Wet Wipe Packaging Machine – Common Packaging Machine Malfunction Issues

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Over time, wet wipe packaging machinery—especially when operating continuously under heavy loads—is prone to various electrical and mechanical failures, such as unreliable sealing, intermittent machine operation, blown fuses during startup, squeaking noises during running, uncontrolled temperatures, deformation or bending of finished bags at the sealing area, and the appearance of bubbles or irregular marks around the sealing blade imprint. Drawing from practical experience with packaging machines, this article analyzes the root causes behind several of these common issues and provides effective solutions. Additionally, it highlights essential maintenance practices for continuous sealing machines, aiming to offer valuable guidance to both businesses and individuals who rely on this equipment. 1. Unreliable Sealing

Wet Wipe Packaging Machine – Common Packaging Machine Malfunction Issues

Based on practical experience with packaging machines, this article analyzes the causes of several common malfunctions and provides corresponding solutions. It also discusses maintenance issues specific to continuous sealing machines, aiming to offer valuable guidance for businesses and individuals who rely on these machines.

1. Poor Sealing: Poor sealing is one of the common malfunctions in continuous sealing machines. "Poor sealing" can have three meanings:

① The sealing area of the packaging bag cannot be sealed properly;

② Under the pressure of the sealing knife, although the bag opening is sealed, a slight squeeze or tear will cause the seal to crack open again.

③ When a peel test is conducted on the sealing area, if half of the seal remains firmly intact while the other half has already separated, the packaging bag still fails to meet quality standards. This is because the contents are highly susceptible to leaking under pressure during storage and transportation. Such issues frequently occur when the composite liner material is OPP with an outer layer of blown PE.

The main causes of the first type of failure are as follows.

(1) Insufficient heat-sealing temperature: Typically, for composite bags with OPP as the inner layer, when the total bag thickness is between 80 and 90 μm, the heat-sealing temperature should reach 170–180°C. For composite bags with PE as the inner layer, where the total bag thickness ranges from 85 to 100 μm, the temperature should be maintained at 180–200°C. Importantly, whenever the total bag thickness increases, the heat-sealing temperature must also be adjusted upward accordingly.

(2) Sealing too quickly can also lead to improper sealing—this is directly related to the speed of the sealing machine. If the speed is set too high, the sealed area doesn’t have enough time to heat up before being pulled by the traction rollers and immediately transferred to the cooling section for rapid cooling. As a result, the seal simply won’t meet the required quality standards.

(3) The pressure of the cold-pressing rollers is improperly adjusted. There is one roller on the top and one on the bottom; the pressure between them should be just right. To adjust the pressure, simply tighten the spring.

(4) Poor-quality heat-seal film is often the culprit when seals fail—whether it’s due to inadequate sealing or outright inability to seal. If the corona treatment of the composite liner material is uneven, resulting in poor adhesion that happens precisely at the sealing area, the seal will inevitably fail. While this issue is relatively rare, when it does occur, the product is almost always scrapped. That’s why, in the color-printed packaging industry, downstream processes must closely monitor upstream ones; as soon as a quality problem is detected, it’s crucial to promptly analyze the root cause and take corrective action. Additionally, moisture or contamination at the sealing area can also lead to weak or incomplete seals. In general, to address the first type of sealing failure—where the seal isn’t strong enough—it’s usually effective to slightly increase the heat-sealing temperature, reduce the sealing speed, and simultaneously boost the pressure applied by the cooling press roller.

The main reasons for the second type of sealing failure are as follows.

(1) Insufficient heat-sealing temperature—simply increasing the heat-sealing temperature slightly will resolve the issue.

(2) The surface of the heat-sealing blade is uneven. The heat-sealing blade consists of two separate pieces—upper and lower—typically housing a thermocouple that monitors temperature transfer. There are three screws on the heat-sealing blade: the middle screw provides support and reinforcement for the blade, while the two outer screws are fitted with pressure springs and shims, primarily used to adjust the pressure applied by the blade. Each of the upper and lower blades also has two springs. The primary cause of an uneven blade surface is either the middle screw being installed at an angle (rather than horizontally) or uneven pressure from the upper blade’s pressure spring. To resolve this issue, first realign the middle screw so it sits perfectly horizontal. If the upper and lower blades are misaligned, simply adjust the pressure springs until the balance is just right. Specifically, when the spring is loosened outward, the heat-sealing blade will drop slightly; conversely, tightening the spring on the lower blade will lift the blade upward.

(3) Uneven pressure from the cold-pressing roller—just like in the first scenario—can also lead to unreliable sealing. The solution is similar to that used for the initial issue.

The primary reasons for the third type of sealing failure are twofold.

(1) Uneven heat-sealing blade pressure or uneven cold-press blade pressure—note that the adjustments for both the heat-sealing and cold-press blades are completely identical.

(2) The surface of the heat-sealing blade is not smooth enough; refer to the corresponding solution for the second type of sealing failure—poor seal strength.

2. Fuse Blown: The primary function of the sealer machine’s motor is to drive the gearbox and ensure proper gear transmission among its various components. Occasionally, when the sealer is first turned on, it emits a "squeaking" sound, preventing it from operating normally—and in some cases, even causing the fuse on the live wire to blow. To troubleshoot this issue, start by verifying that the power supply is functioning correctly. Next, disconnect the power and use the resistance setting on a multimeter to check whether the switch itself is damaged. Additionally, carefully inspect the wiring and the motor for any signs of short circuits. Typically, if the motor is short-circuited, its windings are burned out, or there’s an open circuit, the fuse will blow as soon as the sealer is switched on. Another common cause of this problem is using a fuse with an inadequate amperage rating; simply upgrading to a properly sized fuse should resolve the issue.

