Single-use seasoning sachets may seem simple at first glance, but the real challenge lies in the interplay between weight accuracy, easy tearing, and packaging stability. Increasing the bag width improves weight consistency, but shifts the tear line away from the sealing edge. Widening the seal reduces air leakage, but reduces the available volume for powder. Domestic manufacturers of small seasoning sachets often struggle with these three variables, repeatedly adjusting samples during the trial process. This article breaks down the process of setting specifications in sequence and provides the key items to record during sampling.
Why does the accuracy of weight affect sealing and tearability?
Key Points
- Changing the bag width incurs the highest cost. First determine the bag width, then calculate the weight and sealing width accordingly.
- The weight accuracy is determined by the weight distribution of continuous production, not by a few samples on the sample table.
- The tear position should be confirmed together with the sealing edge and the tear resistance direction of the film.
- Among the four variables affecting filling stability, the drop height and film feeding condition should be prioritized.
The weight is not an independent indicator. For the same bag type, if the bulk density of the powder changes, the weight of the same volume will vary. Products with larger weight deviations often require more internal bag space to accommodate fluctuations, and as the internal bag space increases, the distribution of powder inside the bag becomes less uniform, making it easier for powder to accumulate at the bag opening before sealing.
The tear notch follows the same logic. The tear is guided by the initial notch along the sealing edge. If the weight is inconsistent, causing the actual sealing position of each package to fluctuate within the allowable range, the position of the tear relative to the seal becomes variable. When consumers try to open the package, they either cannot tear it or end up tearing directly into the bag body. These three variables interact with each other on the same graph and must be determined together.
Why should we first determine the bag width before setting the weight?
The recommended sequence is to first determine the bag width, then work backward to calculate the weight and sealing width. The bag width determines the size of the forming tool on the packaging machine and the cycle time for one forming operation; changing the bag width incurs the highest cost. The weight can be adjusted by modifying the feeding volume and powder density, which has relatively lower cost. The sealing width and tear position belong to the mold and printing scope, with moderate modification costs.
The selection of bag width should be based on two limitations. First, the volume of the product corresponding to a single dose, plus the allowance for powder bulk angle. Second, the specifications of the forming tool on the packaging machine; it is usually more economical to make minor adjustments based on existing specifications rather than retooling. After determining the bag width, calculate the discharge volume using the measured bulk density, and then create a volume-to-weight reference table for direct use during production.
Where should the tear notch be placed for optimal results?
Side-opening tear notches on the short edge are generally more convenient, as they have a shorter tear path and a clear direction of force, making them safer for fine powder contents and less likely to squeeze out powder when opening. In contrast, packaging with side-opening tear notches on the long edge appears wider on the shelf, but the tear path is longer. If the tear direction of the film is not suitable, it may result in diagonal tearing.
The depth and number of tear notches should also be adjusted according to the bag width. For narrow bags, making small notches on both sides is often more reliable than a single deep notch on one side; for wide bags, the position of the notches relative to the transverse seal should be confirmed to ensure the tear progresses straight along the edge of the seal. These details are related to the bag type and seal shape. You can first refer to the station’s information on…Three-Side Sealed Bag TypePlease refer to the instructions and confirm based on your own mold.
Filling stability depends on which variables?
On-site stability mainly depends on four variables. The first is the feeding method. Screw feeding measures by volume, and fluctuations in powder density will directly affect the weight; whereas weighing feeding offers higher accuracy but slower cycle time. The second is the feeding height difference. The greater the height difference, the more the powder will fly inside the bag, leading to more contamination at the bag opening.
The third factor is the film tension and friction coefficient. If the film runs unevenly on the forming drum, it will cause intermittent misalignment, leading to displacement of the sealing position. The selection of inner layer material for the wound film and the level of release agent will both affect this factor. Related judgments can be referred to within the station.Food Grade Roll Film Material SelectionThe fourth step is cleaning and cooling of the sealer. After continuous operation for a shift, powder accumulation on the jaws and temperature drift will cause a decline in sealing quality.
