In the large family of metallographic consumables, there are many items with similar functions and applications. Typical examples include metallographic sandpaper and diamond grinding discs. Both of these consumables are used for rough grinding of samples. Many newcomers to the field are often confused: since these two have similar functions, how should I choose between them?
In the preparation of metallographic samples, besides cutting and mounting, the most crucial step is arguably the grinding and polishing process. Assuming that the cutting process does not produce deep, irremovable defects, and the mounting is done correctly, then the key lies in mastering the grinding and polishing techniques. Furthermore, with proficient sample preparation techniques, the quality of the sample preparation depends on whether the consumables chosen for each grinding and polishing step are appropriate. Both metallographic sandpaper and diamond grinding discs are used in the coarse grinding process, but there are differences in their applications. Understanding these differences will allow for appropriate selection.
Diamond grinding discs, with diamond abrasive particles ranging in size from 240μm to 6μm, are particularly suitable for preparing samples of high-hardness or ultra-hard materials with a hardness greater than 150HV, such as ceramics, glass, thermal spray metal coatings, and cemented carbides. One diamond grinding disc can replace at least 100-200 sheets of silicon carbide metallographic sandpaper. This is where the advantages of diamond grinding discs become apparent. Typically, when using diamond grinding discs for rough grinding, unlike using metallographic sandpaper which requires at least two to three different grit sizes, one step is sufficient. They offer consistently high material removal rates, wear resistance, and a long service life while maintaining excellent grinding performance, easily producing samples with perfect edge retention and flatness! These are the application characteristics of diamond grinding discs.
Silicon carbide metallographic sandpaper uses silicon carbide particles as abrasive grains, with particle sizes ranging from 260μm to 5μm. For materials with hardness below 150HV or slightly harder materials with good ductility, using silicon carbide metallographic sandpaper for rough grinding is still the most appropriate choice, ensuring rapid material removal and a uniform surface finish.
In summary, the choice between metallographic sandpaper and diamond grinding discs for rough grinding depends on the hardness of the material. Diamond grinding discs are suitable for preparing material samples with a hardness of 150 HV or higher, while metallographic sandpaper is best for materials with a hardness below 150 HV, or for materials that, despite being hard, have good ductility.
