Precision 3D Inspection of EV Battery Sealing Nail Welds

Overview

Crisp point clouds provided by two Sizector 3D cameras empower battery manufacturing and quality control.

As the power source for New Energy Vehicles (NEVs), the safety and stability of power lithium batteries are critical to user experience and passenger safety. Consequently, defect detection efficiency at key structural points determines both the production throughput of battery manufacturers and the service life of the battery itself.

This case study demonstrates the application of the Sizector^® 3D Camera in the critical inspection of sealing nail weld seam on prismatic cell injection ports.

Application Background

To ensure the airtight sealing of EV batteries, the manufacturing process involves injecting electrolyte into the battery module through an injection hole. A sealing nail (cap) is then installed, and laser welding is used to seal the gap between the nail and the lithium battery shell.

Due to the nature of raw materials and the production environment, this process is susceptible to contamination. During welding, environmental pollutants or process instabilities can lead to surface defects such as pores, spatter, and blowholes, which compromise the battery's integrity.

Common defects in a sealing nail weld

Expectations & Challenges

Weld inspection is a critical quality control step, yet traditional visual inspection solutions often suffer from high rates of false negatives (missed defects) and false positives (wrongly rejected parts). Manufacturers require a 3D vision solution that can:

• Efficiently distinguish whether the weld has blowouts, missing welds, namely skips, or burn-throughs.

• Prevent electrolyte leakage which leads to severe quality and safety issues.

The Technical Challenge

• High Reflectivity: The weld material is highly reflective metal, which causes noise and interference for standard cameras.

• Micro-Defects: The defects are often extremely small and difficult to distinguish with the naked eye.

Imaging Results

By utilizing the Sizector^® 3D Camera, we achieved a high-quality 3D point cloud that clearly captures defects in the sealing nail weld.

The system successfully identified a pinhole-shaped burn-through defect (as shown below), which would have been easily missed by 2D imaging.

Caption: Amplified view of weld defect captured by Sizector^® 16.2 MP 3D Camera (Standard 3D Mode, Dual Exposure).

Summary

The Sizector^® 16.2 MP 3D Camera excels in solving planar inspection and measurement challenges that previous generations of products could not handle effectively.

By leveraging high-resolution 3D imaging, vision system users can transition from complex "2D + 3D" camera combinations to a one-stop fusion inspection solution. This integration simplifies the algorithm, accelerates the detection cycle time (takt time), and significantly improves the quality and efficiency of the production line.