Excessive melt temperature can cause unstable film bubbles and easily lead to the phenomenon of "shark skin"

If the temperature is too low, the fluidity of the melt will be poor and the glossiness of the film surface will decrease

The temperature can be determined by observing the surface of the membrane bubble: smoothness and transparency are preferred

Wind ring regulation

The size of the air circulation directly affects the cooling effect and membrane bubble stability

Generally set the air volume to 60-80% and the air pressure to 0.3-0.6MPa

The position of the wind ring should be about 50-100mm away from the mold head, and can be adjusted according to the shape of the film bubble

traction speed

The traction speed and extrusion speed need to be matched to avoid excessive stretching or accumulation of film bubbles

The traction ratio (traction speed/extrusion speed) is generally controlled between 2:1 and 4:1

The traction speed can be adjusted by measuring the film thickness distribution

Bubble stability control

The ratio of bubble diameter to height should be maintained between 1:3 and 1:5

Bubble shaking may be caused by uneven temperature or insufficient cooling

It can be improved by adjusting the air volume of the air ring, traction speed, or die gap

4、 Common problems and solutions

Unstable membrane bubble

Reason: Uneven temperature, improper placement of air ring, high humidity of raw materials

Solution: Check the temperature curve, adjust the position of the air ring, and extend the drying time of the raw materials

There are crystal dots on the membrane surface

Reason: Raw material degradation, damaged filter screen, high screw speed

Solution: Replace raw materials or filter screens, reduce screw speed, clean mold heads

Uneven thickness

Reason: Uneven gap between mold heads, uneven cooling of air rings, and uneven pressure of traction rollers

Solution: Adjust the mold head bolts, check the uniformity of the air ring outlet, calibrate the traction roller

Wrinkles on the membrane surface

Reason: Insufficient cooling, uneven winding tension, unstable film bubbles

Solution: Strengthen cooling, adjust winding tension, and stabilize film bubbles

5、 Optimization and debugging skills

Process parameter record

Establish a complete debugging record table, recording the parameters and effects of each adjustment

Including key parameters such as temperature, speed, air volume, traction speed, etc

Provide reference basis for subsequent production

Mold maintenance

Regularly disassemble and clean the mold head to prevent material accumulation and carbonization

Check if there is any damage to the lip mold and repair it in a timely manner

When assembling the mold head, it is necessary to evenly tighten the bolts to avoid deformation

Screw maintenance

Before stopping the machine, it is necessary to thoroughly clean the screw with cleaning material

Regularly check the wear of the screw

Avoid prolonged low-temperature operation to prevent screw damage

Electrical system inspection

Regularly check the working status of heating coils and thermocouples

Calibrate the temperature control system to ensure accurate display

Check if the operating current of each motor is normal

6、 Safety precautions

high-temperature protection

During the debugging process, the temperature of the mold head, screw and other parts is very high, so avoid direct contact

Wear heat-resistant gloves and other protective equipment during operation

Electrical safety

Check if the equipment is properly grounded

Avoid operating electrical equipment in humid environments

Mechanical safety

Internal maintenance is not allowed during equipment operation

Protective covers should be installed for moving parts such as traction rollers and winding devices

emergency response

Familiar with the location of the emergency stop button

Prepare fire extinguishing equipment to deal with possible melting material fires

By using the debugging methods and techniques of the above system, the production efficiency and product quality of the PE blown film machine can be improved. During the debugging process, it is necessary to be patient and meticulous, adjust parameters flexibly according to the actual situation, gradually accumulate experience, and ultimately achieve a better production state.