C-scan investigation techniques applied to pieces immersed in a tank are used to detect porosity, avoiding the appearance in the subsequent processing steps.

The challenge

The process of metal melting takes place in an induction furnace, using graphite crucibles for their characteristics of resistance to high temperatures.
The liquid from the crucible is poured into special containers called brackets generally in cast iron or graphite, heated to remove the moisture and lightly greased with linseed oil to make it easy to detach the metal from the container.
Once detached, the ingot is subjected to calendering to reduce it into bars ready for the subsequent operations. In this operation  inconveniences may occur that would not make the bar so obtained homogeneous;  the results of the analysis to determine the amount of precious metal content would in that case be affected.

If the bars contain cavities, the defect is serious, since it could emerge in further processing phases (eg the case of a watch, a link in a chain, a buckle, …), threatening the result or even when the product ends up in customer hands.

The solution

The control system is based on immersion of the bar in an acrylic tub filled with liquid (water).
The probe to perform ultrasonic control is operated by a motor with electronic motion control on axes X and Y, while  Z axis is set manually. The software combines movement and control  with the acquisition of data to provide the  ultrasound imaging.

The system provides maximum flexibility in the definition of the operating parameters, based on length and thickness of the bar and on the sampling points desired.

Project Details

TAGSUltrasound, C-scan in the tank