Automated Optical Inspection (AOI)

In automated optical inspection (AOI), a machine takes over the task of inspecting components during or after the manufacturing process. Images of the workpiece or assembly to be inspected are taken, which are then analyzed and evaluated with the aid of software. By using automated optical inspection, you get precise results in the shortest possible time.

Find out here exactly how an inspection with AOI works and what the advantages are compared to manual optical inspection.

Optical inspection is a method of testing components within the manufacturing process and evaluating the quality of the finished product. If defects occur in the process, they can be quickly optimized and the defective product can be removed from the production line. In the case of pseudo-defects, the automated optical inspection system learns to tolerate this defect in the future. This saves time and resources.

The inspection process can be performed as a manual optical inspection by the user. In this case, microscopes are usually used as inspection systems. However, there are many machines and systems that can detect defects automatically. In this case, the term automated optical inspection is used. Originally, the term AOI originated in the electrical industry for the inspection of printed circuit boards (PCB). This involved inspecting the solder joints of the PCBs for defects with AOI. In the meantime, however, AOI generally refers to quality assurance based on image processing or machine vision.

Automated optical inspection plays a very important role in quality control and assurance. It not only delivers fast and precise results, saving time and resources. Above all, the results are reproducible and are automatically documented. AOI systems learn very quickly and can be set precisely to the quality control inspection parameters. If the machine classifies a defect, the user can manually look at the faulty workpiece. If the defect was detected correctly, it is a true defect and this information is saved in the AOI system. However, if the user decides that the defect on the part is still within the tolerances, it is a pseudo defect. The machine also learns from this and will no longer identify this defect as an error in the future.

Automated optical inspection is used for quality assurance in these application areas, among others:

• Object identification
• Completeness check
• Presence/absence check
• Defect, pattern and position detection
• 3D inspection
• Component measurement
• Recognition of data matrix and barcodes

The process of AOI has clear advantages over manual optical inspection.

This is because manual optical inspection presents various challenges to the user:

• The human eye can miss defects more easily
• Manual inspection cannot be performed without microscopes due to the very fine structures of the components
• The result of the inspection can differ depending on the condition of the user
• Depending on the user, the result may also differ, because each person judges differently
• Users need to take breaks and can tire quickly due to the work, which requires a high level of concentration

Automated optical inspection provides the optimal solution to these challenges, delivering accurate and reproducible results at high speed.

The benefits of automated optical inspection systems:

• Faster inspection and reproducible results
• High quality results
• Can detect defects early
• Fewer rejects
• Optimization of costs
• Better quality assurance
• Whether a pseudo or real defect is present can still be checked by an expert afterwards