Prepared by:
Guanjie (Jason) Wang |
Technical Solutions Lead
Operating entity:
Dongguan Chenghua Industrial Co., Ltd.
Manufacturing profile:
Company-reported combined manufacturing area of approximately 40,000 m² across three production bases
Document status:
Public buyer guide; not a controlled product specification or shipment certificate
Last reviewed:
July 28, 2026
I. Purpose of This Guide
This guide helps B2B buyers define inspection requirements for custom polyethylene bags and film. It does not establish one universal Flexon Pack standard for every product.
Material, dimensions, tolerances, test methods, sampling frequency and acceptance limits must be agreed in the approved quotation, product specification, artwork and quality agreement before production.
A target shown as an example in this guide is not automatically included in an order. The final saleable specification is determined only by the documents approved for that project.
II. Products Covered by Project-Level Review
The inspection framework may be adapted to eligible custom products, including:
- Press-to-close ziplock bags
- Slider zipper bags
- Self-adhesive PE bags
- Flat open-top PE bags and liners
- PE film, tubing, sheeting and rollstock
- Printed and unprinted custom constructions
Security, food-contact, laboratory, anti-static, recycled-content and other controlled applications require a separate specification and evidence review. A general PE-bag inspection plan does not establish suitability for these uses.
III. Information Required Before Inspection Criteria Are Set
- Product type and finished construction
- Finished width, length, gusset, flap and usable internal dimensions
- Nominal single-layer thickness and requested tolerance
- LDPE, LLDPE, HDPE, blend or recycled-content requirement
- Film color, additives and required appearance
- Printing method, colors, coverage, artwork and barcode requirements
- Zipper, slider, adhesive, venting, perforation or other components
- Packed product, unit weight, sharp-edge risk and packing method
- Intended use, storage conditions and destination market
- Required declarations, test reports and shipment records
IV. Recommended Inspection Categories
1. Material Identification
The approved specification should identify the required polyethylene type or blend and whether virgin or recycled content is permitted. Visual appearance alone cannot prove the resin grade, recycled-content percentage, presence of fillers or regulatory status.
Depending on the project, material evidence may include a supplier declaration, resin identification, incoming-material record, batch reference or an agreed laboratory test. The required record and its link to the finished order must be defined before production.
Virgin PE is not automatically suitable for every application, and recycled PE is not automatically defective or non-compliant. Each formulation must be evaluated against the intended performance and documentation requirements.
2. Visual Appearance
Visual acceptance criteria may address:
- Holes, tears, gels, black spots or visible contamination
- Wrinkles, blocking, distortion or uneven sealing
- Zipper or slider alignment
- Adhesive-strip position and release-liner condition
- Print defects, smearing, missing content or incorrect artwork
- Unusual odor when odor is a defined acceptance characteristic
Terms such as “odorless,” “zero contamination” or “surgical grade” should not be used without a defined method and acceptance limit.
3. Dimensions and Film Thickness
Dimensions and thickness should be measured using agreed definitions. Buyers must specify whether width and length are internal or external and whether thickness refers to one film layer or the combined thickness of two layers.
A target thickness tolerance such as ±5% may be reviewed for eligible specifications when technically feasible and expressly confirmed in the approved quotation. It is not a universal tolerance across all Flexon Pack products.
The inspection plan should record:
- Nominal dimension or thickness
- Permitted upper and lower limits
- Measurement equipment and resolution
- Measurement-point locations
- Number of samples and sampling frequency
- Rule for accepting or rejecting the inspected lot
No general industry tolerance should be quoted without a published source and comparable product definition.
4. Printing
Printing requirements should be tied to the approved artwork and production method. Appropriate criteria may include:
- Correct artwork version and orientation
- Spot-color or process-color reference
- Print position and permitted registration tolerance
- Barcode content and readability where applicable
- Ink adhesion using an agreed test method
- Smearing, blocking and set-off criteria
Values such as registration tolerance, color difference or adhesion performance must be agreed for the project. They should not be presented as universal production results without supporting records.
5. Seal and Closure Performance
Seal, zipper, slider and adhesive performance depends on the material, thickness, construction, packed product and conditions of use. Possible inspection items include:
- Bottom-seal or side-seal continuity
- Zipper engagement and alignment
- Slider retention and end-stop condition
- Adhesive-strip position, opening behavior and residue
- Leakage, peel, burst or tensile testing where relevant
- Functional packing trial using a representative packed item
The required test method, conditioning, speed, sample dimensions and acceptance value must be stated. A percentage of base-film strength or a universal “zero failure” requirement should not be assumed.
6. Mechanical Performance
Tensile strength, elongation, tear resistance, dart impact and puncture resistance are material- and construction-dependent. They cannot be inferred solely from a supplier name, resin brand or nominal thickness.
Where these properties are important, the buyer should identify the test method, sample orientation, conditioning, required value and applicable laboratory or production test. Results for one resin or film construction must not be extended to a different construction without review.
7. Self-Adhesive Bag Stability
Adhesive performance can be affected by adhesive type, film treatment, storage duration, temperature, humidity, dust, packed-product surface and repeated opening.
Shelf life should not be stated as 12 or 18 months unless it is supported by the selected adhesive system, storage conditions and an agreed evidence method. A short accelerated-aging exposure must not automatically be treated as proof of a specific real-time shelf life without a validated correlation.
