Post-printing and post-lamination processes are the entire sequence that transforms the printed and laminated film roll into the final consumer-ready bags. These processes are often overlooked by buyers. Customers usually focus only on the print quality and design, unaware that cutting, bag forming, and inspection are critical to determining the final yield, sealing quality, and delivery time. This article takes common bag types such as three-side sealed bags, stand-up bags, and zipper bags as examples, and comprehensively dissects the processes after printing and lamination.Post-Packaging ProcessesHelp you understand the production cycle and quality control points of the factory, so you can spend your time and budget effectively when customizing.
1. Slitting: Cutting the wide film into the appropriate width
Composite and printed film rolls are often wider than one meter, while individual bags are typically only a few tens to several dozen centimeters wide. Therefore, the first step in the subsequent process is slitting. The slitting machine cuts the wide film roll into several narrower rolls according to the order specifications, while simultaneously removing the waste edges and controlling tension.
The quality of the slit film directly affects the subsequent bag-making process. Film reels with uneven ends or inconsistent tension are prone to misalignment and wrinkling when loaded onto the bag-making machine, leading to an increase in defective products. Additionally, the number of joints and the loss rate during slitting are important indicators for cost control in the factory. When purchasing, it is advisable to pay attention to the yield rate parameter, as it often reflects the factory’s management level.
II. Bag Making: The Core Process for Determining Bag Type and Sealing
Bag forming is the core of the packaging finishing process. The bag forming machine takes the slit film roll and forms it into finished bags through heat sealing and cutting: three-side sealed bags, back-sealed bags, self-standing bags (with a pleated bottom), eight-side sealed bags, zipper bags, and suction mouth bags, each corresponding to different bag forming machines and mold configurations.
Heat sealing is a critical technology in the bag-making process, where temperature, pressure, and speed must be properly matched. Too low a temperature results in weak seals, while too high a temperature can cause blistering or even burn through the film. Accessories such as zippers, suction nozzles, and exhaust valves are also fixed onto the bag body during this heat sealing process. The accuracy of accessory positioning directly affects the user experience and sealing performance. For a deeper understanding of the most basic bag types, you can check our previous content.Three-Side Sealing Bag Explanation。
III. Inspection: The Final Defense Before Shipment
The inspection process in the final packaging stages determines the quality of products entering the market. Modern bagging machines are commonly equipped with online inspection systems: photoelectric eyes track color markers, and heat seal detection devices monitor the quality of the sealing in real time, automatically stopping the machine and issuing alarms when issues are detected.
After finished products are off the production line, there is also a factory release inspection, including appearance checks (color difference, surface scratches, dirt), dimensional sampling, seal strength testing, leakage testing (air leakage check), and drop testing. Reputable manufacturers will follow the AQL sampling standards and issue a factory release inspection report. When placing bulk orders, it is recommended to clearly specify that each batch should come with a test report, which is the most convenient way to ensure quality.
Four. Packaging, Warehousing, and Shipment Management
Pass the inspected finished bags to the packaging process: counting, bagging, and boxing. The outer boxes usually require moisture-proof measures. Especially for export sea freight orders, poor moisture-proof packaging can lead to bags getting damp and moldy in the container, resulting in significant losses.
After warehousing, products are managed by batch, with records of production dates, raw material batches, and inspection results to achieve full traceability. In the event of quality issues at the terminal, the specific batch and process can be quickly identified. The traceability system is also a mandatory item checked by food-grade customers during factory audits.
Five. How Do Post-Processing Steps Affect Delivery Time
Many customers believe that delivery time mainly depends on printing, but in reality, the bag-making process is often the production bottleneck. The speed of the bag-making machine, the order quantity, and the time required to switch molds and auxiliary materials during changeovers all affect the overall delivery time. During peak seasons, bag-making capacity is tight, making it difficult to accommodate rush orders, and delivery times fluctuate more significantly.
It is recommended to reserve sufficient time for downstream processes when placing an order: the standard bag making cycle usually takes 3 to 7 days, and orders with zippers, air valves, or irregular structures may take longer. Include time for cutting, bag making, inspection, and packaging storage in your schedule to avoid delivery delays.
Summary and Recommendations
Although the post- packaging processes are behind the scenes, they directly determine whether the bags are functional, the sealing reliability, and whether the delivery schedule is accurate. When selecting a factory, in addition to checking printing capabilities, it is essential to evaluate the number of bag-making equipment, inspection procedures, and batch management capabilities. Only by comprehensively assessing the front-end processes such as lamination and printing together with the back-end processes can you find a truly reliable partner. For details on the front-end processes, you may refer to ourComposite Packaging Process OverviewandComplete Guide to Packaging Printing ProcessesIntegrate the front and back sections to fully understand the entire production line.
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