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 -
Technical Discussions
James Dolfi
ford, USA, Joined Oct 1999, 8

James Dolfi

Joined Oct 1999
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:


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?

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

Ultrasonic tomograph for imaging of concrete structures А1040 MIRA

Applicable for concrete inspection allowing imaging of the internal structure of objects from conc
rete, reinforced concrete, different stones. The operation applies pulse-echo technique at one-side access to the object. The instrument is feasible for concrete inspection for searching conduct ducts, conduits, detection of foreign inclusions, holes, honeycombing, cracks and other concrete defects.

Teletest Focus+

Teletest Focus+ electronics have superior capabilities than rivals on the market. Beyond the usual
test features, Focus+ has 24 transmit channels and 24 receive channels, with an additional on-board switching capabilities. The instrument's frequency range is 10–300 kHz.

Aerospace Systems - Automated Ultrasonic Inspection

USL are specialists in the design and manufacture of turnkey ultrasonic inspection systems for aer
ospace applications. From monolithic composites to complex honeycomb structures. This video shows just a few examples of what is possible, find out more at: www.ultrasonic-sciences.co.uk

FD800 Bench Top Flaw Detectors

The bench-top FD800 flaw detector range combines state-of-the-art flaw detection with advanced mater
ial thickness capabilities. Designed for use in the laboratory these gauges are the tool you need for all your flaw detecting needs.

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