During the production process, the quality of the finished product should be constantly checked. In addition to the size and appearance visual inspection, the sealing strength and sealing performance must also be checked. If problems are found, make timely adjustments and make detailed records. Taking the three-side sealing zipper bag as an example, the following items should be checked:
1. Heat sealing strength;
2. The size, flatness, appearance quality of the bag, front and back alignment of the bag and other customer requirements, such as the position of the tear opening, etc.; the direction of the zipper, especially in the zipper connection section;
3. The internal and external opening force of the zipper, the internal opening force of the PE zipper is generally required to be ≥50N/50mm, the internal opening force of the PP zipper is generally required to be ≥60N/50mm, and the PE LL-201 of Shanghai Yifu Packaging Products Co., Ltd. can reach ≥70 N/50mm, PE Q501 can reach ≥80 N/50mm, and the external opening force has different requirements according to the customer's usage habits;
4. The sealing performance of the bag can be inspected by spraying a dye-added penetrant on the inside of the seal to see if it penetrates, or by hanging the bag with water upside down for 24 hours to see if it sees water;
5. The flatness of the bag zipper.
Heat-sealing bag making is a heat transfer process. The process is relatively uncomplicated, but there are many factors that affect its quality. In addition to the above points, the peel strength of the composite film, the heat resistance of the printing ink, and the heat-sealing layer additives Precipitation, the width of the heat-sealed edge, the thickness uniformity of the composite film, etc. are all related to the final quality of the composite film bag, and comprehensive consideration should be made in the production process.