What is a Turning? An Overview of Turning Operations in CNC Machining(5 types of ceramics Joan)

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Turning is one of the most common machining processes used in manufacturing today. It involves rotating a workpiece while a cutting tool is fed against it to remove material. The workpiece is usually clamped in a chuck or collet on a lathe, which provides the rotational motion. The cutting tool moves linearly along one or more axes, engaging with the workpiece to cut away material.
Turning operations produce cylindrical shapes, which are extremely common in mechanical parts and components. In fact, it's estimated that up to 70% of all metal cutting operations are turning operations. From engine crankshafts to plumbing fixtures, turned parts are everywhere. Understanding what turning is and how it works is key for anyone involved in CNC machining or manufacturing.
What Equipment is Used for Turning?
The most essential piece of equipment for turning operations is the lathe. Lathes were originally manually operated, but today are almost always CNC (computer numerical control) machines. CNC lathes precisely control the movement and cutting actions via automated programming. Common lathe types include:
- Center lathes - The workpiece is held between two centers or combination chucks and rotated. The cutting tools move along the axis of the workpiece.
- Turret lathes - These have multiple cutting tools mounted on a turret that can be indexed to bring different tools into operation. Turret lathes are very efficient for high-volume production.
- Chucking lathes - The workpiece is securely clamped onto a chuck, which provides the turning motion. Chucking allows off-center and asymmetrical turning.
- Vertical lathes - On these lathes, the cutting tools are mounted vertically above the chuck. Vertical lathes are ideal for very large diameter turning operations.
Other essential turning equipment includes cutting tools, tool holders, coolant systems, and workholding devices like chucks and centers. The specific selection of tools and accessories depends on the material being cut and the features required. Rigidity is also critical for turning precision, so lathes must be very sturdily constructed.
What Are the Key Turning Operations?
While there are many different turning operations, these are some of the most common and important:
- Facing - The process of generating a flat surface perpendicular to the rotational axis of the workpiece. This is often the first operation done after mounting the raw material.
- Straight turning - Also known as cylindrical turning. This involves cutting away material around the circumference of a cylindrical or conical workpiece. The cutting tool feeds parallel to the rotational axis to remove material and achieve the desired diameter.
- Taper turning - Produces a tapered geometric shape on the workpiece. This requires the cutting tool to move at an angle to the rotational axis during feeds. The angle determines the rate of taper.
- Grooving - Involves cutting narrow channels or grooves into the workpiece surface. Used to create splines, threads, parting lines, and decorative patterns.
- Profiling - The cutting tool moves in two axes to machine complex non-cylindrical shapes. Common for contours, molded forms, and specialty custom parts.
- Boring - Enlarging or finishing an existing hole in the centerline of the workpiece. Requires a single-point cutting tool or boring head.
- Threading - Using a turning process to cut screw threads into a workpiece. Can be done externally or internally. Multiple passes are made using a threading tool.
- Parting/Cut off - Deep grooving operations used to cut a finished part completely free from its parent stock. Usually uses a specialized parting tool.
Many components require several different turning operations to achieve the full geometric forms and tolerance specifications. CNC programs can control the turret tool selection and coordinate the transitions between operations like facing, turning, grooving, and parting in one automated cycle.
Benefits of Turning in CNC Machining
There are many reasons why turning remains one of the most prevalent manufacturing processes:
- High material removal rates - Turning operations involve continuous cuts, allowing for faster machining. The production time savings over milling can be substantial.
- Excellent surface finishes - The nature of the turning process results in very fine surface finishes and accuracy. Minimal secondary polishing is required.
- Good dimensional precision and repeatability - Modern CNC lathes can repeatedly hold dimensional tolerances within 0.005 inches or less. This precision is critical for metal parts.
- Versatile workholding options - Workpieces can be securely clamped between centers, mounted in chucks, held in collets, or anchored using fixtures for rigidity during turning.
- Wide material suitability - Turning can be applied to almost any machinable material including metals, plastics, composites, and more. Different tool materials suit different workpiece materials.
- Minimal setup time - CNC turning centers allow loading raw stock, programming the toolpath, and starting the cycle with minimal setup time compared to other processes.
For round metal parts in particular, turning produces excellent results in terms of tolerance, surface finish, and cost-effectiveness. That is why it remains an indispensable manufacturing process, especially for lathe machining services and machine shops. Understanding the key turning concepts allows engineers and technicians to maximize the benefits of CNC turning operations. CNC Milling CNC Machining