How Is a CNC Lathe Automated?

Automation in CNC Lathes

Automated CNC machine tools are equipped with components that further increase their ability to run automatically. All automation components are controlled in a coordinated way by the machine’s computer numerical control system.

Basic Structure of an Automated CNC Lathe

A second driven work spindle, or opposing spindle, makes it possible to machine the second side of a workpiece. After one side of a turned part is machined, the system can automatically remove it from one lathe chuck, clamp it in the opposing chuck, and machine the other side.

Tool Turrets and Driven Tools

CNC lathes are equipped with one or more tool turrets for rapid tool changes. A simple turret holds fixed tools, and a single turret typically carries 10 to 20 turning tools. By rotating and traversing the turret, a tool can be brought into the machining position. The tools selected for a turret should complete all turning operations for one workpiece without requiring new tools to be clamped into the turret.

When a standard CNC lathe is configured as a turning center capable of complete machining, the turret must drive tools for milling and drilling. In addition to a turret holding fixed turning tools, the machine therefore needs another turret or tool holder that can drive milling cutters and drills. With this type of turret, face and side milling and drilling can be carried out while the spindle is stationary.

When the work spindle is configured as a controllable, finely adjustable C axis, with increments of 1/1000 degree per step, and is used with driven tools, precision contours can also be milled and holes drilled on the outside surface of a turned part.

Other automated peripheral equipment, including devices for conveying and removing raw material or blanks, completes the automation of a CNC lathe. Although the control system for this loading and unloading equipment operates as a separate peripheral system, it is networked with the CNC machining program and operates in coordination with the lathe. This supports low-labor or unattended machining.

Automatic Bar Feeders

For turning bar stock, CNC lathes are typically equipped with an automatic bar loader installed directly on the machine. The lathe requires a driven spindle with a hollow bore. For example, a 3 m bar rests on an inclined magazine rack and rolls into the feed channel. A feed pusher then pushes the bar from the rear through the hollow spindle and into the lathe chuck, where it is clamped. Once the machining cycle begins, the completed part is released and discharged from the machining space. The chuck then opens and bar stock for the next part is fed in.

Loading and Unloading Small and Large Blanks

When small preformed blanks, such as forged bearing housings, are loaded with equipment fitted to a CNC lathe, a pulse conveyor can deliver blanks into the machining space. A rotary loading device that travels and carries a workpiece gripper picks up individual workpieces and places them in the lathe chuck. After machining, the workpiece drops onto an inclined chute and is delivered by an outfeed conveyor to a workpiece pallet or a grid-type container.

When turned blanks are made from large bar profiles or large forged blanks, a chain conveyor is used to transport the blanks and a gantry loader handles the workpieces. In this arrangement, a CNC lathe is fitted with a blank pulse conveyor at the side. The gantry loader, equipped with a gripper, picks a blank from the conveyor, travels over the CNC lathe, lowers the blank into the machining space, and loads it into the lathe chuck. After machining, the loader removes the finished part and transfers it to the finished-part conveyor.