Imported metallographic sandpaper is relatively expensive. If not fully utilized during use, it will be too wasteful. If used too much, it will affect the grinding effect of metallographic samples, prolong the preparation time, and may also cause difficulty in subsequent polishing, thereby affecting work efficiency. Therefore, it is important to grasp the timing of the use and replacement of metallographic sandpaper. To what extent is it appropriate to replace metallographic sandpaper?

Let's first understand the internal structure and usage principle of metallographic sandpaper.


The purpose of using metallographic sandpaper to grind the surface of the sample is to remove the surface deformation layer, and the subsequent fine sandpaper grinding is to remove the scratches from the previous coarse sandpaper, which is essentially a micro grinding process.


Principle of use: By using sharp grinding medium particles fixed on a paper substrate for rapid grinding, the deformation layer on the surface of the sample is removed. At the same time, the grinding medium particles participating in the grinding will be broken due to force, and their sharp edges and corners will be removed. The remaining part will be in the bonding layer, causing the surface to become blunt and the grinding ability to weaken accordingly, resulting in a lower removal rate. This increases the chances of friction contact between the sample surface and the paper substrate, The grinding medium particles that cause dullness cause new damage to the surface of the sample, which is commonly referred to as "; Plastic deformation is greater than sharp grinding particles;. Refer to the comparison chart of new sandpaper and worn sandpaper below, from which we can clearly see that the surface of worn metallographic sandpaper has been basically ground flat.

Using this worn old sandpaper to grind the sample, the surface of the ground sample appears smoother and more reflective than that of the new sandpaper. The sensory effect appears to be good, but this is only an illusion because if it is placed under a microscope, the actual effect will be seen, as shown in the following figure:

The left image in the above figure shows the surface of the worn old metallographic sandpaper after grinding, while the right image shows the surface of the sample after grinding with a brand new metallographic sandpaper. It can be seen that the grinding marks of the new sandpaper present a three-dimensional morphology image, overlapping each other more clearly; The surface ground with old sandpaper appears to be on a flat surface, with blurred grinding marks. In contrast, the deformation layer of this sample is deeper. Due to the planarization of the grinding marks and good reflectivity, the visual observation shows a mirror effect, resulting in a false image of more successful sample preparation.

In summary, to what extent is it more appropriate to replace metallographic sandpaper? The experience of pulse detection application engineers is that when a grinding process of a sample requires continuous repeated grinding for more than three times to produce a qualified surface, the old metallographic sandpaper used should be replaced, which not only does not waste but also makes its best use. If it continues to be used, it is really uneconomical, which is exactly what we expect. If you have any questions about the use of metallographic sandpaper, please feel free to discuss with our application engineers at Kemai Testing to help you solve your problems and make your work better!