CNC Turning Guide: Process, Operation, Advantages

CNC manufacturers use a combination of machining processes, including CNC turning, in their production process. CNC turning precisely removes material by rotating the workpiece in conjunction with the cutting tool, and mastering its basics is essential to improving production efficiency and product quality. This article will take you through the CNC turning process, the types of CNC turning operations, and the advantages of CNC turning.

What is CNC turning?

CNC turning is a high-precision and high-efficiency machining method that utilizes a computer control system to manage the lathe for rotational cutting of the workpiece precisely. This turning manufacturing process is ideal for creating cylindrical or rotationally symmetrical parts, and CNC turning machines can handle a wide variety of workpieces in terms of shape and size.

The ability to control turning operations with high accuracy makes CNC turning and lathing an essential process in industries that demand precision, such as aerospace, automotive, and medical.

CNC Lathes vs CNC Turning Centers

CNC Lathes

CNC lathes are primarily designed for basic turning operations, making them ideal for machining simple cylindrical parts. These machines are equipped with a rotating spindle that holds the workpiece, while a stationary tool performs various operations like cutting, drilling, and boring.

CNC lathing involves single-axis movement, typically around the Z-axis, although more advanced models may also allow limited radial movement along the X-axis. The CNC lathe machining process is straightforward and cost-effective, making it ideal for low to medium-volume production. CNC lathes are often used for parts such as shafts, bushings, and small cylinders.

In CNC lathes, a turret-style tool holder allows the use of multiple cutting tools, making it easier to perform different turning operations without the need for manual tool changes. This setup enhances both efficiency and precision during turning operations. Whether you are looking for basic turning or more complex, CNC lathe machining is an essential process that offers simplicity in setup and operation, especially for standard turning tasks.

CNC Turning Centers

CNC turning centers are more advanced than standard CNC lathes and offer greater flexibility for more complex turning machining tasks. CNC turning center machines are equipped with multiple axes—typically X, Y, and Z—allowing the machine to work on various sides of a part without the need to reposition it. This is particularly advantageous for parts that require turning, milling, drilling, and tapping, all in a single setup. CNC turning centers also often feature live tooling, which enables the tools to rotate and perform additional operations like milling and drilling, making them ideal for high-precision machining.

One of the key features of CNC turning centers is the sub-spindle, which allows for machining on the opposite side of the part without re-chucking. This capability significantly improves machining efficiency and reduces setup times. With greater automation, CNC turning centers are designed for higher production volumes and are commonly used in industries such as aerospace, automotive, and medical, where multiple operations need to be performed with high precision.

CNC Turning Process

Material preparation: Before CNC turning, you need to carefully prepare the material to be processed. This includes selecting the appropriate material type (such as aluminum alloy, stainless steel, titanium alloy, etc.) according to the product design requirements, and performing preliminary cutting, cleaning and drying of the material to ensure the cleanliness of the material surface and the accuracy of the size.

Equipment selection and debugging: Selecting a suitable CNC lathe is the key to ensuring machining quality. This requires consideration of factors such as the machine’s machining accuracy, maximum machining diameter, spindle speed, and power. During the debugging process, it is necessary to accurately adjust various machine parameters, such as tool position, cutting speed, feed rate, etc., and perform tool setting operations to ensure the accurate relative position between the tool and the workpiece.

Machining sequence planning: The processing sequence of CNC turning usually includes programming, program transmission, machine tool setting, trial cutting verification and formal machining. CAD/CAM software is used for programming to convert the design drawings into program codes that can be recognized by the machine tool, and then transmitted to the machine tool control system through the interface. Before formal processing, the correctness of the program is verified by trial cutting to ensure the rationality of the machining path and cutting parameters.

Quality inspection and correction: After processing, the workpiece needs to be strictly inspected and evaluated for quality. Use measuring tools or testing equipment to measure the size, shape and position tolerance, surface roughness, etc. of the workpiece to ensure that the product meets the design requirements. If unqualified products are found, the reasons must be analyzed in time and corresponding corrective measures must be taken.

Types of CNC Lathes

As the core machine tool of the turning process, the CNC lathe has many types, each type is designed for specific machining needs. The following are four common types of CNC lathes, which play a key role in various processing projects:

Horizontal CNC Lathe:

Horizontal CNC lathes are one of the most widely used types of lathes in the industrial field. This type of lathe is not only good at efficient turning operations, but also has compound processing capabilities such as boring. Through pre-programmed computer instructions, horizontal CNC lathes can automatically complete complex processing tasks, greatly improving production efficiency and processing accuracy.

