What type of holes are classified as close ream holes for interference fits?

Close ream holes, which are designed for interference fits, are classified as ream holes because they are specifically finished to a tighter tolerance than standard holes. Reaming is a precision machining process that enlarges and finishes holes to a precise diameter and smooth surface, which is essential for creating a snug fit between two components.

In applications requiring interference fits, the amount of material removed during reaming is controlled carefully to ensure that the resulting hole is slightly smaller than the corresponding shaft or component that will fit into it. This discrepancy is intentional, as it allows for a tight, secure fit that can handle significant forces without slipping.

Understanding the characteristics of ream holes is crucial for aerospace assembly mechanics, where tolerances are critical for safety and performance. They differ from standard holes, which may not have the same level of precision or fit, and from other categories like close holes or precision holes, which refer to different types of hole specifications that may not directly pertain to the concept of interference fitting.