FEATURE Machine Vision
include up to 50 independent layers. The resolution of the microscopic image depends on the acoustic frequency, material properties and aperture of the transducer. Transducers perform such a critical role that manufacturers like PVA TePla design and manufacture an extensive range of diff erent transducers used in their contracted testing services. The frequency of the ultrasonic signals can be increased to the GHz range, allowing it to detect defects in the sub- micron range. At PVA, their contract testing services
are performed only on equipment the company manufactures, namely the 300, 302 HD2, 500 and 501 HD2 scanners, with scanning ranges of 200μm x 200μm to 500mm x 500mm using transducers of up to 400MHz.
Given the critical role it plays, in-depth knowledge of the advanced software features available is another considerable benefi t.
“SAM testing houses that purchase equipment may only be familiar with some of the features of the software,” said Logan. “As the manufacturer, we have to understand all the features and can even request customisations if needed.”
Correct interpretation The quality of the equipment and knowledge of its use are key factors in SAM testing, but operating a SAM system requires a trained technician and, even more importantly, experience confi guring the equipment and interpreting the scans.
PVA TePla SAM 502 HD2
system
Setting up the scans and interpreting the images is similar to a radiologist reading medical MRI scans. “Wouldn’t you want your doctor to have the clearest image possible to make the best medical decision,” asked Logan. “When you realise that an undetected fl aw can have a catastrophic impact on a part, it’s the same for quality testing too.” SAM system experts work with three
diff erent imaging modes, A, B and C. Mode A is an X, Y or Z point, and provides information on all the echoes occurring inside a part, providing insight into the material, time-of-fl ight, amplitude and polarity. This scan must
be interpreted appropriately to produce an accurate B or C scan that is shared with the customer.
PVA TePla SAM capabilities provide superior testing to manufacturers looking to outsource
“An operator needs to interpret, focus and change the volume of the A scan as well as adjust certain things for the image to be accurate. It is important to ensure that the image does not convey something false,” said Logan. “The smallest and thinnest parts increase the diffi culty of interpretation because the echoes of the interface become really tiny and close together. It causes an overlap of echoes, and you end up having to adjust the frequencies used. As you go higher up in frequency, it is more diffi cult to manage the transducers.” Like other companies, California Brazing considered bringing ultrasonic testing in-house, but to do it well, it needs someone who can read the images and interpret them well. Ager said: “It is not easy to fi nd people who have that depth of experience. We have a very good working relationship with PVA TePla. As a result, there is very little interaction needed because they are familiar with our process and types of products.” California Brazing typically gets its
results from PVA TePla in a few days, which it then follows up if needed, to say, focus further on a particular area or at a certain level.
CONTACT:
PVA TePla
www.pvateplaamerica.com
automationmagazine.co.uk
Automation | March 2022
25
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