What Is a VTL? Oh It’s a Vertical Turning Lathe!

Posted on Jul 28, 2020

Vertical Turning Lathe

There are two types of CNC turning centers: horizontal and vertical.  Horizontal turning centers are the most common.  Vertical turning centers are typically called a vertical turret lathe or VTL.  With a horizontal turning center, the spindle is horizontally oriented, and tools are mounted out of the side of tool holder and cut across the workpiece.  With this type of turning center, gravity pulls the chips away from the workpiece.

The Difference Between Lathes and Turning Centers

The CNC vertical turning center is virtually the same as the CNC horizontal turning center but is upended, allowing the headstock to sit on the floor and the faceplate to become a horizontal rotating table.  This is beneficial for machining large, heavy and short workpieces.  In this case, gravity contributes to seating the workpiece into the work holding.  However, chips may become a problem as gravity does not necessarily help chip evacuation from the workpiece.  An inverted vertical turning center is like the afore mentioned but reverses the position of the spindle and jaw chuck. An inverted vertical turning center is like the afore mentioned but reverses the position of the spindle and jaw chuck.


Turning Uses and Applications

Aerospace, automotive, medical, oil and gas industries etc. These are some of the industries in which CNC turning centers are used. These machines are particularly good at machining round metal parts, rods, pipes, gears, etc. Multitasking is the word that best describes turrets driven by live tools. In most cases, lathes are today commonly called CNC lathes and CNC turning centers. A CNC lathe is a simpler 2-axis machine (X and Z axis) that is computer controlled and generally has one spindle. They are usually of the flat type and may have only minimal protection around the machine and its paths.

CNC turning centers are also computer-controlled, but have more power and can have 3, 4 or 5 axes with more versatile capabilities and applications such as turning, drilling, threading and milling using energized tools with driven rotary tool head, auxiliary spindle (double spindles), Y axis and many turrets. They are usually oblique and have full machine housings to stop chip and coolant splashes in the machine. CNC turning centers have greater production capacity than CNC lathes.

:: See products : Turn Mill Machine


Lathe Components

Here are some of the most important parts of a CNC Lathe:

●  The Headstock

The headstock serves as a housing for the main spindle to which a jaw chuck is attached that holds the workpiece. The diameter of the hole or spindle rod determines the maximum diameter of the workpiece that can be mounted with the head. The headstock is usually on the left side of the lathe.

●  The Tailstock

The tailstock is mounted on the bed of the lathe, opposite the headstock and slides along it in alignment with the headstock Z-axis.  The primary function of the tailstock is to provide support to the workpiece being machined between centers.  The tailstock has a quill with a taper to hold tooling.  CNC turning centers with sub-spindles (or dual spindles) will have a second spindle in lieu of a tailstock.  The sub-spindle can move in the Z-axis longitudinally toward the main spindle under CNC control.  Sub-spindle enables the machining of the back-side of a workpiece without additional operator loading/unloading in the work process.

●  The Bed

The bed, usually made of cast iron, is the base on which various fixed and operational parts are mounted. It is connected to the head and extends from the head to the tail. It is located under the work area. The turret with tools and various tools move along the rails or paths of the bed along its entire length. Linear guides are better suited for rapid rapid movements and abrasive machining. Massive crates are better suited for heavier or intermittent cuts with better tool rigidity.

●  The Carriage

The trolley supports the cutting tool head, guiding it and sliding it against the workpiece. The main parts consist of a saddle, cross guide and tower. Turning centers with working turrets can have rotary tools driven for milling operations, which significantly increases the machine's capabilities and can reduce or eliminate second operations on workpieces.


When Is a Lathe Considered a CNC Turning Center?

Although there is no hard and fast rule to make this distinction, reasonable expectations for a CNC turning center usually start with the full machine housing. Next, the bed paths for the tailstock and carriage are separate sets that allow the tailstock and fixed supports to be positioned as needed without interfering with the carriage and tool head movements along the entire length of the bed. In many cases, the tailstock body position can be programmed under CNC control.

Live tooling allows the lathe to mill, drill, drill, turn and thread components. The benefit is reduced working time, which increases productivity and profitability. Companies usually offer a full range of CNC lathes with live tooling, dual spindles, Y axis, multiple turrets and robots that meet simple and complex applications and machining solutions.

Some vertical lathes have been designed with high performance users in mind. The turret-style machines have high-torque drives for the heaviest cuts, and the frame-style machine provides a greater level of support to increase accuracy and finish.

Massive castings and very wide systems ensure accurate and stable machining of all vertical lathes. Heavy gears, which are standard on larger models, allow material removal at high spindle speeds.

The feeding system ensures excellent vibration absorption and vibration-free cutting, even in demanding conditions such as threading, grooving, intermittent cuts and heavy roughing. For chuck sizes from 20 inches to 13 feet, there will definitely be a vertical lathe for machining the workpiece.

A vertical turret lathe is known for its ability to efficiently manufacture large, turned parts, such as mag wheels, bearing hubs, and gear blanks. VTLs offer many advantages over their horizontal cousins: Loading parts is easier, and even very large parts can be accommodated without increasing the surface of the machine.

However, VTLs have a significant disadvantage known to anyone who operates a vertical machining center - the chips fall onto the workpiece, where they are reprocessed.

Several machine manufacturers offer VTL to avoid this problem. By turning the spindle, chip problems are virtually eliminated. This approach also provides almost free automation. By using a spindle like a robot - lifting parts from an on-board conveyor or carousel and unloading them - throughput is increased without problems with robot integration, programming and gripper management.

:: Read more : Turning Center and the Corresponding Machining


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