What should I do if there is a broken film during the blowing process of Dalian plastic film blowing machine

The occurrence of film breakage during the production process of Dalian plastic blown film machines is a common but serious problem that affects production efficiency and product quality.

1、 Analysis of the main causes of membrane rupture

1. Raw material issues

Poor quality of raw materials: Raw materials containing impurities, moisture, or degradation can lead to a decrease in membrane bubble strength

Improper formula ratio: Too many or too few additives, such as a mismatch in the ratio of lubricants and anti-static agents

Insufficient drying of raw materials, especially moisture absorbing materials such as nylon, PET, etc

2. Equipment factors

Mold head problem: uneven mold head temperature, material accumulation or damage at the mold mouth

Cooling system malfunction: improper angle of the air ring, uneven air volume, or high temperature of the cooling water

Traction device issue: uneven pressure on the pinch roller, mismatch between traction speed and extrusion speed

3. Improper process parameters

Unreasonable temperature setting: The temperature in each area is too high or too low

Excessive screw speed: leading to high melt pressure or uneven plasticization

Excessive inflation ratio: exceeding the material's tolerance limit

4. Operational factors

Improper startup operation: Start up too quickly or before the temperature reaches the set value

Human interference: Operators touching membrane bubbles or adjusting parameters too aggressively

2、 System solution for membrane rupture problem

1. Raw material control measures

Strict raw material inspection: Check the raw materials for impurities, clumps, or discoloration before use

Adequate drying treatment: Set appropriate drying temperature and time according to material characteristics

PE/PP material: 80-100 ℃, 2-4 hours

PA/PET material: 120-150 ℃, 4-6 hours

Optimize formula ratio: gradually adjust the dosage of additives and record the effect after each adjustment

2. Equipment inspection and maintenance

Mold maintenance:

Regularly disassemble and clean the mold head to remove carbon deposits and degradation products

Check if there are scratches or damage on the mold mouth, and polish it if necessary

Ensure that the heating ring of the mold head is working properly and the temperature distribution is uniform

Cooling system adjustment:

Check if the air outlets of the air ring are unobstructed and adjust the angle of the air ring (usually 15-45 °)

Measure the cooling air velocity to ensure even distribution (generally 4-10m/s)

Check the water temperature (recommended 10-25 ℃) and flow rate of the water cooling system

Traction device calibration:

Check the parallelism and pressure of the pinch roller (usually 0.2-0.5MPa)

Calibration of the matching relationship between traction speed and extrusion speed

3. Optimization of process parameters

Temperature control:

Segmented temperature setting to avoid sudden temperature changes

Typical temperature settings (using LDPE as an example):

Feeding section: 140-160 ℃

Compression section: 170-190 ℃

Measurement section: 180-200 ℃

Mold head: 190-210 ℃

Screw speed adjustment:

Gradually increase the rotational speed based on the stability of the membrane bubble

Maintain the melt pressure within a reasonable range (usually 10-25MPa)

Inflation ratio control:

Generally, the inflation ratio is controlled between 1.5-4:1

The thick film should be taken as a smaller value, while the thin film can be appropriately increased

4. Operating standards

Standard startup procedure:

Preheat the equipment to the set temperature and keep it warm for 30 minutes

Start the extruder at low speed (10-20rpm)

Observe the formation of membrane bubbles and gradually increase the speed

Adjust other parameters after reaching a stable production state

Monitoring during operation:

Regularly check the shape of the membrane bubbles and the cooling effect

Immediate deceleration treatment upon discovery of minor rupture

Record each parameter adjustment and corresponding effect

3、 Emergency response to special circumstances

1. Sudden large-scale rupture of the membrane

Immediately press the emergency stop button

Check for foreign objects entering the extrusion system

Check if there is local overheating in the heating system

2. Periodic membrane rupture

Check for wear on the screw and barrel

Confirm if the feeding system is uniform

It may be caused by unbalanced rotating components. Check the transmission system

3. Repeated membrane rupture at specific locations

Mark the location of the membrane rupture and check the corresponding mold mouth and air ring at that position

Possible local temperature anomalies or uneven cooling

4、 Preventive maintenance recommendations

Establish a regular maintenance plan:

Weekly: Clean the mold head and check the heating element

Monthly: Calibrate temperature sensor, check screw wear

Quarterly: Conduct a comprehensive inspection of the transmission system and electrical components

Operator training:

Training on equipment structure and working principle

Training on common fault identification and handling

Training on Safety Operating Procedures

Establish a production record system:

Record the parameter settings for each production run

Record abnormal situations and handling measures

Analyze historical data to identify optimization space

Through the above systematic analysis and solutions, most of the film breaking problems of blown film machines can be effectively controlled and prevented. The key is to identify the root cause, take targeted measures, and establish preventive mechanisms to ensure sustained and stable production.