Thermal paper coating process inspection
Thermal paper coating process inspection record form
Thermal paper coating process inspection record form
Applicable processes : Primer, thermal color developer, topcoat/protective layer – full coating process.
Inspection frequency : Initial inspection upon machine startup, inspection every 30 minutes, mandatory inspection after roll change/machine adjustment.
Applicable products : Ordinary thermal paper, three-proof thermal paper, POS/label thermal master rolls.
Basic production information
date: Shift: Morning/Midday/Evening
Machine Number: Operator: Patrol Inspector: Work order number:
Product Specifications: Production in meters:
Coating structure: Primer □ Color-developing coating Topcoat
I. Production Environment Inspection (Required)
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Inspection items |
Standard requirements |
measured data |
Determine OK/NG |
Remark |
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Workshop temperature |
22–28℃ |
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Workshop humidity |
40%–60% (>60% may result in uneven coating or whitening) |
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Environmental cleanliness |
No floating dust, no debris, and no scale buildup on the roller surface. |
Visual inspection |
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II. Inspection of Equipment Process Parameters (Core Quality Control)
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Inspection items |
process standards |
Measured value |
determination |
Exception Log |
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production line speed |
Set the speed to ±5m/min according to the work order. |
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Coating roller gap |
Standard clearance for weight, no left or right deviation |
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Coating working pressure |
Stable pressure with no fluctuations and no bias. |
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Unwinding/Rewinding Tension |
The winding tension is 20%–30% lower than the unwinding tension, and there is no edge slippage. |
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Oven Sectional Temperature |
Inlet/Middle/Outlet temperatures are as per process card; no overheating. |
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Drying moisture content |
The finished product has a moisture content of 8%–11%. |
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III. Inspecting Coating Liquid Parameters (Preventing Whitening, Exposed Base Material, and Powdering)
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Inspection items |
standard |
Actual measurement |
determination |
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Coating solids content |
Process standard ±1% |
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Coating viscosity |
Standard viscosity range, no agglomeration |
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Stirring state |
Continuous stirring, no sedimentation or stratification |
Visual inspection |
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Coating cleanliness |
No impurities, no colloids, no skin. |
Visual inspection |
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IV. Coating Appearance Quality Inspection (High-Frequency Defect Inspection)
Sampling method: Samples are taken from the beginning, middle and end of each roll.
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Appearance defects |
Qualification Standard |
Does it exist (no/yes)? |
Disposal |
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Coating uniformity |
Consistent color difference between left and right sides, no uneven coloring. |
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Stripes/Brushed |
No transverse or longitudinal coating stripes |
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Pinholes/White Spots |
The entire surface is free of dense pinholes and white spots. |
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Particulate impurities |
There are no raised particles or pinholes when touched. |
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Slip-on/Thin-on coating |
No exposed base layer, thin local coating |
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Wrinkles/Scratches |
The paper surface is flat, without creases or wrinkles. |
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End face alignment |
End face misalignment ≤2mm |
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V. Key physical property testing (mandatory testing specifically for thermal paper)
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Testing items |
industry standards |
Test results |
determination |
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Dry film coating thickness |
Total coating thickness: 5–8 μm, with a deviation of ±1 μm |
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Colorimetric sensitivity |
The printing produces uniform blackness, fast color development, and no light prints. |
Test Print |
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Base whiteness |
The base color is clean and free of yellowing or graying. |
Visual comparison of samples |
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Coating adhesion |
No powder or delamination when the tape is peeled off. |
Tape test |
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VI. Recording and Handling of Anomalies During Initial Inspection/Patrol Inspection
- The main abnormalities identified during this inspection were:
- Abnormal Handling Procedures: Shutdown for Adjustment □ Fine-tuning Parameters □ Isolate for Inspection □ Normal Production □
- Re-inspection results: Pass □ Fail □
VII. Signature Confirmation
Operator confirmation: Inspector confirms: Team leader confirms: Inspection time:
Simplified SOP for workshop inspection
- First inspection must be performed before starting the machine, changing the roll, adjusting the machine, and changing the coating ; mass production can only begin if the inspection is passed.
- Test every 30 minutes: temperature, humidity, thickness, and color development effect;
- If stripes, uneven thickness, or poor color appear , stop the machine immediately and adjust it . Mass production with defects is prohibited.
- When humidity exceeds 60%, strictly control the coating speed to prevent the coating from absorbing moisture and turning white, and to prevent poor adhesion.
- Excessive winding tension is strictly prohibited to avoid coating back adhesion and printing failure.
- 2026-08-19
- 2026-08-13
- 2026-07-07
- 2026-06-28
- 2026-06-21
