Film Blowing Machines

The bag making machine is an important tool in the packaging industry. This machine can make plastic, or paper bags of various sizes, shapes and materials. Bag production has become popular with the concept of automated packaging process, which requires less human labor. If you want to know the specifications and prices of Bag Making Machine, please contact us!

• Maintaining a work environment void of oil or grease.
• Never reaching under or over the machine guards.
• Never wearing anything that dangles, such as necklaces, braces, watches, rings, or loose clothing to prevent limbs from getting trapped or pulled into the machine.
• Never disconnecting or by-passing the guard's safety switches.
• Using only quality materials specified for this blow molding process.
• Never climbing between the tie-bars during hydraulic pump operation.
• Always wearing protective gloves when adjusting manifolds or components on the hot die head.
• Never reaching into the machine's throat during granulator operation.
• Knowing the location of the nearest fire extinguisher.
• Always wearing approved ear protection to block out noise.
• Never using steel tools on the parting line, mold cores, and cavities.
• Knowing the location of the nearest first-aid kit.
• Always wearing safety glasses and steel-toed boots.
• Never standing directly below a mold suspended in the air.
• Regularly examining electrical cords and air hoses.
• Using the proper safety equipment when lifting heavy workpiece material.
• Never operating an extrusion blow molding machine without authorization and appropriate training.

Electrical Maintenance

• Ensure the stability and reliability of the power supply, and that performance parameters meet specified requirements.
• Maintain appropriate temperature and humidity consistently, ensure a good transmission line, and eliminate electrostatic hazards.
• Regularly remove dust from radiators.

Note: In electrical maintenance, it is generally prohibited to tamper with after-sale core components.
Feeding Machine System
Immediately check the filter and inspect the negative pressure feeding system for air leakage.
Extruder System

• Carefully observe pressure instruments and main motor current, and perform real-time checks on the net changer.
• Check the gearbox, screw, and main motor for noise and looseness.
• Monitor the frequency, current, and temperature rise of the frequency converter, and regularly clean motor and frequency converter dust.
• Correct thermocouple measurements and address any discrepancies in actual temperature.
• Calibrate the extruder position, adjusting the grooved wheel to ensure the correct angle and level.

Die Head System

• Use a secondary smoking method during startup to prevent temperature overshooting.
• Prior to startup and shutdown, clean accumulated material with a pure copper scraper, and use paraffin to clean the die to reduce hydrogen fluoride's impact on the film bubble.
• Immediately cover the die head with protective felt after shutdown to prevent mold damage.
• Regularly check temperature and current in each zone, as well as heating plug-ins for the die head, correcting temperature differences.
• Calibrate the die head level and align the center point with reconnection; use a torque wrench to remove the molded screw, applying molybdenum disulfide grease to high-temperature areas of the screw.

Wind Ring Maintenance
Immediately check for debris and dust in the air ring.
Reconnection Device Maintenance
Ensure herringbone folding is pollution-free, hammer reconnection (cooling) roller pressure is suitable, and flattening roller operation is flexible.
Corona Processor Maintenance
Regularly clean the high-voltage transformer, coupling roller, coupling frame, and electric control box; adjust coupling clearances.
Check equipment humidity before starting to avoid coupling frame short circuits, and monitor coupling roller bearing running temperature.
Immediately replace the silicone tube.

Bubble Instability
Bubble Breaks: A bubble break occurs when molten material exiting the die is overstretched, resulting in a break in the bubble structure. This can occur when the melt strength of the extruded material is insufficient for the selected blow-up ratio (BUR). To avoid this problem, resin selection can be modified to incorporate a higher-melt-strength material into the film structure to improve the overall melt strength. An example of this is incorporating low-density polyethylene (LDPE) into a linear low-density polyethylene (LLDPE) film to increase its overall melt strength.
Strain Hardening: Strain hardening occurs when molten polymer is rapidly stretched in the machine direction (MD) and stiffens as a result. This causes fluctuations in internal bubble pressure and bubble width. This issue can be prevented by reducing the drawdown ratio. Another solution is to modify the resin selection to decrease the overall elongational viscosity of the film, allowing the film to stretch more in the MD without experiencing any strain hardening.
Unstable Frost Line: In a stable process, the frost line will remain at a constant height above the die and is controlled by the cooling rate, die throughput, and film-thickness uniformity. When a process becomes unstable, the position of the frost line will become unstable as well. One cause of this instability is a non-uniform temperature profile in the extrudate.
Variations in melt temperature may stem from improper screw design for the selected resin, a worn screw, or a failure in a heater or thermocouple. Melt temperatures should be taken for each stream prior to merging to determine which melt layer is the source of the temperature variation. Once located, the screw can be removed and inspected for polymer degradation and screw abrasion. All heaters and thermocouples should also be checked for functionality.
Another common cause of an unstable frost line is a blockage in the die. A non-uniform die throughput may be due to a buildup of degraded material in the die. To avoid this, the die should be inspected for material buildup periodically and cleaned if necessary.
Bubble Fluttering: Bubble fluttering initiates below the frost line and appears as linear marks on the bubble surface in the transverse direction (TD). This fluttering is caused by high air velocity coming from the air ring. Decreasing blower speeds or adjusting air-ring components to reduce the air flow along the bubble surface will prevent bubble fluttering. However, reducing air flow will subsequently decrease the cooling efficiency of the air ring, which may then cause the frost line to drift away from the die, leading to new problems. To avoid this situation, resin selection can be optimized to reduce the overall melt viscosity of the extrudate and decrease the overall melt temperature.