Vertical CNC Lathe:

Unlike horizontal CNC lathes, vertical CNC lathes have made innovations in the way workpieces are fixed. They use a vertical positioning method to clamp the workpiece material from the bottom. This design allows vertical CNC lathes to operate flexibly in environments with limited space and is particularly suitable for production scenarios with certain restrictions on the height of the workpiece. In addition, vertical CNC lathes also show excellent performance when processing heavy workpieces, which can ensure the stability and accuracy of the processing process.

Horizontal Turning Center:

The horizontal turning center is a multifunctional closed equipment that integrates turning, drilling and milling. Its uniqueness lies in that the tool is installed on the top and cuts into the rotating workpiece horizontally during operation. This layout not only optimizes the processing path, but also uses gravity to assist in chip removal, further improving processing efficiency and workpiece surface quality.

Vertical Turning Center:

The vertical turning center is a perfect combination of the horizontal turning center and CNC milling machine technology. It innovatively designs the rotating chuck close to the ground. This low center of gravity layout makes the equipment more stable and reliable when processing complex and large workpieces. The vertical turning center not only inherits the various processing capabilities of the turning center, but also improves the processing efficiency and accuracy of large and special-shaped workpieces by optimizing the structural design and processing strategy.

What Shapes of Parts Require Turning?

Cylindrical Parts:

Cylindrical shapes are one of the most common shapes in lathe machining, such as shafts, pins, threads, gears, flanges, hubs, etc. These parts usually have rotational symmetry and are suitable for mass production by turning.

Conical Parts:

Conical parts are usually used in transmission devices, such as transmission shafts, clutches, duty shafts, etc. In lathe processing, conical parts often use tool heads tilted at different angles to achieve the desired tilting effect.

Prismatic Parts:

Prismatic parts refer to parts with multiple planes, such as polyhedrons, cylindrical prisms, triangular pyramids, etc. When machining prismatic parts on a lathe, it is necessary to pay attention to maintaining the angles and shapes between the planes to avoid excessive errors and asymmetrical effects.

Curved Parts:

Curved parts are usually used in the manufacture of automotive parts and mechanical parts, such as curved shafts, wheels, cams, bushings, etc. When machining curved parts on a lathe, there are many process factors that need to be considered, such as cutting angle, tool edge angle, cutting speed, feed speed, etc. Only through skilled operation and technical experience can high-quality curved parts be obtained.

Advantages of CNC Turning

High Precision and Quality:

High precision: CNC turning can achieve very high machining accuracy, usually within a few microns, thanks to the tool path and cutting parameters under precise computer control.

High quality: Due to the stability and precision of the machining process, CNC turning can produce parts with high surface quality and high dimensional accuracy, meeting the high-precision requirements of industries such as aerospace and medical devices.

Complex Parts Processing Capabilities:

Multi-process machining: CNC turning can process parts that need to be processed in multiple processes after one clamping and positioning, reducing the number of times the workpiece is repositioned and clamped, and improving processing efficiency.

Complex shape processing: It can process parts with particularly complex contour shapes or difficult-to-control dimensions, such as mold parts, shell parts, and complex curve parts described by mathematical models and three-dimensional space surface parts.

Automation and Efficiency:

High degree of automation: During the CNC turning process, the operator only needs to write programs and monitor the operation of the machine tool, without directly participating in the processing process, which reduces labor costs and improves production efficiency.

High production efficiency: CNC machine tools can process at higher speeds and feed rates while reducing human errors and downtime, further improving processing efficiency.

Flexibility and Adaptability:

Strong flexibility: CNC turning processing has strong adaptability and can flexibly respond to the processing needs of parts of different shapes and sizes.

Wide range of applications: It can not only process parts that are difficult to process with ordinary lathes, but also process high-precision and high-difficulty parts, such as small-mouthed and large-bellied internal surface parts.

Types of CNC Turning Operations

There are many types of CNC turning operations, which are mainly classified according to factors such as processing requirements, workpiece shape and processing accuracy. The following are some common types of CNC turning operations:

Linear Turning:

As the most basic turning operation, linear turning involves the tool cutting the workpiece along a straight path. It is particularly suitable for machining parts with simple shapes such as cylindrical and flat surfaces. The linear turning process is stable and easy to control, which can ensure the dimensional accuracy and surface quality of the parts.

Taper Turning:

Taper turning is a process in which the tool cuts along a certain angled path while the workpiece is rotating, thereby processing a conical or frustum-shaped part with a taper. This processing method is widely used in occasions such as transmission shafts and connectors that require taper fit, which can ensure close fit and accurate transmission between parts.

