CNC Enables Four-Axis Turning without CAD/CAM System

The expanded contour machining cycle for Siemens’s Sinumerik controls now facilitates four-axis turning on lathes, enabling two turning tools, opposite one another, to machine a workpiece simultaneously for reduced machining time. In addition, the two turning tools can prevent workpiece distortion and improve dimensional accuracy, particularly on long, thin workpieces.

With these CNCs, operators can program the new machining process without a CAD/CAM system, Siemens says, and with just two additional parameters, the user can expand the machining process for one tool into a productive, balanced cutting process for two tools. The Sinumerik contour machining cycle automatically creates the CNC sequences.

In a four-axis process like this, a distinction is made between synchronous and asynchronous path control, with the channel-based Sinumerik control executing two independent CNC programs simultaneously. In synchronous machining, particularly suited for roughing and finishing, the cutting inserts are exactly opposite one another and move identically. The cutting depth is equally distributed over both cutting edges, making it possible to double the feed rate per revolution and chip volume. In asynchronous path control, used for roughing, the two tools move differently. In longitudinal turning, the cutting inserts work at different diameters, and in face turning they work at different Z positions. The chip volume relative to a tool can be roughly doubled due to the short waiting times for tool synchronization, the company says.