Common Problems of the Pouch Packing Machine

As a core packaging device in industries such as food, pharmaceuticals, and chemicals, the stability of pouch packing machines directly impacts production efficiency and product quality. Despite the advantages of high automation and convenient operation in modern models, various issues may still arise during long-term operation. This article, combining equipment principles with production practices, systematically reviews common problems and proposes targeted solutions for pouch packing machines.​

I. Defects in Sealing Quality​

1. Inadequate Sealing or Air Leakage​

Main Causes:​

• Improper heat-sealing temperature (too low fails to fully melt the material, while too high causes carbonization).​

• Insufficient or uneven heat-sealing pressure (unstable air cylinder pressure, deformed heat-sealing molds).​

• Too short heat-sealing time (parameters not adjusted synchronously during high-speed operation).​

• Moisture in packaging materials or insufficient interlayer peel strength of composite films.​

Solutions:​

• Calibrate the heat-sealing temperature according to material types (e.g., about 120 - 150°C for PE films, 150 - 180°C for composite films).​

• Check the air pressure system to ensure stable pressure between 0.4 - 0.6MPa, and regularly polish or replace worn heat-sealing molds.​

• Optimize the control program to synchronize heat-sealing time with operation speed.​

• Store materials in a dry environment and test material sealing performance before production.​

2. Wrinkles or Bubbles in Sealing​

Main Causes:​

• Unstable film feeding tension (excessive tension stretches the material, while insufficient tension causes sagging).​

• Uneven heat-sealing mold surface or foreign matter residue.​

• Deviation in the synchronization of transverse sealing knives and longitudinal sealing rollers.​

Solutions:​

• Calibrate the tension control system, preferably using a closed-loop control with magnetic powder brakes and tension sensors.​

• Clean the mold surface before each operation and check mold flatness monthly (error ≤ 0.05mm).​

• Recalibrate the synchronization parameters of transverse and longitudinal seals through the teaching mode.​

II. Deviation in Bag Length and Cutting Abnormalities​

1. Unstable Bag Length Dimensions​

Main Causes:​

• Malfunction of color mark sensors (lens contamination, incorrect installation angle, sensitivity drift).​

• Abnormal signals from the film feeding motor encoder (loose coupling, dust accumulation on the encoder).​

• Improper gap between the film pulling roller and the pressing roller, causing material slippage.​

Solutions:​

• Clean the sensor lens every shift, adjust the installation angle to the optimal 45° detection position, and calibrate sensitivity regularly.​

• Tighten the motor coupling and clean the encoder with compressed air quarterly.​

• Adjust the roller gap to 1.2 times the material thickness, measured with a feeler gauge.​

2. Uneven Cuts or Blade Sticking​

Main Causes:​

• Excessive or insufficient temperature of hot cutting knives (too high causes material adhesion, too low results in rough edges).​

• Wear of cold cutting knife edges (bluntness > 0.3mm) or incorrect installation angle (cutting angle should ≤ 15°).​

• Parallelism error between the cutting knife and the bottom mold (offset cutting occurs when the error exceeds 0.1mm).​

Solutions:​

• Set a reasonable hot cutting temperature, 10 - 20°C lower than the material melting point, and equip with an automatic temperature compensation system.​

• Check blade wear weekly and repair with specialized grinding tools, maintaining a blade angle of 30°±2°.​

• Use a feeler gauge to calibrate the parallelism between the cutting knife and the bottom mold, controlling the error within 0.05mm.​

III. Feeding and Filling Failures​

1. Fluctuations in Material Filling Volume​

Main Causes:​

• Calibration deviation of metering devices (wear of impellers in volumetric metering, drift of sensors in weighing metering).​

• Blockage in the feeding channel (material agglomeration or adhesion due to excessive humidity).​

• Inadequate bag opening (insufficient suction nozzle air pressure or offset position).​

Solutions:​

• Calibrate the metering system every shift using standard weights or measuring cups, and regularly replace worn metering components.​

• Install a material screening device, control incoming material moisture ≤ 8% (adjust according to material characteristics), and configure an automatic material clearing vibration device.​

• Adjust suction nozzle air pressure to 0.3 - 0.4MPa and monitor bag opening width with a vision system (≥ 30mm).​

2. Material Leakage or Spillage​

Main Causes:​

• Asynchronous bag opening time and feeding action (premature opening leads to dust spillage).​

• Insufficient clamping force of the bag clamping device (aging of cylinder seals, wear of clamping jaw gaskets).​

• Bag movement during filling (loose film feeding positioning system).​

Solutions:​

• Optimize the PLC control program, setting the bag opening signal to lag the positioning signal by 50 - 100ms.​

• Replace cylinder seals and regularly check clamping jaw gaskets (replace when wear > 2mm).​

• Tighten the base bolts of the film feeding servo motor and calibrate the positioning system accuracy quarterly (error ≤ 0.2mm).​

IV. Electrical and Control System Failures​

1. Abnormalities in Human-Machine Interface (HMI) Operation​

Main Causes:​

• Touchscreen calibration offset (coordinate drift after long-term use).​

• Poor contact of communication cables (loose RS485/Profinet interfaces).​

• Logic errors in the control program (parameter conflicts after version upgrades).​

Solutions:​

• Perform touchscreen calibration monthly and use a dedicated stylus for operation.​

• Reinforce cable connections and use anti-bending cable protection sleeves (bending radius ≥ 6D).​

• Backup the original program and conduct simulated trials before upgrades.​

2. Abnormal Alarms of Servo Motors​

Main Causes:​

• Overload protection activation (mechanical blockage causing torque overload).​

• Encoder battery failure (memory loss in absolute encoders).​

• Poor heat dissipation of the driver (blocked fan, cabinet temperature > 40°C).​

Solutions:​

• Check the transmission system for foreign objects, and readjust the mechanical load (set torque limit to 1.5 times the rated value).​

• Replace encoder batteries annually (preferably with original manufacturer parts) and perform origin reset after replacement.​

• Clean the driver fan quarterly and install a cabinet air conditioner to maintain a temperature of 25±5°C.​

V. Preventive Maintenance Strategies​

1. Establish a Three-Level Maintenance System:​

• Daily Maintenance: Clean molds, lubricate guide rails with food-grade lubricants, and check sensor status every shift.​

• Weekly Maintenance: Calibrate the metering system, test emergency stop functions, and check cable connection tightness.​

• Annual Maintenance: Replace seals, fully lubricate transmission components, and update control software versions.​

2. Key Component Spare Parts Management: Maintain safety stocks for critical components such as heat-sealing molds, cutting knives, sensors, and servo drivers, and set replacement cycles (e.g., replace cutting knives after 200 hours of cumulative use).​

3. Operator Training: Conduct "Three Understandings and Four Abilities" training (understand structure, principles, performance; be able to operate, maintain, inspect, and troubleshoot), and implement an operation log system.​

Conclusion​

The stable operation of pouch packing machines relies on precise parameter settings, good equipment maintenance, and standardized operation management. By analyzing key aspects such as sealing quality, bag length control, material filling, and electrical systems, and combining preventive maintenance measures, companies can effectively reduce equipment failure rates and improve packaging quality and production efficiency. Enterprises should develop personalized troubleshooting solutions according to their product characteristics (such as material form, packaging materials, and production capacity requirements) and, if necessary, maintain technical cooperation with equipment manufacturers to continuously optimize equipment performance.