Editor for Modern Machine Shop Magazine, Chris Koepfer, once wrote, "a shop bought a milling machine to mill, a turning machine to turn, a drill press to make holes and so on." A turning machine with Y-axis live tooling can handle all of those operations - possibly in one setup.
A turning center equipped with live tooling is capable of receiving a solid chunk of raw material and - without any handling - can turn, mill, drill, bore, engrave, tap, and thread a ready-to-ship, finished product.
Certain twin-sided live tooling turrets can hold up to 24 different tools, removing the need for post-turning operations and additional setups.
Some shops have turning centers that also feature Y-axis motion, which expands the machining range of live tooling, creating a true four-axis machining center (X-Y-Z and C-axis).
Positioning a piece only once simplifies and ensures the success of machining relational geometry - features which share relationships. Koephfer further explains the importance of one-stop fixturing:
What often gets lost during the trip from the lathe to the machining center is the relationship of the holes to the major ID. Very accurate fixturing is needed on the machining center to assure these holes are the correct distance from each other and from the center of the bores...Obviously, on complex workpieces, feature relationships become even more critical.
In fact, relational features benefit greatly from a multiple spindle turning center. By having a chuck on both the main and sub spindles, a shop can continue operations (including live tooling) across the entire Z-axis of the part without any physical handling. Since the part is never removed from the machine, features on each end of the workpiece are in relation to each other.
By contrast, single spindle lathes require the operator to machine one end, then physically rotate the part to machine the other end - increasing labor cost and machine downtime.
Other capabilities - such as a bar feeder, parts catcher, chip conveyer, and vapor recovery system - make turning centers extremely cost-efficient for high-volume productions. Imagine turning and milling over a hundred pieces with only a single setup.