James Boaden Sales, Midas NDT Systems Ltd., United Kingdom, Joined Jun 2002, 6
James Boaden Sales, Midas NDT Systems Ltd., United Kingdom, Joined Jun 2002 6
07:00 Dec-09-2008 Re: flaw checking ----------- Start Original Message ----------- : can any body explain the term lack of back wall reflection ------------ End Original Message ------------
Using ultrasonics, a signal is generated that reflects back from the back surface of a component (when generated outside the component some sound reflects off the front surface and some penetrates, this then reflects off the back surface).
You should always get reflections from the back surface unless something stops the sound reaching it. Lack of back wall reflection dictates that a defect has stopped the sound reaching the back surface and the area of lack of back surface will be the same as the planar area of the defect.
S.V.Swamy Engineering, - Material Testing Inspection & Quality Control Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787
S.V.Swamy Engineering, - Material Testing Inspection & Quality Control Retired from Nuclear Fuel Complex , India, Joined Feb 2001 787
07:36 Dec-09-2008 Re: flaw checking ----------- Start Original Message ----------- : can any body explain the term lack of back wall reflection ------------ End Original Message ------------
Lack of back wall reflection or echo means that the transducer is not receiving the ultrasound signal reflected from the back surface (opposite side of the test object). This can happen due to one or more of the following reasons:
It is assumed that the instrument and the probe are working and that the range has been calibrated properly.
Very rough surface resulting in poor coupling
Highly curved surface resulting in sound not entering the test object
Lack of parallelism between the test surface and the back surface, for example a wedge
Sintered material with lot of porosity.
We had some interesting experiences while testing hot rolled austenitic stainless steel plates and tungsten-copper blocks. If any one is interested, I will share. Or I may submit a short case study like paper.
The Basque Research centre IK4-IDEKO has developed a state-of-the-art ultrasonic inspection system f
or the train wheel. This system secures a sound condition of train wheels and is thus a significant contribution to rail transport safety. The device was delivered to CAF recently and its use allows the manufacturer to become an approved supplier of rolling stock in Italy, as it meets the demanding homologation standards of this country. \\\\r\\\\n
The Athena Phased Array system, manufactured by WesDyne NDE Products & Technology, consists of a pha
sed array acquisition system and PC running IntraSpect software. A PC is used to perform acquisition, analysis and storage of the data. System hardware is capable of operating up to four data sets with any combination of phased array or conventional UT probes. NOW AVAILABLE IN 64-64 CONFIGURATION.