- The workpiece is held on the spindle while rotating at high speed.
- A cutting tool or center drill traces the outer or inner perimeter of the part, forming the geometry.
- The tool does not rotate and moves along polar directions (radially and lengthwise).
CNC lathes are extensively used, because they can produce parts at a much higher rate and at a lower cost per unit than CNC mills. This is especially relevant for larger volumes.
The main design restriction of CNC lathes is that they can only produce parts with a cylindrical profile (think screws or washers). To overcome this limitation, features of the part are often CNC milled in a separate machining step. Alternatively, 5-axis mill-turning CNC centers can be used to produce the same geometry in one step.
Some view Lathes as the only universal CNC Machine tool because a lathe can make all of the parts needed for another lathe. A lathe spins the workpiece in a spindle while a fixed cutting tool approaches the workpiece to slice chips off of it. Because of this geometry, lathes are ideal for parts that have symmetry around some axis that could be chucked up in the spindle.
CNC Lathes have at the very least the ability to drive the cutting tool under g-code control over 2 axes, referred to as X and Z. They may have a considerable amount of other functionality as well, and there are many variations on lathes such as Swiss Lathes.
The act of cutting a workpiece on a lathe is called "Turning".
Due to technological advancements, CNC lathes are quickly replacing some of the older and more traditionally used production lathes, such as the multispindle. CNC lathes come with a number of benefits. They can be easily set up and operated. They offer tremendous repeatability, along with top-notch accuracy in production.
A CNC lathe is typically designed to utilize modern versions of carbide tooling and processes. A part can be designed for customization, and the machine’s tool paths are often programmed using the CAD or CAM processes. However, a programmer can manually design a part or tool path as well. The resulting coded computer file is then uploaded to the CNC machine, and the machine will then automatically produce the desired parts for which it was programmed to design.
Turning is a machining process used to make cylindrical parts in which the cutting tool moves in a linear fashion while the workpiece rotates. Commonly performed with a lathe, turning reduces the diameter of a workpiece to a specified dimension and produces a smooth part finish. A turning center is a lathe with a computer numerical control (CNC). Sophisticated turning centers can also perform a variety of milling and drilling operations.