Reamers are used when high demands are made on the dimensions of boreholes in the metalworking industry, among others. Drilled holes are often inaccurate in size and not completely round, moreover, the surface of these holes is not smooth enough for certain applications. There are constructions where this is unacceptable. You can think of an axis that must fit exactly in a hole. In such a case, the hole is cleared to size after it has first been drilled to a slightly smaller size.
