Views: 0 Author: Site Editor Publish Time: 2025-06-30 Origin: Site
The sealing performance of the transparent film three-dimensional packaging machine directly affects the moisture-proof, anti-oxidation and anti-pollution capabilities of the product, and it is the core indicator of packaging quality. Comprehensive control is required from multiple dimensions such as membrane material selection, equipment adjustment, process optimization, process monitoring and maintenance management. The following analysis is conducted from four aspects: influencing factors of sealing performance, guarantee methods, solutions to common problems, and long-term stability maintenance.
Membrane material characteristics
Heat sealing performance: The melting point, heat sealing strength and heat adhesion of the membrane material directly affect the sealing quality. If the thickness of the heat seal layer of the membrane material is insufficient or the formula is unreasonable, it may cause the seal to crack easily.
Uniformity of thickness: If the thickness deviation of the membrane material exceeds ±5%, it will cause uneven local heating during heat sealing, resulting in false sealing or missed sealing.
Puncture resistance: Insufficient strength of the membrane material may cause it to be punctured during transportation or stacking, thereby damaging the sealing property.
Equipment structure and operation
Heat sealing knife: The material, flatness and heating uniformity of the heat sealing knife directly affect the sealing quality. If the surface of the heat sealing knife is uneven or the heating tube ages, it will lead to insufficient sealing strength.
Pressure control: Insufficient or uneven heat sealing pressure can lead to poor sealing, while excessive pressure may puncture the film material.
Cooling system: Insufficient cooling can cause the membrane material at the sealing area to not be fully cured, making it prone to cracking during subsequent processing.
Process parameter matching
Temperature and time: If the heat sealing temperature is too high or the time is too long, the film material will degrade. If the temperature is too low or the time is too short, the sealing will not be firm.
Tension control: Fluctuations in the tension during the transportation of membrane materials can cause the sealing position to shift or the membrane material to stretch, affecting the sealing performance.
Sealing width: Insufficient sealing width (such as less than 3mm) will reduce the sealing strength and increase the risk of air leakage.
Membrane material selection and adaptation
Heat seal layer optimization: Select film materials with high heat seal strength (≥15N/15mm) and good heat adhesion, such as composite films (BOPP/PE, PET/PE).
Uniformity control of thickness: The thickness deviation of the membrane material should be within ±3% to avoid poor local heat sealing.
Enhanced puncture resistance: For sharp products, select composite films with a thickness of ≥50μm or with an added nylon (PA) layer.
Equipment adjustment and improvement
Optimization of heat sealing knife
Regularly check the flatness of the heat sealing knife. Use a micrometer for measurement, and the deviation should be controlled within ±0.02mm.
Replace the aged heating tubes to ensure the uniformity of the surface temperature of the heat sealing knife (temperature difference ≤±2℃).
Pressure control system upgrade
Pneumatic or hydraulic pressure control systems are adopted to ensure uniform distribution of heat sealing pressure (deviation ≤±5%).
Elastic buffer pads are added on both sides of the heat sealing knife to compensate for the fluctuation of the film material thickness.
Cooling system enhancement
Add a cooling air knife or water cooling device to ensure that the membrane material cools to room temperature within 1 second after sealing.
Regularly clean the cooling air ducts to prevent dust blockage and affect the cooling efficiency.
Refinement of process parameters
Temperature and time matching:
The optimal heat-sealing parameters were determined through experiments. For example: for 25μm BOPP/PE film, the heat-sealing temperature was 160-165℃ and the time was 0.8-1.0 seconds.
The segmented heating technology is adopted. The temperature at the front end is slightly higher (such as 165℃) to ensure a firm seal, while the temperature at the rear end is slightly lower (such as 160℃) to prevent the degradation of the film material.
Tension closed-loop control
Tension closed-loop control is achieved by using tension sensors and magnetic powder brakes/clutches, with fluctuations controlled within ±3%.
Add floating rollers along the membrane material conveying path to buffer tension fluctuations.
Sealing width design:
Design the sealing width according to the product size. It is recommended to be ≥5mm to ensure the sealing strength.
