Non-destructiveTo detect defects in hermetic packages by computer evaluation of infrared (IR) ages with previously defined patterns of acceptance.> 50 μm channel, > 100 μm pinholesOn-line, > 5 s> $50,000
Infrared light may be absorbed, transmitted, and emitted by a package or a seal. Differences between these parameters provide a means for visual interpretation when sensed automatically and enhanced for visibility.
Infrared imaging (IRI) thermography is an inspection technology that can be implemented on-line in industrial quality control systems to enhance efficiency in removing defective packages. According to the industry, the IRI technique makes a merit of non-destructively scanning and thermally imaging surfaces of various materials.
- Sample packages
- Infrared camera
- Seal packages by using heat sealers.
- Take thermal images after heat sealing by using an IR camera at heat-sealing temperatures in the range of 60 to 140oC. Thermal information in the 3 to 5 μm infrared band will be measured and recorded.
- Analyze images at IR Iron, Midgreen, or Midgrey image palette modes.
- Infrared images of packages with different standard defects are shown in Figures 1 and 2. Each image was taken at an interval of 1/30s and a shutter speed of 2 μs. In general, all defects were easily identified and further characterized by the infrared imaging (IRI) technique. Limit of detections (LODs) of the IRI technique for microchannels in foil-laminate packages and plastic packages were 180 μm and 40 μm, respectively. The LODs for pinholes in in foil-laminate packages and plastic packages were 100 μm and 160 μm, respectively.
- Linear regression analysis of seal quality data in Figure 3 indicated that average initial surface temperatures of heat-sealed area obtained from infrared images were significantly correlated with seal strength.
PACKAGE TYPES AND DEFECTS
|DEFECTS||Flexible Pouch||Semi-rigid and Rigid plastic container||Plastic Can (Double-seam Metal End)||Paperboard|
|Double Seam Defects*|
|Foreign Matter Inclusion|
|Loose Flap or Ear|
|Seal Defects (Blister)|
|Seal Defects (Blocked)|
|Seal Defects (Burnt)|
|Seal Defects (Compressed)|
|Seal Defects (Contaminated)|
|Seal Defects (Convolution/Embossing)|
|Seal Defects (Creep)|
|Seal Defects (Crooked)|
|Seal Defects (Incomplete)|
|Seal Defects (Misaligned/Deformed)|
|Seal Defects (Nonbonding/Weak)|
|Seal Defects (Plastic Lumps)|
|Seal Defects (Seal-width Variation)|
|Seal Defects (Stringy)|
|Seal Defects (Uneven Impression)|
|Seal Defects (Uneven Juncture)|
|Seal Defects (Wrinkle)|
|Swell (Swollen Package)|
The application is limited by the need for statistical chracterization of all defects and subsequent computerizations.