Jun. 20, 2022
Want to learn all about CNC lathes, but not sure where to start? Well, you've come to the right place!
For those new to the industry, the variety, size and specialized uses of CNC (computer numerical control) machines used in manufacturing can be incredible - from lathes, mills and multi-axis machines to other machine tools.
To help you better understand what each type of tool is used for and how to use them, we're starting a new series on the basics of CNC machines.
In this article, we will focus on CNC lathes, including the following.
- Definition of a CNC lathe
- CNC lathe parts
- Uses of CNC lathes
- Programming a CNC lathe
- Types of CNC lathe
- Price of CNC Lathe
Lathes are considered the workhorse of manufacturing and have been around since the 19th century. Unlike their predecessors, today's CNC lathes are more sophisticated and automated.
The power factories around the world and are used for a wide range of applications.
So, what is a CNC lathe?
A CNC lathe, which operates using a computer numerical control (CNC) system and provides precise design instructions, is a machine tool in which the material or part is clamped and rotated by a spindle, while the tool that processes the material is mounted and moves various axes.
CNC lathes are typically used to machine parts where the material/part is clamped and rotated while the cutting tools are fixedly mounted for OD (outside diameter) and ID (inside diameter) operations, such as shafts and pipes. They are very suitable for parts with the same symmetry around an axis which can be stuck in the spindle (i.e. radial clamping).
A simple CNC lathe runs on 2 axes with the tool in a fixed position on a turret of 8 to 24 stations. The rotating action of the part is called "turning", so some types of CNC lathes are called CNC lathes.
Milling (where the tool moves around a fixed workpiece), boring and tapping (a tool that cuts threads in a hole) tools are usually driven by a separate drive system within the turret. Depending on the application, life tools (i.e. active tools) are mounted for axial or radial direction of operation. These can be found in 3-axis CNC lathes or CNC lathes.
Lathes with additional options, such as Y-axis, sub-spindle or specific selected automation options, are often called turning centers. These sophisticated machines are capable of machining complex parts - they go beyond the standard OD and ID turning operations and can combine milling, drilling and tapping operations to complete the part in one setup. From raw material to finished product, these integrated machines dramatically increase productivity.
What are the different parts of a CNC lathe and how do these different components of a CNC machine fit together?
In general, CNC lathes have the following main configurations.
● Inclined bed
● Flat bed
● Other types, such as Swiss-type, multi-axis, B-axis
Depending on their configuration, CNC lathes may have the following components.
The bed of a CNC lathe or CNC turning center forms the main foundation of the entire machine. It is the place where the different components of the machine are mounted. For example, the spindle frame that houses the machine's spindle; the tailstock body; the X and Z axis slides; the optional Y axis; and the sub-spindle.
Often referred to as the heart of the machine, the spindle consists of the spindle assembly and the spindle drive system. These are some of the moving parts of a CNC machine, and they include motors, gears, and chucks (more on these later). The C-axis drive, which helps position the material, will also be assembled with the spindle.
Tool holders are typically mounted on a turret disc (a rotating disc that allows tool positioning and switching) and they include fixed tool holders and life tool holders. The life tool drive system is built in.
The sub-spindle is separated from the spindle as an option and works synchronously with the spindle to complete the first and second cutting operations of the CNC lathe. This increases the efficiency and throughput of each cycle. When named the second spindle, this mechanism has the same capacity and power as the spindle.
A chuck is a vise like structure used to hold the workpiece to be machined. It is attached to a spindle that rotates the chuck and the workpiece simultaneously.
The guide rail allows the tool to move horizontally and vertically for a smooth cutting process. This construction is required to ensure durability, rigidity and maximum precision.
The spindle box consists of the main motor that holds the spindle on which the chuck is mounted. To ensure high performance, you need to consider whether your machine's spindle box can handle high torque at low speeds. For tough materials, this is an important consideration.
The tailstock is used to provide additional support at the opposite end of the assembly. This is necessary when machining long and extra-long workpieces, such as shafts.
The turret offers the possibility to change the tool needed for machining. Therefore, it is mounted on a tool turret. The size of the turret depends on the number and size of the tools that will be mounted on it.
Some of the available options include.
● CNC lathe Y-axis (for eccentric operation)
● CNC lathe part catcher (for automatic part unloading)
● CNC lathe feeder/bar magazine (a single bar is used in the bar feeder, while the tool magazine is used for automated machining involving multiple bars)
● MC - drives include milling, life tooling, and C-axis operation
● Various bed lengths to accommodate long axes or tubes
CNC lathes are typically used to perform/produce precise circles with outside diameter (OD) and inside diameter (ID). Depending on the needs of different industries, the machine can machine almost any kind of structure.
