Over the past few years, CNC machining technology has become the dominant technology in the metal forming industry because it offers highly precise and repeatable machining capabilities that go far beyond what can be achieved with traditional manual machining. Understanding the basics of CNC machining makes it clearer to decide which process to use to manufacture your parts. This article will explain everything about CNC turning in detail.
What is CNC Turning?
CNC turning is a machining process that involves the use of computer-controlled machines to create cylindrical parts. It is a subtype of CNC machining and is also known as computer numerical control turning. In this process, a rotating workpiece is held in a lathe, and cutting tools are used to remove material from the workpiece to achieve the desired shape and dimensions.
The process of CNC turning
CNC turning works by using a CNC turning machine to remove material from a rotating workpiece to create cylindrical parts with precision and accuracy.
1. Workpiece Setup: The process begins with securing the raw material, typically a metal or plastic cylindrical rod, in the lathe’s chuck or collet. The workpiece is mounted and centered to ensure proper alignment during machining.
2. CNC Programming: A computer program is created or generated using Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) software. This program contains specific instructions for the CNC machine to follow, including the toolpath, cutting speeds, feed rates, and other parameters.
3. Tool Selection: Based on the requirements of the design and material, suitable cutting tools are selected. These tools may include various types of inserts, drills, boring bars, and threading tools.
4. Machining Operations: Once the workpiece is set up and the CNC program is loaded into the machine, the turning process begins. The CNC machine rotates the workpiece at a controlled speed, while the cutting tool moves along the surface of the workpiece to remove material.
5. Tool Movements: The CNC system precisely controls the movements of the cutting tool in multiple axes (commonly X and Z axes for simple turning) as it engages with the rotating workpiece. This allows the tool to remove material and shape the workpiece according to the programmed design.
6. Continuous Machining: CNC turning is a continuous process, and the cutting tool moves smoothly along the workpiece, removing material layer by layer until the desired shape and dimensions are achieved.
7. Finishing: To achieve the required surface finish and dimensional accuracy, multiple passes with different cutting tools may be used. Finishing passes help to create smooth surfaces and tight tolerances.
8. Inspection and Quality Control: Once the machining process is complete, the finished part is removed from the lathe. It is then inspected to ensure it meets the required specifications and tolerances. Any necessary adjustments or post-processing may be done at this stage.
Parts suitable for CNC turning
Turning is a common machining method for many different types of parts manufacturing. The following are answers to the CNC turning parts suitable for turning according to the way they are categorized:
Cylindrical parts
– Shafts: such as transmission shafts, and drive shafts.
– Bushings: e.g. bearing bushings, bushings.
– Pipes and pipe fittings: e.g. pipe fittings, hydraulic pipes.
– Threaded rods: such as threaded rods and nuts.
Disc-shaped parts
– Nuts: such as screws, bolts.
– Flanges: e.g. bearing housing flanges, flange disks.
– Brake disk and clutch disk.
Ring-shaped parts
– Shaft rings: e.g. reducer shaft rings, coupling shaft rings.
– Bearing housing rings.
Tapered parts
– Conical: e.g. conical sleeves, conical shafts.
– Tapered gears.
Bump-shaped parts
– Cams: e.g. automobile engine cams, camshafts.
Complex shaped parts
– Rotationally symmetric parts: e.g. propellers, fan blades.
– Free-form surfaces: requiring turning in multiple axes.
Turning is widely used in the manufacturing industry, almost all need to have rotational symmetry or rotary axial shape of the parts can be processed by turning. Turning is a very flexible and efficient machining method that can be applied to a wide range of different materials, including metals, plastics and composites.
Advantages of CNC Turning
- Precision and Accuracy
CNC turning enables high levels of precision and accuracy in the production of cylindrical parts. The computer-controlled cutting tools can achieve tight tolerances and consistent results, ensuring that the finished parts meet exact specifications.
- Versatility
CNC turning can be applied to a wide range of materials, including metals, plastics, and even some composites. This versatility makes it suitable for manufacturing various components used in different industries.
- Efficiency and Productivity
Once the CNC program is set up, the machining process becomes highly automated. This reduces the need for manual intervention, leading to increased productivity and shorter lead times for producing parts.
- Complex Geometries
CNC turning can produce parts with intricate shapes and features, such as threads, grooves, and contoured surfaces. The ability to create complex geometries opens up new design possibilities for engineers and designers.
- Consistency and Reproducibility
CNC turning ensures consistent results across multiple production runs. Once a successful CNC program is established, it can be easily reproduced to manufacture identical parts with the same level of precision.
- Cost-Effectiveness
While initial setup and programming costs may be involved, CNC turning can be cost-effective for large-scale production due to its efficiency, reduced scrap rates, and consistent output.
The Differences Between CNC Milling and Turning
CNC milling and turning are two distinct machining processes used to create different types of parts and components. While both are computer numerical control (CNC) methods, they have distinct differences in their operations, capabilities, and applications. Here are the key differences between CNC milling and turning:
| Types | CNC turning | CNC milling |
| Workpiece motion | The workpiece rotates while the cutting tool remains stationary. | The workpiece is fixed and the cutting tool moves in several axes. |
| Geometries Produced | Cylindrical or rotationally symmetric parts such as cylinders, cones, and disks. | Complex shapes, pockets, slots, and intricate 3D features. |
| Surface finish | Smoother, more polished finish | High-quality surface finish, but may leave tool marks |
| Tools and Setup | Fewer tools and fast processing | Multiple tools, complex setup, slow time |
| Production Capabilities | Chemical Electrical Mechanical Thermal | Boring Drilling Facing Grooving Knurling Parting |
| Industries | 1.Woodworking 2.Electrical industry 3.Electrical discharge machining 4.Metal removing (in automotive or manufacturing) 5.Material fabrication | 1.Woodworking 2.Electrical industry 3.Electrical discharge machining 4.Metal removing (in automotive or manufacturing) 5.Material fabrication |
Conclusion
CNC turning is a machining process that involves the rotation of a workpiece while a cutting tool removes material to create a desired shape. Unlike conventional turning methods, CNC turning is automated and controlled by computer programs, allowing for unparalleled precision and repeatability.
