Machine Vision Challenge: Cement Board Inspection

A customer inspecting 4 ft. by 10 ft. white fiber-cement boards required a lighting solution to highlight small 5cm long and 1mm thick surface scratches and defects. They also identified significant surface concavity created during the manufacturing process on some of the 2cm thick boards. As a result, they required the flexible lighting solution to also assist their efforts to develop an identification and grading system to pass/fail board concavity.

The cement boards were inspected in motion, running 1 foot/second through an enclosed tunnel. The inspection setup required a low-angle, narrow beam throw for uniform illumination across the full surface of the board to identify the scratches. The tunnel setup also required the use of longer lights for full board coverage and to facilitate installation.

An additional inspection using the same area-scan camera, but with bright field oriented lighting, necessitated the two lighting orientations be independently controlled with an on/off trigger. The customer contacted Control System Integrators (CSI), Inc. to configure a lighting solution for this inspection challenge.

Ai Solution: High Intensity Bar Lights

Via Ai’s Distribution Partner, Kendall Electric, CSI, Inc. reached out to Advanced illumination to provide a dark field lighting solution for their customer. To match the size and uniformity needs, Ai suggested the LL174 High Intensity Bar Lights with a diffuse light conditioning.

These lights are highly customizable, each available in the 24” length demanded of the application. The configurable control options also allowed for the use of the iCS 3 Inline Cable Controller to enable constant or strobed power to the light. The longer length and controller options met the customer’s initial requirements to fit within the existing machine vision setup constraints.

Illumination Results: Superior Contrast for Inspection

When deployed in the inspection setup, the LL17424-WHII3D Bar Lights provided a uniform light spread across the entire length of the cement board within the inspection tunnel. In comparison to competitive lights tested for consideration in this application, the High Intensity Bar Lights provided superior contrast to identify the scratches and other defects, even with the occasional concave boards.

Board Inspection with Competitive Bar Light

Board Inspection with LL174 High Intensity Bar Light from Ai

According to Daniel Alcala, Vision Automation Engineer for CSI, Inc., “we try to provide our clients with the best possible solution, and the small form factor, high intensity, and high uniformity of the Ai lights made them the best fit for the job.”