In continuous production, how to determine whether the heat sealing temperature is in a stable state? only by the temperature gauge?
答：
Not reliable. The temperature gauge shows the internal temperature of the heating block, but it is the transient temperature on the sealing surface that actually affects the seal.
Solution:
Heat sealing test paper method: Place the temperature-sensitive test paper on the sealing area, and determine whether the actual temperature distribution of the seal is uniform based on the color changes. The test can be conducted by the heat seal tester LTH-H3 (https://www.linktesting.org/891.html/heat-seal-tester-lth-h3/)
Strip force online sampling inspection: Take samples for testing the sealing strip force every hour, record the corresponding temperature and pressure values, and establish a process control chart (such as Xbar-R chart). Once there is an abnormal fluctuation in the strip force (such as a sudden drop or increase), it should be immediately investigated. The test can be conducted by the tensile tester XLW-500N(https://www.linktesting.org/7007.html/automatic-tensile-tester-xlw-500n/)
Why is it that for the same equipment and the same material, but sealing performance in day is better in night is poor?
答：
This is usually not a problem with the materials, but rather caused by the dew point of the compressed air or fluctuations in pressure. During the low-demand period of night shifts, the total pressure of the factory's gas source may increase, or the dryer may not be fully regenerated, resulting in an increase in moisture in the compressed air.
Solutions:
Check whether the compressed air pressure at the input end of the equipment is stable during the night shift (it is recommended to install a pressure stabilizer).
Test the dew point temperature of the compressed air. If it is higher than 4℃, it indicates excessive moisture. During heat sealing, water vapor will form tiny bubble channels.
Install a three-piece air source assembly (filter + pressure reducing valve + oil mist generator) before the heat sealing cylinder and drain the water regularly.
Record the actual values of the process parameters for each shift, rather than relying solely on the set values.
For aluminum foil bags, how can the sealing integrity be checked without damaging the packaging?
答：
The aluminium foil layer conducts electricity, so the conventional vacuum attenuation method cannot be used.
Solution:
Negative pressure vacuum method:
Principle: Negative pressure is applied to the packaging. If the seal is not tight, leakage points will be affected by the intake of the test liquid.
Applicable: Fast detection speed, and it will not cause damage to packages that are not leaking. The test can be conducted by Leak tester LTY-01 (https://www.linktesting.org/903.html/leakage-tester/)
How can we avoid the waste of costs caused by "excessive packaging" while ensuring the safety of the sealing?
答：
The design of the sealing strength of the risk is crucial, rather than blindly thickening the material or increasing the heat sealing temperature.
Solution:
Determine the minimum necessary sealing strength:
Based on the package weight, stacking height, and transportation vibration conditions, calculate the actual maximum peel force it can withstand (for example: a 2kg package may only require a sealing strength of 30N/15mm).
Quick verification method:
Prepare sample bags with different sealing strengths (such as 20, 30, 40, 50 N/15mm), conduct transportation simulation tests and drop tests, and determine the lower limit value that exactly meets the requirements. The test can be conducted by heat seal tester LTH-H3(https://www.linktesting.org/891.html/heat-seal-tester-lth-h3/) and tensile tester XLW-500N(https://www.linktesting.org/7007.html/automatic-tensile-tester-xlw-500n/)
Material thinning:
If the current sealing layer is 70 μm and the actual sealing strength is much higher than required (for example, 80 N), you can try reducing it to 50 μm while maintaining the anti-contamination property.
Equipment capacity matching:
Do not excessively increase the temperature or pressure in pursuit of high intensity. Doing so will instead cause the root to crack or the material to degrade, resulting in a loss that outweighs the gains.
The blister packaging (PTP) of medicines often has the problem of weak heat sealing between the aluminum foil and the PVC sheet. How to solve it?
答：
The PTP packaging is a type of inter-material heat sealing (aluminum foil coated with heat sealing adhesive layer vs. PVC hard sheet). The root cause of the problem lies in the mismatch between the activation temperature of the heat sealing adhesive layer and the softening point of PVC.
Solution:
Material side:
Confirm the type of heat-sealing adhesive applied to the aluminum foil (such as VC adhesive or acrylic adhesive), and its demolding temperature should be 5-10℃ lower than the Vicat softening point of PVC.
Check whether the gluing amount of the aluminum foil is uniform (recommend ≥ 3g/m²). A too thin gluing layer may result in partial missealing.
Device side:
The intermittent heat sealing method is adopted to give PVC sufficient time to soften and flow, avoiding insufficient heat accumulation caused by rapid and continuous sealing.
The surface of the heat sealing plate should be smooth and corrosion-resistant, and the residual glue and dirt should be cleaned regularly.
Verification method:
In addition to the peel strength test, the dye penetrant method should also be conducted: immerse the blister in the methylene blue solution, then evacuate the air and observe whether the tablet is stained. This method can more sensitively detect micro-leaks. The leak test can be conducted by the leak tester LTY-01(https://www.linktesting.org/903.html/leakage-tester/). The peeling test can be completed by the tensile tester XLW-500N(https://www.linktesting.org/7007.html/automatic-tensile-tester-xlw-500n/)
