A milling machine is a tool designed for wellbore cleaning and gauging (mostly utilized during workovers). It is comprised of a steel body with hard-metal granules in brass matrix soldered to its face and cylindrical body. The mill dimensions can range from 0.5 m and up in length and from 100 to 200 mm in diameter. It can be of a cylindrical, tapered or frontal design. The mill features an inner thread.