where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

Airstar Inc.
Application of the newest technologies, such as air-coupled ultrasound, digital instrumentation, signal processing, and transducer technology.
771 views
Technical Discussions
LANRE ALAPINI
NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA, Nigeria, Joined Nov 2008, 3

LANRE ALAPINI

NDT Inspector,
NDT TRAINING AND TESTING CENTRE HOUSTON TEXAS USA,
Nigeria,
Joined Nov 2008
3
06:27 Dec-09-2008
flaw checking

can any body explain the term lack of back wall reflection


 
 Reply 
 
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.


 
 Reply 
 
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.

Swamy
NDT Guru





 
 Reply 
 

Product Spotlight

YXLON Cougar EVO

Scalable small footprint X-ray inspection systems for assembly and laboratory applications. The
...
YXLON Cougar EVO series was designed to provide the "best-in- class" inspection solutions for SMT, semiconductor, and laboratory assembly applications, while maintaining a small system footprint for maximum convenience. With optimized software and hardware, these systems produce higher quality and more consistent results than other electronics inspection systems currently on the market.
>

Research and Applications Development For NDT

The Research and Applications Development (RAD) group is a newly formed team within Acuren dedicat
...
ed to tackling challenging inspection problems. Our focus is the development of novel, field deployable, advanced inspection techniques for use in cases where standard NDT methods are ineffective. We don't wait for new innovations, we engineer them. From concept to commissioning.
>

Research Center IDEKO develops an ultrasonic train wheel inspection system for CAF

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
>

Semi-Automated Phased Array Immersion System for Small Composite Parts

Turn-key semi-automated system as an improved and affordable solution for inspection of small comp
...
osite parts. Includes support table, immersion tank, scanner, PA instrument, PC, Analysis software, database, wedge management and other options.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window