Corrosionpedia Explains Grinding

Grinding is a method of reducing the size of hard materials or sharpening tools, generally accomplished in several stages. To produce desired fineness of end products, grinding is done after crushing. For example, through crushing the mineral ore to below a certain size and finishing by grinding it into powder, the ultimate fineness depends on the fineness of dissemination of the desired mineral.

Grinding can be done wet or dry, depending on the process in use, but for dry grinding the materials first may need to be dried in cylindrical, rotary dryers.

Many machines are used for grinding, including:

• Hand-cranked knife-sharpening stones (grindstones)
• Handheld power tools such as angle grinders and die grinders
• Various industrial machines known as grinding machines
• Bench grinders often found in residential garages and basements

Grinding can produce very fine finishes and very accurate dimensions. It is usually better suited to the machining of very hard materials than is “regular” machining.

Property changes due to grinding include:

• Martensitic layer may form on the part, which leads to reduced material strength from microcracks
• Possible loss of magnetic properties on ferromagnetic materials
• Increased susceptibility to corrosion because of high surface stress

Grinding machines remove material from the work piece by abrasion, which can generate substantial amounts of heat. To cool the work piece so that it does not overheat and go outside its tolerance, grinding machines incorporate a coolant.