* The hole needs to be very precise in diameter. Reaming produces a highly accurate, smooth, and consistent hole.

* The hole needs to be perfectly round and straight. Reaming can correct minor imperfections and ensure the hole is true to its intended shape.

* The hole needs to be deburred. The reaming process removes any burrs or rough edges from the hole.

* The hole needs to be finished to a specific surface finish. Reaming can achieve a very fine surface finish, which can be critical for certain applications.

* The hole needs to be enlarged slightly. While reaming primarily creates holes to a specific size, it can also be used to enlarge existing holes that are slightly undersized.

Reaming is typically used after:

* Drilling: Reaming is often used after drilling to finish the hole to a precise size and surface finish.

* Boring: Reaming can be used to finish a hole that has been bored, especially if the hole needs to be very accurate.

Overall, reaming is a process used to achieve:

* High precision

* Smoothness

* Roundness

* Straightness

* Deburring

* Specific surface finish

It is a valuable process in various industries, including manufacturing, machining, and aerospace.