Batches of coiled steel often need to be inspected for compliance with thickness specifications. Conventional measurements are limited to the cut edges at the head of the coil. Ultrasonic thickness measurements, on the other hand, are made from one side only - the exposed side - making it possible to monitor the thickness over the entire width of the coil. Since the thickness can vary as much as 0.002 to 0.004 in. (0.05 to 0.10 mm) from edges to center, steel processors find great advantages in using small ultrasonic gauges.

Equipment: Selection of instrumentation depends on the accuracy that is required. The best accuracy can be achieved with the Model 35DL or Model 38DL PLUS gages with a 20 MHz (M208) or 10 MHz (M202) delay line transducer. In general, the calibrated accuracy with the Model 35DL or Model 38DL PLUS combined with an M116 contact transducer is ±0.001 in. (±0.01 mm). In the High Resolution Mode with an M208 or M202 delay line transducer this gage is capable of approaching a calibrated accuracy of ±0.0003 in. (±0.008 mm) or better if thickness measurements are taken with delay line transducers under optimum circumstances.
Continuous on-line thickness gaging can also be applied to coiled steel, using immersion type transducers. Contact us for details.