CNC lathes are commonly used in the oil and gas, automotive, aerospace, medical, electronics, mining, power plants, steel and paper mills, and shipbuilding industries, just to name a few.
Modern CNC lathes often come with life tools that can work on multiple axes. For example, they may include X and Y axes, combine a second turret with a different tool, or include a sub/second spindle. These features help to perform different milling, drilling and tapping operations more efficiently and flexibly.
The result is a complete or even complex part manufacturing process without the need to transfer the part to another machine for a second operation, such as a CNC milling machine or CNC machining center.
One of the common questions is: How to program a CNC lathe and what software is usually used for CNC machines?
Modern CNC lathes can be programmed in the following ways.
● directly on the machine using a modern CNC programming support system such as "Manual Guide I" (FANUC) or ShopTurn (SIEMENS).
● Offline using a CAD/CAM system. These usually involve more complex shapes or series of operations to be machined.
In most cases, the CNC lathe or CNC lathe should be able to handle one CNC program while the next CNC program is being built and programmed. This helps to make the manufacturing process more efficient and saves time and labor.
CNC lathes - how many axes?
Today, CNC lathes can be equipped with a variety of different axes to produce more complex parts without having to manually switch machines or tools. The different axes depict the way in which the machined part (or tool) can be positioned/approached and rotated during the machining process.
In this basic setup, the 2 linear axes can be used to perform OD/ID (i.e. cylindrical machining) and face machining, or to drill and tap in the center of the part. However, it does not allow milling to be performed.
In addition to the basic X and Z axes, a C-axis and life tooling system have been added. This allows parts to be positioned to perform standard milling operations, boring and tapping operations. Spiral milling operations involving slow simultaneous rotation of the part are possible.
Here, the Y-axis is added to the machine so that eccentric machining operations can be performed. This would be suitable for more irregular and complex operations.
In this type of machine, a second turret is added to the 3-axis CNC lathe (e.g. T2-2T). Such a machine has 2 axes on each turret (upper and lower turret), plus the C-axis on the rotating spindle. This makes it possible to use 2 tools on the part at the same time, thus significantly reducing cycle times.
Here, this lathe arrangement may include the following.
● 2 x C-axes (spindle and second spindle)
● 2 x turrets (upper and lower turrets, each with 2 linear axes)
● 1 x Y-axis in the upper turret
● 1 x second spindle, which can be moved towards the main axis to pick up parts
Of course, there are machines with more than 8 axes. However, these are highly sophisticated and complex machines that are not usually required for common manufacturing needs.
So how much does a CNC lathe cost and what should you ask when requesting a quote for a CNC lathe from a reputable CNC machine tool manufacturer?
To calculate the total cost of purchasing a CNC lathe, we need to consider the following points.
● Country of Origin
● Manufacturing process
● CNC machine dimensions
Learn more about these areas below.
The manufacturer and the country where the CNC lathe is made (Korea, Germany, Japan, Taiwan, China, etc.) have a big influence on the price.
How the CNC lathe is made
This will affect the quality and performance specifications of the machine and they include factors such as
● How much R&D and prototyping has been invested in manufacturing the machine?
● The quality of raw materials and key components and their manufacturing sources?
● Does the manufacturer use a deep manufacturing system (i.e., from the foundry to the finished machine, such as Hwacheon) or just assembly, or even use an OEM company?
● Are these machines mass produced? Or do they have focused production lines for specific needs and higher quality standards of production
The dimensions of a CNC lathe are generally defined by the chuck size and center distance.
Standard machines are usually less expensive than complex machines. The latter may be the same machine with additional options.
The price of the machine is also influenced by the different options chosen.
The addition of a Y-axis, additional motor power, spindle torque range, guideway system (linear ball or roller, box guideway), spindle coolant (CTS) system (30 or 70 bar), tool setting gauge, chip conveyor (standard or special aluminum), or spindle bore (especially if BB or BB+) will result in an increased cost for a standard machine.
Additional options such as special bearings, automatic tool changers (ATC) and hydraulic chucks will also affect the price of the machine.
Finally, the cost of shipping from the manufacturing location to the end user will increase the price of the machine. This can vary from country to country.
The size of the machine to be shipped will affect the type of packaging and shipping used (container or flat rack). This, in turn, will affect the price of the CNC lathe.
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