Reaming

—Reaming removes a small amount of material from the surface of holes.

—It is done for two purposes: to bring holes to a more exact size and to improve the finish of an existing hole.

—Multiage cutting tools that has many flutes, which may be straight or in a helix are used. 

—No special machines are built for reaming. The same machine that was employed for drilling the hole can be used for reaming by changing the cutting tool.

—Only a minimum amount of materials should be left for removal by reaming. As little as 0.1 mm is desirable, and in no case should the amount exceed 0.4 mm.

—A properly reamed hole will be within 0.025 mm of the correct size and have a fine finish.