Warm rolling of aerospace fasteners

The shortage of aerospace quality fasteners is causing production delays for new aircraft programs and highlighting the need for new and better production processes.

 

The shortage of aerospace-quality fasteners led to production delays for the new aircraft program and highlighted the need for new and better production processes. As a result, we applied our expertise to determine how to improve the way threads roll on them.

For thread diameters of 3/8" and larger, rolling is typically done in rolling machines with three cylindrical dies. These machines have been the preferred choice for cylindrical die rolling because they use a fixed vertical rolling axis and the dies are driven uniformly to roll the centerline, eliminating the need for work support inserts. In addition, the vertical rolling axis provides a stable blank loading position.

However, the maximum die diameter that can be used in a three-cylinder die configuration without die collision is only about five times the diameter of the thread to be rolled. For threads 5/16" diameter and below, this limits the spindle diameter to a level that is normally insufficient to carry the rolling loads required for hard materials. It also reduces the available working surface of the die, thus limiting die life.