With sharpening, the most common substance used is metal, obviously. Metal sharpening is the process of refining the metal to a point or to create an edge, as in sharpening the blade of a knife or sword. So, metal is the most effective substance to use in this case. Furthermore, the most practical metals to use for this are harder metals. Steels and iron ores are the most effective metals to use in the sharpening process. More malleable metals, such as precious metals and aluminum, can be too weak to use for sharpening. However, if the aluminum piece is thick enough, sharpening can ensue. Finally, great candidates for sharpening come in all shapes and sizes, depending on the source of the sharpening. Overall, it is a very versatile function.
There are a variety of designs for parts that are to be sharpened. The first feature, though, is that they must be made out of the right metal, as previously mentioned. These parts must be of a harder metal such as steel or a thick soft metal such as aluminum. Secondly, these parts can come in virtually any size. Parts that are smaller, such as a small blade, can be sharpened with a small, flat edged sharpener. Parts that are larger will require larger sharpening tools, but still can be sharpened successfully. Finally, parts of any shape can be sharpened. Flat edges, such as blades, can be sharpened successfully as well as rounded items, such as pipes. While this will require different types of sharpening blades, but can be done nonetheless.