A rotary surface grinder, also known as a rotary grinder or Blanchard grinder, is a machine tool used for precision grinding of flat or circular surfaces. It utilizes a rotating grinding wheel to remove material from the workpiece and achieve the desired surface finish or dimensional accuracy.

The rotary surface grinder is primarily used for the following purposes:

1. Surface Grinding: The main function of a rotary surface grinder is to grind and smooth the surface of a workpiece. It is particularly useful for grinding large, flat surfaces or surfaces with complex contours. The rotating grinding wheel moves across the workpiece, removing material and creating a flat or finished surface.
2. Flatness and Parallelism: Rotary surface grinders are capable of achieving high levels of flatness and parallelism on workpieces. This is crucial for applications that require precise mating surfaces, such as mounting surfaces for machine components or the production of precision tools and dies.
3. Thickness Control: The grinder can also be used to control the thickness of a workpiece. By removing material from the surface, the grinder can achieve the desired thickness and maintain uniformity across the workpiece.
4. Surface Finish: Rotary surface grinders can improve the surface finish of a workpiece. Depending on the type of grinding wheel and the grinding parameters, the grinder can produce a range of surface finishes, from smooth and polished to rougher textures suitable for specific applications.
5. Material Removal: The rotary surface grinder is capable of removing significant amounts of material quickly and efficiently. This is particularly useful for removing stock from large workpieces or for removing surface defects, such as weld beads, in preparation for further machining or finishing processes.

Rotary surface grinders find applications in various industries, including aerospace, automotive, tool and die manufacturing, and precision engineering. They are used for grinding large workpieces, such as castings, forgings, plates, and precision components, to achieve the required surface finish, dimensional accuracy, and shape. The versatility and precision of rotary surface grinders make them valuable tools for achieving high-quality surface grinding results.