Bluewrist
Assembly Line
Automated 3D Inspection System Detects Weld Defects
Since the assembly process involves more than 20 steps, quality control must be comprehensive to ensure that defects are identified at an early stage and reworked. If problems are identified too late in the process, the part must be scrapped.
To guarantee structural integrity, each weld must be inspected. Afterwards, the height of each rivet must be checked with an accuracy of ±0.1 millimeter, since the height of the raised round rivet heads determines how much pressure must be applied when the sheets are joined. Finally, various holes, slots and mounts must be inspected to comply with specifications.
To accomplish these tasks, the carmaker turned to Bluewrist Inc. in Ann Arbor, MI. Bluewrist developed an inline 3D vision inspection system that can continually monitor production quality. Working with the OEM, Bluewrist designed a system that uses two six-axis robots from FANUC and two 3D laser profile cameras from LMI Technologies. As the robots carry out high-speed inspection of all the critical features, the results are recorded and a 3D point cloud is processed and verified against specifications to identify any defects.
The profilers capture detailed surface characteristics of each weld. The weld profile can be inspected in its entirety or broken down into individual sections for analysis and comparison against blueprints to guarantee conformity to length, width, throat thickness, and leg length. The system can inspect fillet, lap, butt, corner, T-joint and plug welds.
Given the complexity of the battery tray, Bluewrist tested the system extensively with feasibility studies before deploying it on the production line. In production, the system performs all the inspections in less than 200 seconds.