Magnetic Particle Inspection

[SpecialtyTool]

I have a question but Im not sure it really belongs on this forumn but Im going to ask it anyways. We have a job that we have done before that involves heat treating, magnetic particle inspection, hard turning, and passivation. For some reason this job has been routed as the following

 

Magnetic Particle Testing

Heat Treat

Hard Turning

Passivate

 

Does that make sense? Im not familiar with Magnetic Particle inspection but to the best of my knowledge it checks for cracks and other flaws in the material's surface but wouldn't it make more sense to do this after heat treating since heat treating can sometime's cause cracks? Any advice is appreciated

[Goldorak]

I have a question but Im not sure it really belongs on this forumn but Im going to ask it anyways. We have a job that we have done before that involves heat treating, magnetic particle inspection, hard turning, and passivation. For some reason this job has been routed as the following

 

Magnetic Particle Testing

Heat Treat

Hard Turning

Passivate

 

Does that make sense? Im not familiar with Magnetic Particle inspection but to the best of my knowledge it checks for cracks and other flaws in the material's surface but wouldn't it make more sense to do this after heat treating since heat treating can sometime's cause cracks? Any advice is appreciated

 

any jobs here that require an MPI, it test was done just before shipping after all treatment and process, even after black oxide ...

[chris m]

We perform MPI from time to time and typically:

 

Rough turn (say .060 stock per surface, all forged or cast surfaces MUST clean)

Heat treat

MPI

Finish turn

 

Our parts are very high precision, very thin in some spots, and can have no nicks or dents, so we try REALLY hard not to send them out of the building after finish turning.

 

MPI before heat treating seems a little odd to me, but I am not a metallurgist.

 

C