What is CNC Turning?(precision casting parts Ansel)

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CNC turning is a machining process used to create rotational parts by removing material from a cylindrical workpiece. The turning process is performed on a computer numerical control (CNC) lathe that can accurately and efficiently automate the turning of parts.
CNC turning first emerged in the 1940s and 1950s and allowed for more precision and consistency compared to manual lathes. Modern CNC turning centers are equipped with electronic controls that direct the machine tool and allow for advanced programming capabilities.
How does CNC Turning Work?
CNC turning works by using programmable machine movements to rotate and cut material from the workpiece. The workpiece is secured in the spindle of the lathe and rotated at varying speeds while a single pointed cutting tool removes material. By precisely controlling the movements and speeds, complex geometric shapes can be produced.
The basic CNC turning process involves three primary movements:
- Rotation of the Workpiece: The cylindrical workpiece is held and rotated by the spindle at a specified speed. Faster speeds are used for materials like aluminum while slower speeds are optimal for harder materials like steel. The rotational speed is programmed based on the material and desired finish.
- Infeed of Cutting Tool: The cutting tool moves linearly across the rotating workpiece to remove material. This inward movement is known as the infeed and the depth is programmed based on the amount of material desired to be removed.
- Transverse Movement: The cutting tool can also move perpendicularly parallel to the axis of the workpiece to produce the required diameter. This transverse movement of the tool along the x-axis creates the outside diameter dimension.
By precisely controlling these three movements, the necessary turning operations can be performed via CNC programming. The program specifies the spindle speed, feed rate, depth of cut, and orientation of the tool to create the required part geometry.
What are the Benefits of CNC Turning?
CNC turning offers several benefits and advantages over manual turning:
- Consistency: CNC automation ensures each part is turned exactly the same. This level of consistency is impossible to achieve with manual machining.
- Accuracy: Modern CNCs are capable of minute movements to produce parts within tight tolerances of ±0.005 inches or less. Complex geometries can be programmed for maximum accuracy.
- Complexity: Intricate part geometries with contours, tapers, grooves, and radii can be produced using CNCs that are otherwise challenging or unfeasible with manual methods.
- Efficiency: CNC turning produces parts faster and with less manual labor compared to manual turning. Multiple parts can be produced in continuous runs.
- Reduced Waste: Automation minimizes chances of errors and improves material usage. Less scrap material is produced compared to manual methods.
- Improved Surface Finishes: Excellent surface finishes and fine surface details can be achieved by optimizing the speeds, feeds, and tool paths.
- Operator Safety: The operator performs the machining process away from the machine operations inside a control room. This enhances safety and reduces accidents.
Overall, CNC turning offers substantially higher precision, efficiency, flexibility, and consistency compared to manual turning techniques.
CNC Turning Operations
Common turning operations that can be performed on a CNC lathe include:
- Facing: A facing operation involves moving the tool at right angles to the workpiece axis to produce a flat end face. This is done before further machining.
- Straight Turning: Removes material to create the outside diameter by feeding the tool parallel to the workpiece axis. Creates a straight cylindrical surface.
- Taper Turning: The tool feeds at an angle to the workpiece axis to generate a tapered diameter. Common for tool bits and gages.
- Profiling: Complex external profiles are produced by closely controlling the transverse movements and position of the tool.
- Grooving: Turning a groove by feeding the tool perpendicular to the surface. Useful for splines, threads, and recessing.
- Parting: A parting tool with a sharpened top edge is fed radially inwards to cut off the workpiece into two parts.
- Boring: An internal boring bar machines holes or enlarge existing holes along the axis of the workpiece.
- Threading: Threading tools can cut external and internal threads in the part. Requires precise coordination of rotation, tool movement, and offsets.
- Drilling/Spotting: Live tooling attachments can drill holes perpendicularly into the workpiece or produce spot faces.
- Knurling: A knurling tool creates a pattern of indentations on the workpiece surface to provide grip. Requires fine transverse movements.
