Reaming is a mechanical process that creates precision holes, typically after drilling, by rotating a precision cutting tool into a hole sized slightly under the diameter of the reaming tool.
The main advantage of reaming is the high tolerance of the resulting hole and smooth internal surfaces. The process is applied to cylindrical holes. Example applications include press fit holes, slip fits, holes where minimal play is required, etc.
The tooling involved are typically stock items although custom reamers are often required for larger holes.
Cost reduction options are primarily to minimize hole depth and to avoid large diameters due to the expense of large diameter reamers.