Published · 5 min read
A PE bag punctured by a sharp component has not failed in the same way as a small edge nick that grows into a long tear. Treating both problems by simply adding thickness can increase material use without removing the cause. A useful investigation separates where damage starts, how it grows and which load is present, then connects those observations to film structure, bag geometry and the packing operation.
Puncture, impact and tearing are different events
Puncture is local penetration by a corner, burr or probe. Impact applies a load rapidly, so the film must deform and distribute energy. Tearing describes growth from an existing cut, pinhole or edge defect. A film can resist broad impact yet allow a notch to propagate easily; another structure may show the opposite balance.
A free-falling dart method estimates the missile mass at which half of the specimens fail under defined conditions. Initiated-tear methods examine resistance after a cut has already been introduced. Because specimen geometry, loading mode and reported result differ, these measurements are not interchangeable. Poşetsan Date therefore begins with the observed failure rather than the isolated question, “How many microns?”
Build a failure map before ordering a test
Collect damaged and undamaged packs from the same shipment or production lot. Holes repeatedly aligned with one product corner suggest a different cause from random pinholes across the bag surface. A split beginning beside a seal also needs to be separated from impact in the film body.
Mark the origin of each hole and the component touching that location.
Record whether damage first appears during filling, stacking, storage or transport.
Keep machine direction and transverse direction identifiable on samples.
Note temperature, storage time, pack weight and exposed sharp edges.
Retain sound control bags from the same manufacturing lot.
This map prevents a laboratory from producing a precise answer to the wrong question. It also reveals process causes such as a damaged guide, rough tote, excessive drop, tight bag fit or uncontrolled movement inside the pack.
Match the test to the decision
Free-falling dart impact
Does the film fail under a sudden, expanding impact? A dart test offers a controlled comparison. The value depends on the specified method, dart head, drop height, specimen thickness and preparation. Results from different configurations should not be placed in one ranking. Use the result as a comparative quality measure under matched conditions, not as a stand-alone guarantee that every packed product will survive its route.
Tear initiation and propagation
If a nick, perforation or small puncture grows during handling, tear testing becomes more relevant. The plan should include machine and transverse directions because orientation created during film manufacture can produce different directional behaviour. A method that creates a notch and a method that propagates a prepared slit do not describe exactly the same property. A purchase specification should identify the method, direction and acceptance rule instead of saying only “high tear strength.”
A realistic filled-pack trial
Laboratory tests isolate variables; a filled-pack trial combines product corners, headspace, closure, handling and stacking. Fill the candidate bag with the real product, use the normal closing process and expose it to the most demanding credible part of the route. This practical trial does not replace controlled testing. It verifies whether the selected laboratory indicator actually relates to the application.
Checks to make before increasing thickness
Nominal gauge does not describe every weak point. Uneven thickness, contamination, scratched web guides, hard folds and an undersized bag can concentrate stress. If the part is forced through the opening or moves freely enough to strike the same wall repeatedly, a thicker film may merely delay failure.
Resin and formulation matter, but universal claims such as “this polyethylene is always a fixed percentage stronger” are not dependable. Resin grade, blend, extrusion conditions, gauge and test method all influence the result. Poşetsan compares candidate structures under the same conditions before recommending a formulation change. In a Date Plastik production review, corner protection, fit allowance and film construction are considered together rather than adjusted in isolation.
Write a repeatable acceptance plan
A good specification describes the risk, not just the material name. Define sampling location, conditioning, test method, test direction, number of specimens and the acceptance rule. Do not treat results from two dart arrangements as equivalent. Avoid dividing impact results by thickness to create a simple “per micron” value: impact resistance does not have a universal linear relationship with gauge.
Document the dominant field failure with photographs and retained packs.
Select a laboratory method that represents that failure stage.
Check thickness distribution and both film directions within the lot.
Verify the change in a pilot run using the actual packed product.
Keep the approved sample and test plan for future deliveries.
Information needed for a useful packaging review
Start with product weight, corner shape, bag dimensions, filling method, distribution route and examples of current damage. You can review our PE bags and sacks, see how custom PE bags are produced, or contact Poşetsan Date with a sample. The objective is not the thickest possible plastic packaging. It is a controlled structure that addresses the real damage mechanism and can be verified consistently from one order to the next.