What Is a Live Center?
A live center is a type of center that is a component of a machine tool, such as a lathe. It is sometimes called a turning center.
The center is attached to the headstock of a lathe or other machine tool and is used for centering during cutting operations and for maintaining the center of rotation of the workpiece.
There are two types of centers: fixed centers and live centers. The live center is a center with a built-in bearing and has the feature of reducing friction at high speed rotation compared to the fixed center.
Uses of Live Centers
Live centers are used to support rotating workpieces on a variety of machine tools, such as ordinary lathes, NC lathes, grinding machines, gear grinding machines, hobbing machines, and polishing machines.
While fixed centers that do not incorporate bearings have limited rotational speed due to friction caused by rotation, live centers can perform high-speed rotational machining because friction is reduced by bearings.
On the other hand, live centers are not suitable for high-precision machining because bearing rotation affects machining accuracy.
Characteristics of Live Centers
Live centers have a built-in bearing in its body and can hold a workpiece in conjunction with the spindle of a machine tool such as a lathe. The live center holds even long workpieces stably and prevents the workpiece from swinging even when machining at high speeds. Because bearings reduce friction, live centers also have the advantage of a long service life.
Live centers have a thicker header due to the built-in bearing. Therefore, depending on the shape and diameter of the workpiece, the tool (byte) and the center may interfere with each other and machining may not be possible, so interference between fixtures must be checked before machining.
The live center has a built-in bearing in the header, which makes the fulcrum distance longer, and a load moment proportional to the distance is applied to the tip of the center. A longer fulcrum distance will create greater deflection during processing. Therefore, live centers have the disadvantage of being inferior to fixed centers in terms of rigidity and accuracy.