Our Large Gantry On-line Automatic Hardness Tester is designed as a "quality inspection gate" for modern heavy industrial production lines. It breaks through the size limitations of traditional laboratory testing, featuring a robust gantry structure with a maximum testing width of up to 3 meters. Remarkably, it achieves laboratory-equivalent precision while performing tests in under 5 seconds per point, making it fully capable of keeping pace with the continuous operation of steel hot rolling, aluminum extrusion, or large forging production lines. The system’s core value lies in its realization of true automation and closed-loop operation. By seamlessly integrating with the production line PLC system, hardness data is uploaded in real-time to the production management system. In the event of detecting non-conforming products, the system automatically triggers sorting mechanisms to remove them. This "detection and sorting" model not only eliminates the costs associated with manual intervention but also effectively prevents substandard products from moving on to subsequent processes.