By selecting the right tools and combining different operations, intricate turned parts can be manufactured through creative CNC programming.
CNC Turning Tools
A variety of specialized cutting tools are used in CNC turning to optimize different operations:
- Turning Tool Holder: This clamp holds and positions insert tool bits at precise angles. Carbide inserts with special geometries and coatings provide cutting ability.
- Boring Bars: Long bars with replaceable carbide inserts used to enlarge internal diameters. Available in multiple styles such as straight, tipped, and on-center.
- Threading Tools: Carbide inserts and high speed steel inserts that generate both internal and external threads. Use specialized geometries and Chipbreakers.
- Grooving Tools: Rigid tools with inserts that can cut various width grooves. Insert shapes include round, square, triangular.
- Parting & Cut Off Tools: Designed to part workpieces by cutting radially inwards. Sharpened blades and unique Chipbreaker geometries.
- Form Tools: Made as per profile of part geometry to produce specific complex external shapes via form turning. HSS and carbide.
- Drills: Live tooling attachments allow drilling holes perpendicular to the spindle axis using center and other industrial drills.
- Knurling Tools: Roll knurling or cut knurling tools that provide enlarged teeth for impressing/indenting work surfaces.
The wide range of tooling caters to all turning operations needed in part production. Tool holders accommodate indexable insert designs for quick changes. Proper tool selection coupled with optimal cutting parameters result in superior turning performance, efficiency, and part finish.
CNC Turning Machine Configurations
CNC turning centers are available in a variety of configurations for handling different workpiece sizes and turning requirements:
- Vertical Turning Lathe (VTL): The workpiece rotates vertically on the spindle with the cutter mounted on the horizontal ram. Handles large heavy parts.
- Horizontal Turning Machine: Most common configuration with horizontal bed and horizontal spindle. Used for medium batch production.
- Precision Turning Machine: Advanced C axis control and live tooling to turn complex shapes. Ideal for precision parts in smaller quantities.
- Multi-Spindle Turning Center: Multiple rotating spindles allow completing multiple operations simultaneously. High production.
- Twin Spindle Lathe: Has two spindles that allow simultaneous turning of both ends of the workpiece. Reduces cycle times.
- Chucking Machine: Equipped with a 3,4,or 6 jaw chuck to hold small workpieces for high precision turning. Used to machine small parts like fasteners, bushings etc.
- Automats: Special purpose precision production machines to mass produce parts like shafts. Feature automated loading/unloading of bars.
The needs of the application determine the best-suited CNC turning machine design for optimized rigidity, precision, productivity, and quick changeover between batches.
Programming CNC Turning Machines
Dedicated offline programming software allows efficient CNC turning programming from a separate computer:
- CAD Models: The program starts with 3D CAD model or solid model of the finished part. This provides required part geometry details.
- Toolpath Generation: Software simulates material removal by different tools and generates optimized toolpaths. The toolpath visualizes the sequence of cuts.

- G-Code Creation: CAM software post-processes the toolpaths to convert them into G-code programs containing the coordinates, speeds, and cycle instructions.
- Machine Simulation: The program is graphically simulated to visually verify the entire machining sequence on a virtual CNC machine. Errors can be detected.
- Program Transfer: The G-code program is then transferred to the CNC turning center through Ethernet cables, USB drive, or other methods.
- Machine Setup: The operator sets up the blank workpiece, fixtures, and tools on the machine as required by the program.
- First Article Inspection: The first part is carefully inspected to ensure it matches the specifications before full production run.
Efficient offline programming software facilitates quick turnaround of CNC turning jobs from concept to finished parts.
In Summary, CNC turning is a versatile turning process suitable for mass production or small-batch complex parts. The automated CNC machine tools can quickly and accurately turn cylindrical parts complete with special features. With competent programming and setup, CNC turning delivers high productivity along with enhanced quality at lower costs compared to manual methods. Continued developments in cutting tools and machine capabilities will further improve the advantages of CNC turning as a value-adding manufacturing process. CNC Milling CNC Machining