3. A "squeaking" sound occurs during operation. This issue arises while the sealing machine is running; the squeak usually happens suddenly, followed by uneven sealing speeds. As a result, the seal on the packaging bag develops poor-quality embossed patterns, negatively impacting the product's visual appearance. Occasionally, the machine may even function normally for a short time, but its performance remains highly inconsistent.

This phenomenon is most often caused by severe mechanical damage or wear, as well as inadequate lubrication. First, locate the faulty area by tracing the source of the noise. After removing the back protective panel, we discovered that the "squeaking" sound was coming from inside the gearbox. By carefully unscrewing each retaining bolt one by one, we noticed that the grease inside the gearbox had completely dried out, leaving the gears gleaming brightly—clear evidence that the root cause of the problem was a lack of proper lubrication. To resolve the issue, we mixed the same type of motor oil with fresh grease and carefully refilled it into the gearbox. Finally, after tightening all the screws to secure everything back in place, we restarted the machine—and sure enough, the annoying "squeaking" sound disappeared, and the system now operates smoothly as usual.

Additionally, if the high-temperature belt joint is loose, severely worn, dirty, or has debris on its surface, it may fail to synchronize with the traction wheel during operation—and in some cases, this can even cause a "squeaking" noise. To resolve this issue, simply replace the high-temperature belt with one of the same specifications. Replacing the high-temperature belt does require a bit of skill. First, use your hand to compress the pressure wheel spring. Then, carefully place one end of the belt onto the drive pulley, while holding the other end steady against the opposite pulley by hand. Set the speed regulator to low speed, and as soon as you start the system, the belt will automatically snap into place due to its own momentum. Occasionally, the "squeaking" sound may also originate from a DC shunt motor—likely because the motor bearings are running dry. If this is the case, disassemble the motor, lubricate the bearings thoroughly, and the noise should disappear.

4. Loss of Temperature Control in Sealing: This issue manifests as a malfunctioning temperature display, making it impossible to regulate the sealing temperature. The heat-sealing temperature becomes inconsistent—resulting either in scorching at the seal or, conversely, weak and poorly bonded seals that are oddly deformed and visually unappealing. The primary cause of this failure is typically a faulty thermometer, which must be repaired or replaced. Additionally, the thermocouple might also be damaged, preventing it from accurately transmitting the sensed temperature to the thermometer. Replacing the thermocouple with one of the same model and specifications should resolve the problem. Mechanically, uneven heat-sealing pressure could be the culprit. To address this, simply adjust the pressure springs on the sealing blade to ensure consistent pressure across the entire surface. At the same time, keep the contact surface of the sealing blade clean and free of any dirt or debris. Lastly, another potential cause is poor thermal sealing quality inherent in the composite material itself. If the material’s heat-sealing coefficient has changed, it may lead to inconsistent temperature distribution during the sealing process, resulting in unevenly sealed edges.

5. Sealing Machine Stutters and Stops During Operation During production, we encountered a common issue where the sealing machine would intermittently stop and start, with inconsistent speeds. Upon disassembling the back panel of the machine, we discovered that the connection points between the motor shaft and the gearbox had become loose and misaligned. By carefully tightening all the screws to ensure proper alignment, we were able to resolve the problem. Additionally, the main motor relies on carbon brushes making contact to operate. If the carbon brushes are severely worn, failing to maintain full contact with the slip rings or experiencing poor friction, this can also cause the sealing machine to stutter and stop. Replacing the carbon brushes with new ones of the same model promptly resolves the issue.

6. Bubbles and irregular marks appear at the sealing area—this issue is also quite common. While it doesn’t cause leakage of the packaged contents, it does detract from the aesthetic appeal of the packaging and undermines the product’s overall image. The primary causes of this defect are as follows: (1) Over time, dust and plastic debris accumulate on the heated sealing belt due to prolonged equipment use, leading to an uneven, rough surface. This results in inconsistent heating during sealing, causing bubbles to form after the seal is pressed by the cooling roller. To resolve this, simply clean the sealing belt or replace it entirely. Typically, the sealing belt is about 1.5 cm wide and roughly 22 μm thick; if contaminants become too stubborn to remove through cleaning, the belt must be discarded. (2) Irregular, uneven indentations on the cooling pressure roller directly transfer onto the packaging, creating noticeable marks along the sealed edges. To ensure the packaging maintains a neat and professional appearance, it’s best to replace the cooling pressure roller altogether.

7. Key Considerations for Packaging Machine Maintenance (1) The sealing machine should be placed in a well-ventilated, dry area; ideally, maintain the room temperature around 25°C. (2) After every 48 hours of operation, lubricate all moving parts with No. 6 oil—particularly at gears, bearings, and the gearbox. (3) Regularly remove dust to keep the entire machine clean. When not in use, it’s best to unplug the power supply and cover the machine with a protective cloth. (4) If the machine runs continuously for an extended period, turn on the cooling fan before shutting it down. Allow the temperature to drop completely before powering off, as failing to cool down first can easily damage the heating element due to residual heat. (5) Periodically clean dirt and debris from the heating element to ensure optimal sealing quality. (6) Replace severely worn components promptly to extend the overall lifespan of the machine.