Company: TeMeCo
Knowledge - Metallography - How to prepare a sample
This explains the correct sample preparation
The most widely used technique for preparing materialographic samples for microscopic analysis is mechanical preparation. The surface requirements are dictated by the subsequent test, and the preparation process can either produce a perfect final surface with the true microstructure or simply machine the sample to a level suitable for a particular test.
The objectives of mechanical preparation include preserving all microstructural components, achieving a smooth and reflective surface that is free of grooves, deformations or foreign bodies, minimising sample costs and ensuring complete reproducibility.
Three techniques are used to remove material: grinding, polishing and lapping, which differ in the degree of surface deformation during processing. In general, mechanical preparation uses abrasives with increasingly finer grits to remove material from the surface until it meets the desired requirements.
First, the sample is cut to the desired size and mounted on a suitable holder. The sample is then roughly sanded with a sanding disc or sanding belt to obtain an even and uniform surface. In the rough grinding phase, impurities, surface defects and deformations caused by cutting or other previous treatments are also removed.
The sample is then processed in a finer grinding stage to obtain an increasingly smooth surface. Depending on requirements, this can be continued by polishing or lapping to achieve an even smoother surface. Polishing is carried out with a fine abrasive paste and a rotating polishing cloth disc, while lapping uses a smooth, flat plate with an abrasive liquid.
During the entire preparation process, it is important to keep the sample clean and cool to avoid deformation and distortion of the sample due to overheating or contamination.
At the end of the process, the preparation should have a perfect final surface with a genuine microstructure and without grooves, deformations or foreign bodies.
Products
Grip Engineering – Roller grips
Shimadzu – Very High Cycle Fatigue
Used drying and climate chambers
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