Rotary Transfer Machines automatically feed multiple work stations from a rotating turret. This combines automated part feed with multiple simultaneous operations, streamlining the machining process significantly. The rotary transfer technology indexes a workpiece from station to station via a rotary table, with operations performed at each station. The number of stations allow for easier balance between long and short operation cycles. Because the tools - rather than the workpiece - are rotating, it is possible to insert and machine nonround stock of virtually any shape.

Machining operations are typically holemaking operations (drilling, cross drilling, tapping, boring, counterboring, etc.) but can also include milling, turning, cutoff, broaching, crimping, internal and external recessing, threading, tapping, broaching, and other secondary machining and assembly operations. Although the rotary transfer machine is best suited for multi-million part runs, its flexibility also makes it effective for family-of-parts production. And while transfer machines are best known for very high volume production, advances have been made to help make them more efficient for shops that have seen lot sizes decrease.

Transfer machine technology is composed of basically two types - linear and rotary. The goal is the same for both - put a blank, bar, casting or forging in the first station and get a completely machined part at the other end.

Along the way, a workpiece can be turned end-for-end to perform back-working operations. For specific radial locations, the part can be rotated to any position. With each index of the table, a complete part is ejected.

With a large selection of workstations available on rotary transfer machines, cycles can be more easily balanced. Part cycle time is dictated by the slowest process in a sequence of processes. Ideally, each station's operations should take the same amount of time. That's a balanced cycle. In reality, this is seldom possible because different operations progress at different rates. With more stations available, feeds and speeds can be optimized - sped up in the slow stations and slowed down in the fast stations to produce a closely balanced cycle.

Even though the process historically looks for high volume, Seward Screw Products will entertain a number of parts and family of parts that are not high volume.