Sample Confirmation Checklist
- Run the actual powder continuously for a period, recording the weight distribution of 100 consecutive packages, rather than weighing only a few samples.
- Record the sealing temperature, pressure, and time based on actual line speed, and schedule a shutdown midway to observe the first few packages after restarting the machine.
- The offset between the tear position and the seal is measured at the start of the run and after one hour of operation.
- Seal appearance continuity and powder residue on the bag mouth, with samples retained at fixed intervals.
- Stability and stacking performance after being filled with actual products, checked again after a period of time.
- The number of samples required for the seal peel test should be sufficient to cover the entire production run, using a standardized method.
The test parameters for seal peeling will affect the readings. The sample width and stretching speed must be recorded; otherwise, data from different batches cannot be compared.ASTM F1929 A method for detecting the sealing channel using dye penetration testing is provided, suitable for confirming whether there are connected gaps inside the seal. The specific sampling quantity should be determined according to your acceptance criteria.
Conclusion
Single-use seasoning packet recommendations should be adjusted in the order of bag width, weight, and tear position, prioritizing the item with the highest modification cost first. Weight accuracy should be determined based on the weight distribution during continuous production, not just a few samples on the sample bench; tear performance should be confirmed in combination with the film’s tear resistance direction and notch position; and filling stability should first address the material drop difference and film feeding condition. When covering multiple formulas, they can be initially divided into two to three intervals based on density, with a fixed specification for each interval, then verifying the filling tolerance item by item. This approach of dividing into intervals for specification setting is applicable only when the density differences between formulas can be controlled in separate categories. Relevant bag types and material orientation can be combined accordingly.Seasoning and Sauce PackagingLet’s look at the overall approach together.
Common Questions
How many formulas can one specification of single-dose seasoning packet cover?
Typically, several formulas with similar bulk densities can be covered. The limitation lies in the filling tolerance: under the same volume, the greater the density difference, the larger the weight deviation. If the deviation exceeds the acceptable tolerance, separate specifications are required. In practice, it is recommended to divide the formulas into two to three intervals based on density, fix one specification for each interval, and then verify the filling tolerance for each formula individually. Fewer specifications are beneficial for changeovers, especially for lines producing small batches with multiple flavors. Specifications for small bags of flavoring are usually based on…Seasoning Packaging BagUse the existing bag type for the drop.
If the tear is difficult to open or torn unevenly, what should be adjusted first?
First check the relative position between the notch and the sealing edge, then consider modifying the notch shape. If the notch is too far from the sealing edge, the tear will not be guided by the sealing edge and may tear diagonally into the bag body. If the notch direction is inconsistent with the easy-tear direction of the film, it will result in difficulty tearing or stopping midway. After confirming these two factors, you can then evaluate the notch depth and whether a symmetrical notch should be added on the other side. Changing the film or modifying the structure is usually the last option, as it incurs the highest cost.
Dust often appears at the bag opening during filling. Which areas should be checked?
Check the material drop difference and powder dispersion first, then examine the static electricity. The closer the material discharge port is to the sealing area and the greater the drop, the higher the probability of powder falling into the bag opening. Fine powder generates static electricity during the film movement, which adheres to the inner surface of the film and is carried all the way to the sealing area. You can first modify the material discharge sequence to two stages, reducing the amount of material discharged each time, and then confirm whether ion wind is needed. It is also recommended to set the cleaning interval for the sealing jaws on a shift basis, rather than waiting for defects to occur before handling.
What is the appropriate sealing width for small pouch seasoning?
The sealing width depends on the bag width, powder flowability, and packaging machine accuracy, and there is no universal value. A wider seal can accommodate minor misalignment at the sealing position, reducing leakage, but it will occupy effective internal volume of the bag; this is particularly noticeable in narrow bags. The wider the seal, the less space is left for the powder, making weight control more challenging. It is recommended to first determine an initial ratio based on the bag width, then adjust according to the actual leakage rate and weight distribution during production, rather than directly copying values from other products.