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 -

482 views
Technical Discussions
James Dolfi
Director
ford, USA, Joined Oct 1999, 8

James Dolfi

Director
ford,
USA,
Joined Oct 1999
8
00:42 Oct-07-1998
Ultrasonic testing of spot welds

(Here is the completed version of the message 2 days ago)

The following is quoted from the paper on testing of autobody spotwelds.

'A modified ultrasonic testing method clearly detects stick welds and
cold welds, this is not possible with normal ultrasonic methods.
When testing under production conditions, 98% of the welds tested are
correctly evaluated, i.e. values obtained from the ultrasonic test
satisfactorily corresponded to the results from the teardown test.'
The link to the paper is: http://www.ndt.net/article/0498/spotw/spotw.htm

The above quoted statement would be true of most testing of autobody
spotwelds for the following reason.---

The body welding performance is typically very high and can reach 98% or
more. When an operator calls all welds good he can only be wrong 2% of
the time. If the report claims 98% correlation or 98% reliability I believe
that is misleading the readers to believe the testing system is capable of
accurately detecting both good and bad welds (with one calibration
setting). I have read detailed reports that do just as outlined above.
They report 98% accuracy but the item under test had 98% good items (welds)
in the test population. I could claim the same accuracy and be correct by
simply reporting all welds are good!

The way to present reliability data is to include the ALPHA and BETA
error data along with the claim of reliability for the test system. As
mentioned in other articles, the way to report could be:

1-ALPHA * 1-BETA = TEST RELIABILITY

Where:
ALPHA is the proportion of good called bad
BETA is the proportion of bad called good

I believe that a standard method of reporting or at lease the
computational method used to establish reliability should be included in any
such report.

Is there a standard with which you expect data to be reported?
Would you please comment on the appropriate measure of a
checking-gauge's performance?

Note:
My concern is that the measurement system should reject bad items and
not reject good items. Any checking system looses effectiveness when it
begins to reject good or accept bad items. My present requirement for
testing is 3% alpha (max) error and 15% beta (max) error (without
re-calibrating the system). Using the above 3% and 15% requirements,
the system only has to be about 82% reliable.



    
 
 
rasul maleki
rasul maleki
03:37 Mar-04-2002
Re: Ultrasonic testing of spot welds
dear,i studid your paper and enjoyed that.please send me more information about the method of your testing and describe me how did you do that.my email is maleki_ir@yahoo.com
thanks alot.


    
 
 

Product Spotlight

NDTkit RT

NDTkit RT, TESTIA's Digital Radiography software The NDTkit product line software for X-ray analysi
...
s. NDTkit RT is a software benefiting from the Ultis kernel which is dedicated to radiographic image analysis. It offers a set of tools and filtering processes to assist RT operators in finding relevant flaws.
>

Cygnus 6+ PRO Multi-Mode Ultrasonic Thickness Gauge

The Cygnus 6+ PRO thickness gauge is the most advance gauge within the Cygnus range with key featu
...
res including: comprehensive data logging; A-scan and B-scan display; manual gain control; Bluetooth connectivity; and much more. With its unique dual display and three measuring modes (Multiple-Echo, Echo-Echo and Single-Echo), this surface thickness gauge offers maximum versatility for inspections.
>

PROlineTOP Plug & Play Ultrasonic inspection device

As Plug & Play solution it units all control and operation elements in a small housing and therefo
...
re replaces the typical control cabinet...
>

Lyft™: Pulsed Eddy Current Reinvented

PEC Reinvented—CUI Programs Redefined Corrosion under insulation (CUI) is possibly the greatest u
...
nresolved asset integrity problem in the industry. Current methods for measuring wall thickness with liftoff, without removing insulation, all have severe limitations. Eddyfi introduces Lyft — a reinvented, high-performance pulsed eddy current (PEC) solution. The patent- pending system features a state-of-the-art portable instrument, real- time C-scan imaging, fast data acquisition with grid-mapping and dynamic scanning modes, and flexibility with long cables. It can also scan through thick metal and insulation, as well as aluminum, stainless steel, and galvanized steel weather jackets. Who else but Eddyfi to reinvent an eddy current technique and redefine CUI programs. Got Lyft?
>

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