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MAGNETIC PARTICLE INSPECTION FOR CASTING

Magnetic Particle Inspection (MPI) is an effective process for discovering flaws in investment castings. This method is best for detecting cracks and flaws on the surface and just below. It can be used on all alloys that can be strongly magnetized including irons and ferritic steels. Austenitic steels are typically not good candidates. After a casting is magnetized, very fine iron particles are applied to the surface. If there is a flaw, the magnetic field will be disrupted, and particles will concentrate in those areas, even if the flaw is very small. A hairline crack below the surface, not visible to the eye, will appear as a line of iron powder particles on the surface.

The test method process is quick and simple in principle and application. It is highly sensitive to the detection of surface and slightly subsurface linear indications, and indications appear on the actual test investment casting part. The test method process may often work through contaminant layers and coating thickness, and the method lends itself to automation and high-volume production inspection. Besides, it is less expensive than other more sophisticated methods of quality assurance.

Advantages of Magnetic Particle Inspection:

• It is quick and relatively uncomplicated.
• It gives immediate indications of defects.
• It shows surface and near surface defects, and these are the most serious ones as they concentrate stresses.
• The method can be adapted for site or workshop use.
• It is inexpensive compared to radiography.
• Large or small castings can be examined.
• Elaborate pre-cleaning is not necessary.

MPI in CFS foundry

Quality control is quite important for us to deliver high quality products. To be more professional and reliable, we are equipped with MPI equipment in CFS foundry, so that we can do MPI directly. The MPI in our foundry is wet method, which provides improved sensitivity for the detection of very fine surface flaws. We can detect a discontinuity with maximum depth 1/4 inch, but usually 0.050 to 0.100 inch depth is enough. For heat treated castings or machined castings, magnetic particle inspection should be done once casting blanks are completed. And there is no need to carry on further heat treatment or machining operation if there is any defect. Investment casting with defects tested by MPI will not be delivered to our customers.

To discuss your MPI requirements, please get in touch with our sales team.