Gauge Variation
Misaligned Die: A common source of gauge variation is a misaligned die gap. A misaligned die will result in a non-uniform flow distribution of material leaving the die. A common indicator of a misaligned die is an offset gauge profile, like the one shown in Fig. 1b. To correct this, the die gap should be checked for uniformity along the circumference. If misaligned, the die can be recentered using the die-adjustment bolts.
Non-Uniform Air-Ring Cooling: Poor or non-uniform air flow coming from the air ring will result in non-uniform film cooling, which will impact the drawdown ratio of the film. This can result in portions of film being stretched more than others, which may lead to gauge variation. To avoid this issue, the air channels in the air ring should be inspected and cleaned periodically to remove any impurities that may cause air-flow disturbances. The air ring should also be checked to confirm it is properly centered on the die.
Non-Uniform Melt Temperature: Non-uniform melt temperature will result in variable bubble cooling rates and die throughputs. A telling sign of a non-uniform melt temperature is a sinusoidal gauge profile. The formation of this sinusoidal gauge variation is related to the flow of a material having a non-uniform melt temperature through a die, a phenomenon known as port lines. As previously described, variations in melt temperature are likely caused by an improperly designed or worn screw.

Interfacial Instability
Zig-Zag Interfacial Instability: This form of instability occurs when an interface experiences excessive shear stress, resulting in the formation of "zig-zag" distortions along the film surface in the TD direction. An image of this instability is shown in Fig.
There are a few known causes of the zig-zag instability. The first is differences in shear viscosity between the materials creating the interface. If the materials have distinctly different shear viscosities, the individual layers will experience differing shear rates at an applied shear stress, causing the zig-zag deformation to appear. This can be mitigated by selecting materials with similar shear viscosities (if possible) to create the interface.
The second cause is an improper layer ratio. If the layer ratio chosen is such that the interface is too close to the die wall, the excessive shear stress will trigger the deformation. To prevent this, the outer layer thickness can be increased to shift the interface away from the wall and reduce the shear stress applied onto it.
The third cause is an improper die design. When designing a die, it is important to properly optimize fluid channels to create a uniform velocity profile throughout the die. Improper die design may lead to the formation of high-shear points and a non-uniform velocity profile, resulting in this instability.
Wave Interfacial Instability: This form of instability is caused by non-uniform elongational deformation occurring at an interface between two materials, resulting in wave-like patterns forming along the bubble surface as it is extruded from the die. The first is associated with an improper layer ratio. If one of the combining layers of the structure is too thin, it will experience more acceleration at the merge point within the die, resulting in a higher rate of elongational deformation in that layer. Layer ratios should be adjusted to allow for a more uniform velocity profile to form downstream of the merge point.

Gels
Unmelted Resin: Unmelted resin is a common type of gel that is typically observed at high extruder throughputs. They are a result of non-uniform melting caused by low-shear regions located within the extruder. To determine if a gel is unmelted resin, heat the gel above its melting temperature, and then let it cool back down. If the gel does not re-appear after cooling, it was unmelted resin. If unmelted resin is present in the film, the extruder screw should be examined and redesigned to minimize the presence of low-shear zones.
Degraded Materials: Material degradation can occur during extrusion if a polymer is exposed to high levels of energy for an extended period of time. These conditions lead to the formation of highly oxidized or crosslinked materials, which appear as gels in the film. Typically these gels are not present immediately after startup. They appear on the film over time as the degraded polymer accumulates within the process.
Highly oxidized gels appear as brittle black specks and can be identified by their fluorescence under UV light. Figure 5 shows an image of a highly oxidized gel taken under polarized light, and an image of the gel fluorescence under UV light. Crosslinked gels have a dark brown appearance and consist of oxidized material, however the degree of oxidation is too low to cause fluorescence under UV light.