Identify the liner
Provide the exact film material and thickness; visual appearance alone is not enough.
Material & process guide
Seal the PE liner before finishing the outer bag.
In a lined sack, the product-contact liner and the supporting outer bag perform different jobs. Confirm the liner material and seal test first, then define how the outer paper or woven bag will be folded or sewn.
01Bag structure
Liner resin, thickness, layers, gusset and contamination at the seal
02Required finish
Required seal width and whether the outer bag is sewn afterwards
03Line conditions
Temperature window, cooling, conveyor height and target output
01 · Selection path
Seal the PE liner before finishing the outer bag.
In a lined sack, the product-contact liner and the supporting outer bag perform different jobs. Confirm the liner material and seal test first, then define how the outer paper or woven bag will be folded or sewn. Selection guidance, not a performance guarantee.
Test the seal result
Use real filled-bag conditions to check cleanliness, seal continuity and cooling.
Finish the outer bag
After the liner route is confirmed, define folding, sewing, tape and thread trimming for the support bag.
02 · FIT CHECK
Where this process fits
Selection guidance, not a performance guarantee.
Good starting conditions
- The liner material is compatible with controlled heat sealing
- The seal area can be presented clean and sufficiently flat
- A real liner sample and required seal result are available
Confirm another process when
- The film material or layer structure is unknown
- Product dust or folds cannot be controlled in the seal area
- The required barrier result has not been verified by sample testing
03 · EQUIPMENT
Related equipment
Selection guidance, not a performance guarantee.
04 · DIRECT ANSWERS
Questions buyers ask
Selection guidance, not a performance guarantee.
Should the PE liner be sealed before sewing the outer bag?
When the liner provides the product-contact barrier, its seal is normally defined and tested separately before the outer bag is finished. Confirm the exact sequence with the sample.
Can sealing temperature be chosen from the bag photo?
No. Material, thickness, layers, speed and cooling affect the usable window, so the setting must be confirmed by testing.
Why is cooling relevant after heat sealing?
Cooling helps the heated seal stabilize before it is pulled, folded or moved to the next operation.
What causes an inconsistent liner seal?
Wrinkles, product contamination, uneven presentation, material variation and unsuitable heat or speed settings can affect consistency.
Prepare the bag data before asking for a quote
Send the bag material, layers, width, filled weight, target output, voltage and a photo of the required finished closure.