Grinding:
Surface grinding is done on flat surfaces to produce a smooth finish by rubbing. Make pieces sharp or smooth. The most common are to use grinding wheel or grinding machine.



Burnishing：
Burnishing is the plastic deformation of a surface due to sliding contact with another object, polish metal until it is smooth and shiny. The most common are roller burnishing or ball burnishing.






Polishing: 
Make pieces smooth and shiny by rubbing with a cloth or using an abrasive.



Buffing:
Polish with a soft cloth or a loose abrasive, which leads to a smoother, brighter finish than ploshing.a buffed surface has a mirror-bright finish.