Driven tools (live tool holders) for lathes

What is live tooling on a CNC lathe?

To answer the question of what live tooling is, we need to recall what traditional lathe machining is. The classic layout of a lathe consists of:

1. The bed
2. The front stationary headstock which contains the lathe spindle, into which the workpiece (a rotating body) is clamped
3. A movable carriage for mounting the cutting tool, either directly or through universal holders or a turret. The carriage can move along the Z and X axes
4. The tailstock for mounting the center. It moves along the Z-axis to clamp long workpieces or to hold a drill.

Machining a workpiece (rotating body/shaft) is performed by rotating it in the spindle and advancing the cutting tool, which is mounted on the carriage. The cutting tool is always aligned with the height of the workpiece. Consequently, due to the limitations of the standard lathe layout, drilling holes is possible only from the face of the workpiece and only along the central axis, with the drill remaining stationary while the workpiece rotates. Drilling off-center on the face or on the cylindrical part of the workpiece is not possible, nor is any milling that requires the rotation of the workpiece. Until the invention of live tooling, all such operations were performed in secondary processes on a milling machine.

But let's return to the question of what is live tooling and how its invention helped overcome the limitations of lathe machining described above? The word "Live" means the rotation of a cylindrical tool (end mill, drill, etc.) in the turret of a lathe.

This rotation can be achieved in three ways:

• By supplying coolant – special mechanism where liquid initiate the movement of the drive
• By supplying compressed air – special mechanism where liquid initiate the movement of the drive
• By the operation of an electrical motor and transferring torque to the tool through a coupling of the driven block.

The first two methods are mainly used on universal machines and have a number of limitations which we will not cover in this article.

The third method is used on most CNC lathes with live tooling function, which we will focus on.

That is, a turret head and a motor for live tooling are installed on the lathe's carriage. The cutting tool is mounted in live tooling blocks, which engage with the motor.

Live tooling blocks are divided into two main types.

• Axial blocks. For machining the face of the workpiece

• Radial blocks. For machining the cylindrical surface of the workpiece

As you may have noticed, depending on the type of turret, both axial and radial blocks can be straight or angled.

The introduction of live tooling has transformed the lathe into a hybrid lathe-milling machining center with a wide range of operations. On such a lathe-milling machining center (it is quite appropriate to use the word "center" since all models have a tool changer), in addition to lathe operations, drilling, milling, engraving, and other types of operations can be performed.