The Schneider Electric/Square D Lexington plant has been assembling residential load centers and safety switches since Dwight D. Eisenhower was president of the United States. But, a wide variety of state-of-the-art production tools are used today to assemble world-class products.

One technology that did not exist when the 2007 Assembly Plant of the Year opened 50 years ago is machine vision. The plant has undergone a major push in recent years to standardize and upgrade the controls that provide its quality-oriented vision inspection stations on its assembly lines. For example, multiple camera vision inspection stations were upgraded from outdated Apple Mac-based control systems to PC-based systems.

“They allow for common vision configurations to be shared across multiple assembly lines,” says Bruce Molinar, senior manufacturing engineering manager. “The more powerful PC systems also provide additional quality checks that the older systems were not capable of, such as optical character recognition to identify alphanumerically marked components.”

The plant uses vision technology to validate if critical components are present and prevent outgoing quality defects from reaching the customer. “We review our product returns and customer feedback data once a month, or as needed, to determine the root cause for quality errors,” explains Molinar.

A variety of vision systems are used on the assembly line to confirm product integrity. For instance, they accurately confirm the correct part and part placement in each assembly. Closed-loop systems prevent suspect material from entering the packaging area, allowing operators the opportunity to correct the defect prior to packaging.

For example, on one of the load center cover assembly lines, a camera shows an operator if a bag of screws is present beneath the cover. The bag is placed in the cover by an automated bagger. However, because the cover is flipped over by a robot prior to final packing, the operator can’t see if the bag is present.

Vision systems are also used to verify the presence of a spring and a door label, and to inspect cut-outs for breakers. Any errors are automatically rejected.

In addition, vision technology is used to confirm electrical continuity in support of the plant’s ISO 9001 certification. A millivolt test prevents customers from receiving a product that may not be suitable for its intended application.