Visual Inspection Method

A. Introduction 

Non-destructiveA careful external visual examination of containers and their seals is the primary means of detecting container defects. 
To visually observe defects in food packages.> 100 ╬╝mOn-line

B. Operation 

Representative samples are obtained from production line. External
surfaces are examined for holes, abrasions, delamination, and correct design. Critical dimensions are measured and observations
recorded.

  • Strong light without glare, for visual inspection of packages
  • Measuring devices, such as ruler, calipers, micrometer 
  • Scissors or knife

Refer to examination procedures for paperboard packages, flexible pouches, plastic packages with heat-sealed lids, and plastic cans with double-seamed metal ends.

Positive

Visually detected defect.

Negative

No visually detected defects.

False positive

Visual identification of defect not actually present.

False negative

Defect is present, but not visually detected.

C. Application 

PACKAGE TYPES AND DEFECTS

 PACKAGE TYPE
DEFECTSFlexible PouchSemi-rigid and
Rigid plastic container
Plastic Can (Double-seam Metal End)Paperboard
Abrasion
Corner Dent   
Crushed  
Cut (Fracture)
Delamination 
Double Seam Defects*   
Flexcracks  
Foreign Matter Inclusion  
Gels  
Hotfold   
Label Foldover   
Leaker   
Leaker (Channel) 
Leaker (Corner)   
Leaker (Notch)   
Leaker (Perforation)   
Leaker (Pulltab)   
Leaker (Seal)   
Loose Flap or Ear   
Malformed  
Puncture (Pinhole)
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)
Waffling   

Visual inspection has a sensitivity of 10-2 Pa m3s, and is generally a gross leak detection technique. This method is time consuming, expensive and its monotonous nature may induce operator fatigue.

D. Source 

ARNDT., G.W. JR. 1998. Chapter 22C Examination of Flexible and Semirigid Food Containers for Integrity. FDA Bacteriological Analytical Manual (8th Ed)