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 -

3874 views
Technical Discussions
anjafo
NDT Inspector
Norway, Joined Aug 2009, 204

anjafo

NDT Inspector
Norway,
Joined Aug 2009
204
00:10 Nov-05-2009
Eddy Current V's DPI/MPI

Would Eddy Current find everything DPI/MPI could?

 
 Reply 
 
Godfrey Hands
Consultant,
PRI Nadcap, United Kingdom, Joined Nov 1998, 307

Godfrey Hands

Consultant,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
307
08:30 Nov-05-2009
Re: Eddy Current V's DPI/MPI
In Reply to anjafo at 00:10 Nov-05-2009 (Opening).

Hi Anjafo,
In theory, Eddy Current should find everything that DPI or MPI will, but there are certain limitations.

MPI is field direction sensitive, so you need to be certain that you have covered the component or area with crossing magnetic fields.
The same is applicable to Eddy Current. This will not easily detect a crack when the probe runs along the length of the crack, so once again, you need to double inspect at right angles to the first inspection to be certain of detecting the cracks.

Also when it comes to borderline defect dimensions, there are some limitations.
In a laboratory environment with experimental Eddy Current equipment, we have been sucessful in reliably detecting cracks of 0.020mm deep, whilst with a very sensitive penetrant or magnetic test, detection of smaller defects could be possible. Here however surface finish is critical for all three methods.

Eddy current can also detect defects under a thin non-conductive coating (like MT, but unlike PT).

Regards,

Godfrey

 
 Reply 
 
Jim Draper
Consultant, ASNT Level III MT PT RT VT
Draper NDT, USA, Joined Jul 2009, 99

Jim Draper

Consultant, ASNT Level III MT PT RT VT
Draper NDT,
USA,
Joined Jul 2009
99
20:32 Nov-05-2009
Re: Eddy Current V's DPI/MPI
In Reply to Godfrey Hands at 08:30 Nov-05-2009 .

DPI will is not limited to electricaly conductive material. Also, I have used direct current fluorescent MPI to locate flaws 1/4" deep. Of course that is limited to ferromagnetic material, while eddy current can be used to test other electricaly conductive materials.

 
 Reply 
 

Product Spotlight

Eddy Current inspection : RotoETscan Rotating Head

The rotating head RotoETscan detects the presence of longitudinal surface or sub surface defects a
...
t high speed. The rotating head is often installed directly on the production line. It is generally dedicated to the control of long products such as tubes, bars and wires, made of ferrous or non-ferrous material. It can also be used for inspection of small parts (billets).
>

OPBOX with standard software is able to do all types of inspections and measurements: flaw detection in welds and materials, scanning of objects, testing composite materials, forged and moulded pieces, many UT inspections, measurements of properties of ma

Typical applications: UT measurements with pulse technique, Measurement of thicknesses also at hig
...
h temperatures, Measurements of properties of materials, including fluids and gases We are delivering a standard version of the software (for any Microsoft Windows up to 10 x64 with Microsoft Hardware certification report Approved) and for special needs: SDK with ready to use examples for LabView, MATLAB x64, C++ wrapper for dll, Python and Linux., and also low-level description of how to control our devices directly from any USB tools
>

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.
>

TESTD-PT SYSTEM

Pulse thermography is a non-contact test method that is ideal for the characterization of thin fil
...
ms and coatings or the detection of defects. With a remarquable short test time and a high detection sensitivity, the Telops TESTD-PT is the perfect tool for non- destructive testing. With such high frame rates, it is even possible to investigate highly conductive or diffusive materials.
>

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