What is a Turning Operation in CNC Machining?(what are torsion snap joints Augus)

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Turning is one of the most common machining processes performed on a lathe or turning center in manufacturing industries. It involves rotating the workpiece while a cutting tool is fed into it to remove material and create the desired shape. Turning produces cylindrical parts that have rotational symmetry. With computer numerical control (CNC) machines, turning operations can be automated for high precision and productivity.
In this article, we will look at:
- What is turning and how it works
- Different types of turning operations
- The turning process step-by-step
- Advantages of CNC turning
- Common applications of turning
What is Turning?
Turning is a form of machining that uses a cutting tool to remove material from the exterior surface of a rotating cylindrical workpiece. The workpiece is held and rotated by the spindle of the lathe while the cutting tool is fed against it along its axis or periphery to cut away material. This removes unwanted outer diameters and faces the part to precise dimensions and surface finish requirements.
Turning uses a single point cutting tool with defined geometry, usually made of carbide or high speed steel. The cutting edges are ground to optimize cutting performance for the material being machined. The cutting tool is held rigidly by the tool post and can be fed towards the workpiece by hand or automatically under CNC control.
The speed of the rotating workpiece, depth of cut, feed rate of the tool, and cutting tool specifications determine the interaction between the tool tip and workpiece to remove material efficiently. Coolant is used to keep the temperature down and wash away chips.
Types of Turning Operations
There are several common turning operations that can be performed on dedicated lathes or multi-axis CNC turning centers.
- Outside diameter (OD) turning - The most basic operation that reduces the diameter of a cylindrical workpiece by removing material from the outer surface. The workpiece is fed past the cutting tool tip along its axis.
- Facing - Used to create a flat surface on the end of a cylinder. The tool cuts perpendicularly into the rotating end of the workpiece.
- Boring - Enlarges the inner diameter of holes by feeding the tool radially inward against the hole's inner surface.
- Grooving - Cuts narrow, straight axial grooves into the workpiece. Useful for parting off finished parts.
- Threading - Cuts screw threads externally or internally using shaped cutters and synchronized axis movement.
- Drilling - Can machine straight holes axially into the workpiece using rotating drill bits.
- Taper turning - Shapes conical geometries by tilting the tool at an angle to the workpiece axis.
The Turning Process Step-by-Step
Though setups vary based on part geometry, the general turning process follows a common sequence of steps:
1. The workpiece material is cut to the required length and mounted firmly on one end of the lathe spindle. Common workholding methods include chucks, collets, and fixtures.
2. The tool turret indexes to bring the right cutting tool into position. The tool height is set relative to the workpiece centerline.
3. Coolant starts flowing over the cutting area to lubricate, cool, and flush away chips.
4. The spindle rotates the work at an optimal cutting speed while the tool engages the surface. The feed rate determines how quickly the tool moves across the work along its axis.
5. The first turning pass machines away the bulk of material. Subsequent finishing passes refine the form, dimensions, and surface finish.
6. Steps are repeated with other tools to complete all required turning features and operations. Multiple parts can be batched on certain CNC lathes.
7. Completed parts are removed and new workpieces are loaded to start the next cycle.
Advantages of CNC Turning
While basic manual lathes rely on the operator’s skill, CNC turning centers offer many advantages:
- High precision and repeatability from automated programming and control. Complex geometries can be machined.
- Faster cycle times improve productivity due to optimized tool paths and no manual loading/unloading.
- Operator involvement is reduced to setup and program management rather than hand turning expertise.
- Flexible production from easy program changes to accommodate design revisions or new parts.
- Multitasking capabilities on certain CNC lathes allow milling, drilling, and other operations to be performed.
- Intelligent monitoring prevents crashes and minimizes human errors.
- Advanced software makes programming easy even for complex parts.
Turning Applications
Turning is utilized across many industries to produce a variety of rotational parts including:
- Automotive - Engine blocks, brake drums, drive shafts, pulleys
- Aerospace - Nose cones, shafts, discs, fasteners
- Medical - Bone screws, hip joint implants, surgical power tool casings
- Industrial - Pump housings, valve bodies, compressor rotors
- Consumer - Bottle stoppers, candle holders, salt/pepper grinders
From high volume fastener manufacturing to large scale steam turbine components, CNC turning covers a vast range of part sizes and production volumes. Continued advancement in turning technology and machinery is enhancing efficiency across manufacturing. CNC Milling