Profile Turning:

Profiling is a machining method that imitates a specific shape or contour so that the tool cuts the corresponding shape or contour on the workpiece. It is particularly suitable for machining parts with complex shapes or irregular contours, such as cams, molds, etc. Profiling can ensure the shape accuracy and surface quality of the parts and meet the needs of high-precision machining.

External Grooving:

External grooving is to cut a groove of a certain width and depth on the external surface of the workpiece, which is often used to process keyways, oil grooves, etc. This machining method can enhance the functionality and performance of parts, such as improving the assembly accuracy, lubrication effect and load-bearing capacity of parts. The machining process of external grooving is relatively simple, but it requires the tool and machine tool to have high precision and stability.

Boring:

Although boring mainly belongs to the category of hole processing, it is also one of the common operations in CNC turning. It uses a boring tool to cut the inside of the workpiece to expand the hole diameter or improve the surface quality of the hole. Boring is particularly suitable for processing high-precision, large-diameter holes and occasions where the coaxiality between holes needs to be ensured. Through boring machining, it can be ensured that the dimensional accuracy, shape accuracy and surface roughness of the hole meet the design requirements.

Hard Turning:

Hard turning is the turning process of materials with higher hardness, usually after heat treatment of the workpiece. This processing method aims to replace or limit traditional grinding operations and improve processing efficiency and machining accuracy. Hard turning is particularly suitable for parts that require high roundness accuracy and surface roughness, such as gears, injection pump components, etc. By optimizing tool materials, cutting parameters and machine tool performance, hard turning can achieve efficient and high-precision machining results.

Compound Turning:

Compound turning is a machining method that completes multiple machining processes in one clamping, such as turning, drilling, milling, etc. This machining method can significantly improve machining efficiency and machining accuracy, and reduce the number of workpiece repositioning and clamping. Compound turning is particularly suitable for machining complex parts and batch production occasions, which can reduce production costs, improve production efficiency and product quality. By integrating multiple machining processes in one clamping, compound turning realizes the continuity and automation of the machining process.

Materials Suitable for CNC Turning

Metal Materials:

Aluminum Alloy

Aluminum alloy is widely used in aerospace, automobile manufacturing, electronics and construction due to its lightweight, high strength, strong corrosion-resistance, good conductivity and non-magnetic properties. It is suitable for making various precision parts and components, such as engine parts, body structural parts, electronic equipment housings, etc.

Stainless Steel

Stainless steel is known for its high strength, high ductility, wear resistance and excellent corrosion resistance, and is commonly used in industries such as medical, food, beverage, and aerospace. It is suitable for making parts that require high strength and corrosion resistance, such as surgical instruments, food machinery parts, and chemical equipment accessories.

Steel

Mild steel: easy to process, often used to make mechanical parts, steel bars, chains, etc.

Hard steel: has higher hardness and strength, suitable for occasions requiring higher wear resistance and strength, such as knives, molds, bearings, etc.

Copper and Copper Alloys

Brass is often used in the fields of precision instrument manufacturing, ship parts production, musical instruments and craft products due to its ductility, wear resistance, corrosion resistance and good conductivity. It is suitable for making gears, bearings, conductive parts and decorations.

Titanium Alloy

Titanium alloys have an important position in aerospace, shipbuilding and other fields due to their low density, high strength, good corrosion resistance and high-temperature resistance. They are suitable for making high-demand parts and structures, such as aircraft engine components and spacecraft structures.

Non-metallic materials:

Engineering Plastics

Engineering plastics such as ABS, PC, POM, etc. have excellent physical and mechanical properties and are easy to process. They are widely used in the fields of electronics, automobile manufacturing, medical equipment, etc., and are suitable for making housings, parts and structural parts.

Nylon

Nylon is often used to make mechanical parts such as gears, bearings, and transmission components due to its wear resistance, oil resistance, chemical corrosion resistance, and high strength.

In Conclusion

CNC turning technology is an important part of the manufacturing industry and is widely used in various fields. It is highly versatile, can accurately control dimensions, and is suitable for large-scale production. Many CNC manufacturers use CNC machine tools, which are automated through pre-programmed software, making the production process more efficient, fast, and accurate.

As experts in CNC machined part manufacturing, VMT provides high-quality custom milling services to meet your specific precision component needs. With advanced CNC machining equipment and rich manufacturing experience, we can perform precision processing according to your requirements and drawings. Whether it’s complex geometries, high-precision tolerance requirements, or special material selections, VMT can provide custom solutions.