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China bag making machine supplier will analyze the most common faults in the production process of plastic shopping bag making machines, and provide practical diagnostic methods and solutions to reduce downtime and improve product qualification rate.
To address common issues in plastic shopping bag making machines regarding core systems, control precision, mechanical and electrical systems, and auxiliary peripherals, the Bag Making Machine Supplier will explain the corresponding solutions one by one.
This is the most critical and error-prone step in the plastic shopping bag making machine’s bag-making process.
Symptoms: Bag edges tear easily, poor sealing leading to air leakage, air bubbles, or burn-through at the seal.
Causes:
● Temperature Issues: Sealing temperature too low (resulting in insufficient fusion) or too high (resulting in charred and brittle plastic).
● Pressure Issues: Insufficient or uneven sealing pressure.
● Time Issues: Sealing time too short, incomplete fusion of the heat-sealed layer.
● Component Contamination: Carbon deposits, dust, or residual plastic on the sealing strip (heat sealer) surface.
Solutions:
● Recalibrate the sealing temperature according to the material and thickness of the plastic film (e.g., PE film is generally recommended to be tested and adjusted within the range of 150-200℃).
● Adjust the spring pressure or cylinder pressure to ensure uniform pressure.
● Regularly clean the sealing blade with a high-temperature cloth (Teflon cloth) or use a special cleaning agent to remove residue.
Symptoms: The bag cut has rough edges, sticking, or fails to cut completely, resulting in the bag sticking together, or the cut is off-center.
Causes:
● Blade Wear: The cutter becomes dull after prolonged use.
● Incorrect Blade Alignment: The engagement depth or gap between the upper and lower blades (or the moving and stationary blades) is improper.
● Insufficient Pressure: Insufficient pneumatic or mechanical pressure results in incomplete cutting.
Solutions:
● Establish a plan for regular blade sharpening or replacement.
● Readjust the cutter gap to ensure even contact along the entire blade length.
● Check the pneumatic system pressure or the mechanical linkage structure to increase cutting force.
Below are solutions for inaccurate positioning and film misalignment in the production of plastic shopping bags using plastic shopping bag making machines.
Symptom: Misaligned printed pattern on the bag, or inconsistent bag length.
Causes:
● Decreased sensitivity of the photoelectric sensor (photocell) or dust accumulation.
● Unstable film tension, causing variations in the spacing between the printed cursors.
● Slippage in the mechanical transmission or wear on the timing belt.
Solutions:
● Clean the photoelectric sensor and recalibrate its sensitivity.
● Check and adjust the unwinding and rewinding tension control system to ensure constant tension.
● Check the feed rollers for wear or insufficient pressure; replace if necessary.
Symptom: The film slides to one side during operation, resulting in uneven bag edges.
Causes:
● Non-parallel guide rollers or dirt adhering to their surfaces.
● Uneven tension in the unwinding frame or inadequate inflation and locking of the air shaft.
● Uneven end faces of the raw film roll.
Solutions:
● Recalibrate the parallelism of the guide rollers using a level.
● Clean all guide roller surfaces, ensuring no adhesive residue remains.
● Install or calibrate the web guiding system (EPC).
Besides the problems with the plastic bags produced, the plastic shopping bag manufacturing machine itself may also issue warnings. Below are the symptoms, causes, and corresponding solutions.
Symptom: Abnormal noise and machine vibration during operation.
Causes:
● Worn or insufficient bearing lubrication.
● Excessive clearance or damage to transmission gears.
● Loose or worn timing belt.
Solutions:
● Stop the machine for inspection, add lubricating oil, or replace worn bearings.
● Adjust gear meshing clearance and replace damaged parts.
Symptom: The main motor does not turn, or the motor casing is abnormally hot to the touch.
Causes:
● Phase loss in power supply, thermal relay overload tripping.
● Short circuit in the motor’s internal coil or stuck bearing.
● Incorrect inverter parameter settings.
Solutions:
● Check the power supply line and three-phase voltage balance.
● Reset the thermal relay and check for mechanical jamming causing overload.
● Clean the motor’s cooling ducts to ensure good heat dissipation.
In addition to the three most common types of malfunctions in plastic shopping bag making machines mentioned above, the following issues also need to be addressed.
Symptom: The finished bag is loose and misaligned at both ends after winding, causing difficulties in subsequent packaging.
Cause Analysis: Improper winding tension setting; sluggish swing arm movement.
Solution: Adjust the tapered curve of the winding tension; check the pressure of the winding pressure rollers.
Symptom: Excessive film adhesion or excessive slippage leads to poor feeding or sealing slippage.
Solution: Replace with raw materials that meet process standards; or adjust the workshop temperature and humidity to improve the film’s coefficient of friction.
Emphasizing the principle of “prevention is better than cure,” reducing the frequency of malfunctions.
1. Daily/Weekly/Monthly Maintenance Checklist:
Daily Inspection: Clean sealing blades and sensors of dust; check oil levels.
Weekly Inspection: Check the tightness of all screws; inspect belts for breakage.
Monthly Inspection: Replace worn blades; add bearing grease.
2. Operating Procedure Recommendations:
Record detailed malfunction phenomena and troubleshooting processes; establish equipment files.
Emphasize operator training: Do not arbitrarily modify core parameters; report malfunctions according to procedures.
While problems with Plastic Shopping Bag Making Machines are varied, troubleshooting step-by-step by following the logical path of “mechanical-electrical-process-materials” can always lead to the root cause. When encountering complex problems, promptly contact the equipment manufacturer or a professional repair team to prevent small issues from escalating into major malfunctions.
If you encounter any difficult technical problems during production, or require professional equipment maintenance and upgrade services, please feel free to contact Chovyting Machinery.
We have an experienced and responsive professional technical team dedicated to providing comprehensive after-sales support and solutions to ensure your equipment is always in optimal operating condition, safeguarding your stable production.
If you have any questions or need help,
feel free to contact with our team.
