A new vision system integrated into the inspection process at a car battery manufacturing plant improved the error detection rate to 99% and saved the manufacturer both money and labor.
Car batteries are made up of six books with two cells per book. Orange paint is applied to the battery book to indicate polarity. The orange alternates with white to ensure proper alignment and therefore proper performance of the battery. The manufacturer was using a photo eye that inspected each cell for a specific shade of orange in the location where color was expected.
The color was well defined before the battery was molded with hot lead, but a new process caused the orange to diminish, and burned cells turned the orange to brown. Inspection instruments were no longer picking up on cell alignment due to a change in the color. As a result, operators were spray-painting cells to reapply the orange. Besides being inefficient and messy, the manual intervention could lead to human error.
Further complicating the process, battery books sometimes were pulled from different lines where the photo eye was trained to identify a different shade of orange. Another problem was overspray of the orange paint. Customers seeing orange paint on the exterior of the batteries mistakenly perceived the batteries as seconds.