Buyers requiring shelf-life evidence should define:
- Adhesive and release-liner construction
- Storage temperature and humidity range
- Expected storage duration
- Opening, peel, tack and residue requirements
- Real-time or accelerated-aging method and its limitations
8. Tamper-Evident and Security Constructions
A standard PE bag is not automatically tamper-evident. Security bags require a separately approved construction and test plan.
Where tamper evidence is required, buyers should define the intended attack conditions, visual indication, temperature range, chemical exposure, closure method and acceptance criteria. Testing should be conducted on the approved finished construction.
V. Compliance and Document Review
Quality inspection and regulatory evidence are related but separate. A bag can meet dimensions and appearance requirements while lacking the documents needed for a particular market or application.
1. Food-Contact Evidence
A resin declaration or report referring to FDA 21 CFR 177.1520 does not automatically certify every finished bag. Buyers should confirm the exact resin, additives, colorants, inks, zipper, adhesive, intended food type, temperature and contact duration.
The evidence may cover a raw material, representative sample or named finished bag. Its scope must be checked before it is applied to an order.
2. PFAS Evidence
A declaration that specified PFAS substances are not intentionally added is not equivalent to a laboratory result showing no detected PFAS above defined reporting limits.
If analytical testing is required, the parties should agree on the tested sample, target substances, test method, reporting limits, laboratory and relationship between the report and production order.
3. REACH, RoHS, PPWR and Other Requirements
These requirements have different scopes and must not be merged into a general “global compliance” claim. Ordinary packaging is not automatically within the legal scope of every restricted-substance regime.
Buyers should identify the applicable destination, product use and evidence requirement. A report for selected substances does not establish complete compliance with an entire regulation.
4. Recyclability and Recycled Content
A predominantly PE construction may support a recyclability assessment, but it is not automatically recyclable in every market. The complete structure—including zipper, slider, adhesive, ink, label, coating and additives—must be considered.
Recycled-content claims should identify the percentage, material source, calculation basis and applicable chain-of-custody evidence.
VI. Sampling and Inspection Frequency
Inspection frequency should be selected according to product risk, order size, process capability, previous performance and buyer requirements. Flexon Pack does not apply one publicly stated AQL level or inspection interval to every order.
The approved quality plan may identify:
- Incoming-material checks
- First-article or start-up approval
- In-process measurement frequency
- Final lot-sampling method
- Critical, major and minor defect classifications
- Acceptance and rejection numbers
- Retest and corrective-action procedure
If an AQL plan is requested, the inspection standard, lot size, inspection level and acceptance limits should be stated in the approved order documents.
VII. Measurement and Test Equipment
Equipment should be selected according to the agreed characteristic and test method. Possible tools include micrometers, dimensional gauges, weighing equipment, tensile testers, seal-strength equipment, leak-test equipment and environmental-conditioning equipment.
The existence of a particular instrument should be confirmed for the applicable manufacturing or laboratory site. Calibration status, resolution and test capability should be verified when they are relevant to buyer approval.
Chemical analysis such as chromatography or mass spectrometry may require an external laboratory. Any third-party report should identify the laboratory, method, sample, reporting limits and test date.
VIII. Available Production and Shipment Records
The documentation supplied with an order depends on the approved specification and contract. Buyers should not assume that every shipment automatically includes a complete digital quality dossier.
Records that may be requested and confirmed before ordering include:
- Approved product specification
- Approved artwork or print reference
- Purchase-order and internal product reference
- Production date or batch reference
- Material identification record where applicable
- In-process or final inspection report
- Certificate of Conformity or Analysis when specifically agreed
- Applicable third-party test report
- Packing list and shipment documentation
A raw-material COA, supplier declaration, finished-product inspection report and third-party laboratory report serve different purposes and should not be treated as interchangeable.
IX. Non-Conforming Product and Corrective Action
A non-conforming result should be evaluated against the approved specification and sampling plan. One failed sample does not automatically define the disposition of an entire production lot unless the agreed acceptance rule states that it does.
Depending on the issue and agreed quality terms, possible actions may include:
- Confirming the measurement method
- Increasing the sample size
- Segregating the affected material
- Reworking or replacing affected goods where feasible
- Investigating the root cause
- Recording corrective and preventive actions
- Reinspecting before release
X. Buyer Acceptance Checklist
- Is the legal manufacturer identified?
- Is the product specification dated and version-controlled?
- Are material and component requirements unambiguous?
- Are dimensions and thickness defined using the same measurement convention?
- Are test methods and acceptance limits stated?
- Is the sampling plan appropriate to the order risk?
- Does each compliance document match the proposed material or finished construction?
- Are required production and shipment records listed in the order?
- Has a representative sample or pilot run been approved where necessary?
- Is the non-conforming-product process agreed?
Evidence Boundary
This page is an educational inspection framework. It is not a product certificate, controlled factory procedure, universal inspection standard, regulatory declaration or guarantee of product performance.
Flexon Pack’s published width, thickness, printing and manufacturing ranges describe general capability only. Actual capability, tolerance, inspection frequency, test evidence and documentation must be confirmed for the exact product and current production order.
The approved quotation, product specification, artwork, sample, quality agreement and applicable supporting documents define the final saleable product.
Contact Flexon Pack with the product dimensions, single-layer thickness, material, packed item, order quantity, printing, destination and required inspection documents to request a project-specific review.
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