Guide du débutant sur les défauts de qualité courants dans les processus d’emballage flexible
Flexible packaging production involves multiple steps—printing, lamination, bag-making, et plus. A failure in any link can lead to scrapped finished goods. For newcomers, systematically understanding the typical quality defects in each process—and their root causes—is essential for getting up to speed quickly. This guide covers four areas: raw materials, impression, lamination, and finished-package inspection.
1. Raw Material Film Defects
Appearance issues: gels (crystal spots/ fish eyes), streaks, scratches, holes, oil stains, foreign matter, insufficient surface tension (which directly affects print adhesion and lamination strength), uneven thickness, and deformed core rolls.
Physical property failures: low tensile strength, excessive or uneven heat shrinkage, coefficient of friction outside the process window, and barrier properties (oxygen/water vapour transmission rate) failing to meet specifications.
2. Printing Process Defects
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Colour deviation: inconsistent ink batches, fluctuating printing pressure, or different substrate background colours.
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Doctor-blade streaks / dirty plates: worn doctor blades or impurities in the ink.
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Poor adhesion: inadequate or degraded corona treatment on the substrate, or an ink formulation incompatible with the film.
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Excessive solvent residue: insufficient drying temperature or unbalanced solvent evaporation rates.
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Misregistration: improper tension control or inadequate machine precision.
Key control principle: From material selection, machine setup, and online monitoring to data-driven management, focus on the three links—“precise parameter setting → real‑time status monitoring → closed‑loop data feedback”—to ensure stable and efficient printing.
3. Lamination Process Defects
Low peel strength (délaminage):
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Adhesive factors: wrong mixing ratio, poor mixing, exceeding pot life, insufficient or uneven coating weight, poor adhesive quality, or incomplete curing (under‑curing).
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Substrate factors: low surface tension (corona degradation), or contamination by oil, dust, or migrating additives.
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Process factors: clogged or worn anilox/coating rollers, improper drying temperature/airflow (causing solvent retention or surface skinning), insufficient lamination temperature/pressure, or improper winding tension (too high or too low).
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Curing factors: inadequate curing temperature or time.
Bubbles / white spots (visible air pockets or un-bonded areas between layers):
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Uneven adhesive coating (clogged anilox roller, unsuitable viscosity, or uneven coating pressure);
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Contaminated substrate surface (huile, dust, humidité);
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Low lamination pressure or roller temperature;
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Insufficient drying, causing residual solvent to vaporise after lamination;
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High ambient humidity causing adhesive to absorb moisture;
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Rough film surface or presence of gels.
Uneven adhesive distribution / missing adhesive: coating weight fluctuates in the transverse or machine direction, or local areas receive no adhesive.
Heat‑seal layer contamination: adhesive or solvent splashes onto the inner heat‑seal layer during lamination, causing poor sealing in subsequent bag‑making.
Excessive solvent residue: solvents in the adhesive are not fully evaporated.
Wrinkles: creases or folds appearing on the laminated film surface.
4. Finished‑Package Quality Defects
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Missed detection: failing to identify and reject non‑conforming products that contain any of the above defects.
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Incorrect count: under‑filled or over‑filled boxes/packs.
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Label errors: wrong or missing information (product name, specification, quantity, batch number, date, etc.).
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Damaged / contaminated outer packaging: broken or dirty cartons that compromise the inner products.
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Batch / specification mixing: different batches or different specifications packed together.
5. Systematic Prevention and Control
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Strict incoming material inspection—quality starts with the raw film.
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Standardised and fine‑tuned process control—all parameters, monitoring, and records must be traceable.
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Preventive equipment maintenance—pay special attention to rollers, doctor blades, anilox rolls, heat‑seal knives, and other critical components.
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Well‑defined operating procedures and staff training—empower operators to identify defects and respond to abnormalities promptly.
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Dual‑layer quality assurance: in‑line inspection + final product inspection—ensure that non‑conforming products never reach the customer.
