TECH TIPS: Automated vision inspection of welds in automotive line assembly

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Inspecting weld seams on an automotive battery frame using automated vision inspection. (PHOTO courtesy VITRONIC Machine Vision)

By Wayne Pugh

Automotive component manufacturers face a number of production challenges. Among the most vital is maintaining a high level of product quality, supported by consistent production throughput with systems that ensure profitability. A key function in this process is assembly,especially as the demand for more automated sensing and control devices, connectivity, infotainment, and electric vehicle components like battery trays, continue to push the need for more complex assembly requirements.

The need to manufacture more complex assemblies poses challenges for process engineers in their manufacturing and assembly functions. Particularly so, as automotive component manufacturers are increasingly mandated by stricter requirements to document quality assurance of their manufactured products along each step of production.

The growing demand for alternative, energy-saving, low-emission drive technologies requires a radical rethink on the part of the automotive industry. Short development cycles, safety issues, innovative manufacturing and assembly processes, and new production lines mean constant challenges. This significantly raises the need for more efficient manufacturing processes and quality inspection.

Weld-Seam Safety

A critical component supporting vehicle safety in automotive manufacturing is maintaining integrity in weld seams. Today’s cutting-edge technology uses automatic welding for assembling vehicle body frames, axle components, powertrain systems, passenger seats, steering wheels, electric vehicle battery trays, and dozens of other components.

Defective weld seams, especially in safety-relevant automotive components, can lead to serious problems for manufacturers. The need to rework mis-welded components, interrupted production lines, and in worst-case scenarios product recalls and liability claims, can cause manufacturers significant costs. Consequently, inspecting welds for defects becomes a critically import function in automotive component assembly.

Latest Evolution of Automated Weld-Seam Inspection

Manual inspection of welds in automotive assembly is prone to errors and costly to perform. Production efficiency can be increased considerably when the inspection of weld seams is fully automated. Automated weld seam inspection has been successfully used since the mid-1980s in the international automotive and automotive supply industries, including all Tier-1 suppliers and integrators. 

The continual evolution of automated inspection technology, combined with advances in robotic assembly and computing capability, have enabled the latest generation of inspection systems to perform with extremely high reliably. Every weld seam is automatically inspected and documented after each manufacturing step to minimize serial defect trends and ensure product quality traceability.

Integrated Inline Inspection

The latest evolution of automated weld-seam inspection technology consists of an inspection cell with a sensor that is installed directly in the welding station at various locations. Because the inspection takes place in the welding line directly, it is easy to quickly intervene in the upstream welding process should a component require rework. As a result, defects are consistently identified and reduced, processes are optimized, and down time, reworking and waste are avoided.

This latest inspection technology does not require a dedicated station or dedicated robot. The inspection system can be easily retrofitted to existing lines, regardless of the welding solution used. Supporting the inspection cell-sensor is high-performance computer processing capability equipped with software for trending and analytics.

The latest evolution in weld seam inspection, from VITRONIC, inspects weld seams for an automotive manufacturer. (PHOTO courtesy VITRONIC Machine Vision)

Expanded Inspection Range

Unique to this new generation of automated weld inspection is an exceptionally broad sensing range. The inspection criteria can be configured to suit diverse requirements and applications.

The system is extremely reliable, even when it encounters flat seams, highly reflective materials such as aluminum, seams with differing geometries, and fast image recording speeds.

This expanded range of inspection includes the following parameters:

  • Throat thickness
  • Distance in X, Y
  • Undercuts
  • Hole/burn-through
  • Weld connection signal jumps
  • Seam connection angle
  • Seam width/length
  • Seam width/position for overlap seams
  • Seam position
  • Convexity or incompletely filled groove
  • Seam irregularity
  • Weld volume
  • Butt weld
  • Surface irregularity
  • Object height
  • Porosity
  • Spatter
  • Gap width for overlap seams
  • Unequal leg length
  • Deepening

The automated weld inspection is capable of pinpointing the exact size and position of each defect and classifying them. It clearly identifies the tiniest geometric and cosmetic deviations.

Simplified Reworking

All information relating to the weld seam inspection is visualized in the software of this latest-evolution weld-seam inspection system. From setting parameters for inspection to the display of defects for reworking. Clear visualization of defects in live operation are displayed as:

a) Real images

b) Precise, detailed inspection images

c) 3D visualization

Defects can be easily analyzed and reworked because of the various visualizations. The software provides detailed instructions for reworking.

The displays are extremely precise, clear and understandable. Operators can independently access results and rework defects using an integrated touch display, or through external visualization stations. In addition to purely manual reworking, a special classifier also supports automated reworking.

Vehicle Body Weld-Seam Inspection

Weld-seam detection presents a particular challenge with flat vehicle body seams. Even the slightest defect can affect the integrity and salability of the vehicle.  All welding defects in the vehicle body – on both visible and invisible seams – need to be detected immediately after the welding process and corrective actions swiftly implemented. The latest evolution of automated weld-seam inspection is ideally suited to ensure only perfectly welded vehicle bodies leave the production line.

Weld Seam Inspection for Axle Components

Axle beams and transverse control arms are essential elements of a safe chassis subframe. Their quality is critical to the long-term safety of vehicle occupants. The most advanced automated weld-seam inspection should be employed to identify defects and get them corrected before the axle components reach further processing stages.

An automated weld-seam inspection system like VIRO WSI combined with process optimization software, supports manufacturers in delivering automotive components of consistent high quality, while having a direct impact on better managing production volumes and costs.


Wayne Pugh is Vice President, Automation North America VITRONIC Machine Vision Ltd. USA. For more information contact VITRONIC Machine Vision Ltd. USA,

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