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Advantages of 3D Over 2D Methods for Sealant & Adhesive Bead Inspection

There are many reasons why customers choose Coherix 3D machine vision solutions over traditional 2D solutions. Volume is a 3D metric which requires a 3D inspection solution and 2D cameras cannot even pick up the volume information by the essence of how they operate. The dispensing equipment can only provide total volume dispensed, it cannot tell how much volume is applied at what location. Dispensing the specified volume in the specified location is critical to ensuring structural rigidity.

Coherix 3D Inspection System

  • Exceptionally robust inspection
  • No penalty to cycle time
  • Low maintenance
  • Full 3D representation of 3D parts – provides true volumetric height information
  • Sensors are impervious to ambient lighting
  • Sensors are impervious to part color changes, especially in “black on black” or “gray on gray” situations
  • Fewer false failures
  • Allows user to inspect volume & location where glue bead is dispensed
  • 100% reliable
  • Ideal for sharp-turning adhesive or sealant bead path dispensing because the use of 4 lasers
  • Perfect for high-profile urethane beads typically used on glass windows
  • Inspects a 3D surface map of an assembly
  • Easy to set-up because sensor head is a monolithic unit with no components to misalign, as long as the sensor head is positioned at its nominal standoff & is pointing at the part, it will inspect parts reliably
Learn More About 3D Machine Vision Products

Traditional 2D Inspection System

  • Marginal inspection
  • Penalty to cycle time
  • High maintenance
  • Only provides 2D information for 3D parts – doesn’t provide information on true volumetric height
  • Ambient lighting effects results
  • Cameras can’t detect differences between same color adhesive and surface
  • Temperamental
  • Allows user to inspect location, but not volume of bead which could be the cause of squeeze-outs & structural rigidity concerns
  • Unreliable
  • Cameras cannot stay in the correct position on sharp turning bead paths
  • Run into numerous issues with high-profile urethane beads typically used on glass
  • Does not inspect an assembly, inspects 2D image of an assembly
  • Difficult to set-up because even small variations in the location of components with respect to each other can result in an unreliable inspection because it relies on precise spatial relationship between the part, lighting & camera
  • Limited in that it can only extract data from parts of the image where there is contrast between pixels

Z-Axis Blog: Advantages of 3D Vision for Adhesive and Sealant Dispensing

Over the years the industry has tried hard to utilize 2D vision for the dispensing process, but this endeavor has not been very successful for many reasons:

2D cameras are typically implemented as a post-process, meaning dispensing first and then the 2D check afterwards. That adds significant cycle time, which most automotive manufacturers don’t have the luxury of. The 2D inspection station requires separate floor space, which is also very valuable in any manufacturing plant

Most dispensing applications in automotive involve free-form parts with complex geometry.  For this scenario, the 2D post and static inspection cannot even get to most sections of the bead unless it is carried by the robot for the cameras to pick up, which will add even more cycle time…Continue reading Dr. Zhenhua Huang’s Z-Axis Blog here

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