Regularly check the width of the sealing knife and replace it in time when it is worn.
Process monitoring and detection
Real-time sealing quality inspection
Install infrared sensors or thermocouples to monitor the heat sealing temperature. An automatic alarm will be triggered when the deviation exceeds ±2℃.
Monitor the heat sealing pressure using a pressure sensor. Adjust it when the deviation exceeds ±5%.
Finished product sealing performance test
Randomly inspect the packaged finished products. Use the negative pressure method (such as -50 kpa) to detect air leakage. A pressure drop of no more than 5kPa within 30 seconds is considered qualified.
Use the visual inspection system to check the integrity of the seal and remove products with loose seals or burrs.
The seal is cracked or loosely sealed
Reasons: The heat sealing temperature is too low, the pressure is insufficient, and the heat sealing layer of the membrane material is thin.
Solution: Increase the heat sealing temperature by 5-10℃, raise the pressure by 10-15%, and replace the film material with a thicker heat sealing layer.
The membrane material at the sealing area is melted through
Reasons: Excessively high heat sealing temperature, excessive pressure, and poor heat resistance of the film material.
Solution: Reduce the heat sealing temperature by 5-10℃, decrease the pressure by 5-10%, and select membrane materials with better heat resistance.
The seal is not tight or there is air leakage
Reasons: Membrane material contamination, uneven surface of the heat sealing knife, insufficient cooling.
Solution: Clean the surface of the membrane material, repair or replace the heat seal knife, and extend the cooling time to more than 2 seconds.
Offset of the sealing position
Reasons: Fluctuations in membrane material tension, non-parallel guide rollers, and wear of the cutting knife.
Solution: Optimize tension control, adjust the parallelism of the guide roller, and replace the cutting knife.
Daily maintenance
Cleaning: Clean the heat sealing knife, cutting knife and guide roller daily to prevent the accumulation of glue residue or film debris.
Lubrication: Lubricate the transmission components (such as chains and gears) weekly using high-temperature resistant grease.
Inspection: Check the membrane material conveying path daily to ensure there is no jamming or wear.
Regular calibration
Heat sealing tool calibration: Use a micrometer to check the flatness of the heat sealing tool every month. Make adjustments when the deviation exceeds 0.02mm.
Sensor calibration: Calibrate the temperature sensor, pressure sensor and visual inspection system every quarter to ensure measurement accuracy.
Cooling system calibration: Check the cooling air ducts and air velocity every six months to ensure cooling efficiency.
Spare parts Management
Key spare parts reserve: Stock commonly used spare parts (such as heat sealing knives, cutting knives, heating tubes) to ensure timely replacement in case of failure.
Spare parts quality: Select spare parts that match the original equipment to avoid affecting the sealing performance due to spare parts quality issues.
Technological upgrade
Automation control: The introduction of PLC and touch screen enables automatic adjustment of heat sealing parameters and self-diagnosis of faults.
Online inspection system: Install high-precision visual inspection and negative pressure inspection devices to monitor the sealing performance in real time and automatically remove non-conforming products.
Process optimization
Segmented heat sealing and cooling: The heat sealing process is divided into three stages: preheating, main sealing, and cooling to reduce local overheating and insufficient cooling.
Double-seal design: For products with high sealing requirements, a double-seal design (such as one transverse seal and one longitudinal seal) is adopted to enhance redundancy.
Personnel training
Operation training: Regularly train operators to master the skills of equipment adjustment, parameter setting and troubleshooting.
Quality awareness: Strengthen the quality awareness of operators to ensure that operations are carried out in accordance with standards.
The sealing performance guarantee of the transparent film three-dimensional packaging machine needs to be comprehensively optimized from multiple aspects such as film material, equipment, process, monitoring and maintenance. By choosing high-sealing membrane materials, optimizing heat sealing and cooling processes, upgrading equipment control systems, strengthening daily maintenance and real-time detection, the sealing performance of packaging can be significantly improved. Operators must strictly abide by the operating procedures, promptly identify and solve problems, and continuously improve the sealing quality in combination with technological upgrades.