A Swiss lathe is a style of lathe in which the collet, or holding mechanism, is recessed behind a guide bushing. Swiss lathes are also be known as Swiss turning centers, Swiss automatic lathes or Swiss screw machines. A Swiss lathe is different from a traditional lathe in that the collet, which holds the bar stock, is not directly exposed to the tooling and bed of the lathe. This type of configuration allows this machine tool certain benefits over a traditional type of lathe.
The Swiss lathe's advantages over a traditional lathe is largely because it uses a guide bushing. The purpose of the guide bushing is to provide additional support to the stock material as the part is being turned or machined. The guide bushing fits closely, but not tightly, around the bar stock material. Supporting the bar stock material, a guide bushing functions in a similar manner as a steady rest would on the carriage of a traditional lathe.
Swiss-style lathes generally hold better tolerances on parts because the turning operations are performed within close proximity to this guide bushing. The guide bushing provides rigidity to the turned part because only a minimal amount of stock is exposed after leaving the bushing until the turning tools are engaged. With the rigidity that the guide bushing imparts on the stock, these machines are particularly well adapted for holding tight tolerances. Another payoff is the Swiss style lathe's ability to turn small-diameter parts or parts with large length-to-diameter ratios. Tool chatter typically is minimized because of the tool/guide bushing juxtaposition.
There are two types of Swiss lathe machine tools. Mechanical lathes use cams, gearing systems and mechanical linkages to move the headstock and manipulate the collet and tooling. These types of machines have been replaced in many places by computer numerical control (CNC) Swiss lathes.
A CNC Swiss lathe will utilize many computer-controlled components. A great number of these components can be adjusted while the machine is in operation. The advantage of a CNC Swiss lathe is that the precision of a traditional machine is maintained while the functionality of the machine is increased with the addition of a computer and its controlled components.
Modern types of CNC Swiss lathes might include multiple axis and live secondary tooling, moving tail stocks or secondary spindles. Depending on the desired part configuration, some Swiss lathes have the capability of turning and machining parts complete. This eliminates the need for secondary operations.
A disadvantage with all Swiss lathes is the bar stock remnants. These generally are longer than those found on a traditional type of lathe and generally would be considered scrap. Long remnants are the result of the configuration of the collet and guide bushing in this machine.