Phased array inspection systems have been in use for rapid bar inspection for over 20 years. The bars are transported linearly through a closed ring of curved phased array probes. Coupling is done using local immersion technology. The probes must be matched to the diameter of the bars and must be exchanged in case of major dimensional changes. Nowadays, this inspection concept is very widespread due to the advantages provided by phased array technology, although it comes with a high number of channels and, above all, high probe costs. Depending on the diameter and manufacturer, four to twelve phased array probes are used per dimensional range.
For bar diameters from 20 mm to 130 mm, two probe rings with four to six probes respectively are usually used – i.e. 10 probes in total, requiring more than 700 test channels! The probes each contain between 100 and 128 elements with a pitch between 0.5 mm and 1.2 mm.
Current standards require that the probe is replaced when several adjacent elements have failed. Proper maintenance (incl. cleaning) of the test equipment and the surface condition of the bars (black or bright) have a decisive influence on the service life of the probes.
For some years now, KARL DEUTSCH has been able to manufacture such sensors completely at our headquarters in Wuppertal, and also to supply replacement probes for systems of the common competitors. The radii of curvature range from 35 mm to 235 mm, in special cases even larger. The test frequencies are between 4 MHz and 10 MHz. Common connector types are Hypertronics, I-PEX and Tyco. By now, numerous probes have been delivered to various bar mills local and abroad and have proven themselves in robust industrial use.