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Manufacturing Process
 
 


Metallographic Examination

Metallographic examination provides the best means of identifying the defect which in turn quickly eliminate or reduce the defect and minimizing its cost of production and wastage due to rejects. The thickness of product coating could also be measured with this technique.

Types of Metallographic Examination
● Failure Analysis
● Grain Size
● Fracture Surface Analysis
● Plating Thickness


Sampling

Generally, defects are small, great care must be taken during sampling to ensure that the defect is not damaged or destroyed during sampling and preparation. The use of a microscope (magnification 3 to 25X) as shown above assists with this selection.
   
Cutting & Mounting

Most defects require a microscopic examination and this requires a cross section sample of the casting to be cut. This sample must be cut very close to the defect, but the cutting process must not destroy the defect. The sample is then mounted in a resin or plastic material. To enable the surface of the sample to be kept flat and to protect the edges of the sample.

Polishing & etching

The mounted sample is then ground and polished. Grinding and polishing requires significant skill and experience. If the surface is not flat, clean and free from residual scratches, it is not possible to properly examine the defect under a metallographic microscope.


   
Micro Examination

Casting samples are typically magnified from between 100 to 500 times for examination of casting or coating defects The use of this procedure is a very powerful tool as it enables an experienced person to identify the type of defect(s) that are involved and also see other structural detail that assists to identify the parts of the process that may be causing the problem.

 
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