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Re: [MW:5802] MPI vs DPI

By Materials & Welding

Friends,

- Magnetic Particles Testing is USED on Metals  can take Magnetic Field, like all Steel and Iron Except for Gamma Iron and Austenitic Steel be it Stainless Ni-Cr or Manganese Steel - Parts.
- It basically a surface discontinuity test.


- I would like to correct as DPI can also be tested on Castings of any metal and or its process of production by which such castings produced, to check the Cracks etc, it works on the Principle of Capillary action of Liquid.
- The Die is poured on test piece, to be checked, after its proper surface cleaning, some local grinding etc, then Colored die is applied.
- After that the DIEs poured/spread allowed to go in all crevices and possible discontinuities, we intend to check.
- Then after reasonably 5 to 15 minutes the same part/test PC/surface is cleaned with dry cloth of cotton and then surface is cleaned by WET rinsed Cloth/cotton.
- This removes the apparent surface color, once then the Developer the Chalk powder is sprayed over the entire surface.
- The Chalk powder acts as sets on the surface and tried to catch the hidden and deep die went in to deep, shallow cracks and discontinuities.
- On such places where defects observed as above described, we get surface COLORED, same as die color, other places remains White same as developer Chalk spread remains white.
- Colored area than dressed suitably and welded or repaired as per various needs after V notch by fiber/dics-DC Wheel on Flexible chain Grinders, for such welded repair subject to pre and post welding heat treatment, to comply metal integrity.


- In depth test can be other tests, like (A) Ultrasonic testing (B) Radio Graphic Testing for detailed defect analysis etc.
- Hope these meets with your needs to address your issues at this point of time.

PCP Rawal
Manager Material Development-Life Cycle Services

METSO  Minerals (India) Pvt Ltd.
Foundry unit, Plot no. 611-612.
Odhav road, Opp. Vallabhnagar, Odhav,
AHMEDABAD 382415
Gujarat India

Phone Lines:+91-79-30260400-441
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Direct Line:+91-79-30260410
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From: Declan Foley <declan1foley@eircom.net>
To: materials-welding@googlegroups.com
Cc: mohammed helal <eng_hilal79@yahoo.com>
Date: 06/30/2010 02:21 PM
Subject: Re: [MW:5800] MPI vs DPI
Sent by: materials-welding@googlegroups.com





MPI is for ferromagnetic materials only. It is supposedly useful for defects of depth 6mm, but ask anyone who performs the tests and they will tell you it is not!

DPI can be conducted on any material. It is not recommended on materials that have porous surfaces such as castings and the like.

Strictly speaking they are both considered surface tests. As regards substituting one for the other, I have never come across any situation where you couldn't. What are you testing?

Declan

On 29/06/2010 17:35, mohammed helal wrote:
The major difference  is the DPI is only for the defects that open to the surface and the MPI  for the subsurface defect ( 6 mm deep).

Eng.MOHAMMED ABD EL-AZIM HILAL
        MECHANICAL ENGINEER
     CSWIP 3.1 - NDT (RT- MT - PT)
OTISHAN CONSULTANT ENGINEER
 00966-502612218  -  0020103124557


--- On Tue, 6/29/10, george.dilintas@gr.bureauveritas.com <george.dilintas@gr.bureauveritas.com> wrote:

From: george.dilintas@gr.bureauveritas.com <george.dilintas@gr.bureauveritas.com>
Subject: Re: [MW:5791] MPI vs DPI
To: "materials-welding" <materials-welding@googlegroups.com>
Date: Tuesday, June 29, 2010, 7:06 PM

Mpi  can be used only on ferromagnetic materials


----- Original Message -----
From: Amir Zakee Adnal [amirzakee@gmail.com]
Sent: 29/06/2010 16:52 ZE5
To: materials-welding@googlegroups.com
Subject: [MW:5787] MPI vs DPI



Dear all
What is/are major difference between MPI and DPI? Can MPI be
substitute with DPI? Is there any code or standard that allow such
substitution?

Regards,
Amir Zakee

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