The lathe is the oldest machine tool and has adapted to new technologies and to the needs of the machining industry. Today there are different types of lathe, such as the CNC vertical lathe, which is used to machine very large parts.
What is a CNC vertical lathe?
The vertical lathe is one of the many types of lathe used in the machining industry. This type of lathe is used to machine large parts. These machines are characterised by a vertical spindle and a rotary table that sits on the horizontal plane; this allows the lathe to support large parts of great weight and volume. Such parts could not be machined on centre lathes, for example. On a traditional vertical lathe, i.e. one that does not use CNC technology, the rotary tables can have diameters of one to fifteen metres.
The vertical lathe allows the manufacture of cylindrical and conical parts thanks to the rotation about the axis. These lathes perform three basic machining movements:
- A main movement that removes material by metal cutting.
- A feed movement that sets the path followed by the cutting tool.
- An infeed movement, i.e. the depth at which the cutting tool must work to remove material.
Thanks to technological progress, there are lathes that operate by computer numerical control (CNC). The CNC vertical lathe is equipped with a computer and follows its instructions, contained in software, to know which tools, movements and speeds to use for machining. The CNC vertical lathe, which works on the X and Z axes, is used, for example, to machine automotive parts.
CNC technology
The CNC vertical lathe, like all machine tools that work with this alphanumeric language, requires sophisticated programs to operate. To work with CNC, a prior design of the part to be machined is required; this is created using CAD and CAM software. CAD is used to design the part on a computer and CAM to translate it into CNC language. Once the design is complete, it is loaded into the machine's computer.
The operator can enter manually the specific commands or instructions for the machine to do its work and follow the design created.
Why use a CNC vertical lathe?
CNC technology brings major advantages to the machining industry. TheCNC vertical lathe, also known as a VTL (vertical turning lathe), is ideal for machining very heavy parts. These parts are clamped in the chuck or head, which, like the part, is very large. A CNC vertical lathe can machine a very wide range of diameters, from one metre to more than twenty metres.
In addition, as the parts are placed in a vertical position, less clamping force is needed than on centre lathes or horizontal-bed lathes; this keeps the part firmly in place and also prevents deflection or deformation. Moreover, the parts turned on this type of machine tool can be not only very heavy but also relatively short; these include discs, wheels, bearings and even aerospace components.
On a CNC vertical lathe much greater cutting forces can also be applied, which increases the metal removal rate per minute (RPM); this shortens turning cycles. Thanks to this, vertical lathes are machines with much higher productivity than centre lathes. Another advantage of vertical lathes is that they take up little floor space in the machine shop, as all their parts and components are arranged in the vertical plane. Moreover, they rarely require a tailstock.
And how are large parts handled? To fix the parts on the table, hoists or overhead cranes are used if they are very large and heavy; if not, it is possible to use robotic systems. Finally, thanks to CNC, productivity increases, machining times and labour are reduced and, as a result, production costs also fall.
Vertical lathes have guideways mounted on two vertical columns, which are parallel and joined at the top by a crossbeam. The toolholder carriage of this machine moves horizontally along the crossbeam. On CNC vertical lathes, the toolholder can be changed in less than a minute with great precision, as tool changing on this machine is automatic, which also reduces idle time.