What is a Turning?(machining metal Morton)

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  • source:YESCOM CNC Machining
A turning is a machining operation used to reduce the diameter of a cylindrical workpiece or to create a specific geometric feature on the outside or inside diameter of a workpiece. Turning is performed on a lathe, which spins the workpiece at high speeds while a cutting tool is fed into it to remove material. This makes turning one of the most fundamental and common machining processes in manufacturing.
How Does Turning Work?
The turning process utilizes a cutting tool, typically made from high speed steel, carbide, ceramic or cubic boron nitride, that is held rigidly in a tool holder. The tool holder is mounted to the cross-slide of the lathe, which moves it perpendicular to the axis of the rotating workpiece. The cutting action occurs at the tip of the cutting tool, which has been ground to precise angles and geometries optimized for various materials and operations.
As the workpiece rotates, the cutting tool is fed either longitudinally along or into the outside or inside diameter of the workpiece. The relative motion between the tool and workpiece results in thin chips being sheared off along a continuous curl. The depth and rate of cut determine the amount of material removed. Coolant is often applied to control chip formation and temperature. The basic turning process can produce cylindrical shapes of various diameters, shoulders, grooves, tapers and contoured profiles.
More complex lathe work, such as threading, boring, drilling or reaming can be performed during turning operations. Precision turning allows for fine surface finishes and tight tolerances to be achieved. The high material removal rates possible make turning very efficient for reducing diameters and faces. It is ideal for producing rotationally symmetric features needed on many components like shafts, rollers, bolts, bearings and fasteners.
Turning Operations:
- Facing - machining the end face of a cylinder
- Straight turning - reducing the diameter of a cylinder
- Taper turning - producing a tapered diameter
- Profiling - machining complex contours and shapes
- Grooving/parting - cutting deep internal/external grooves
- Boring - enlarging and smoothing internal diameters
- Threading - cutting screw threads, both internal and external
- Form turning - using a form tool to machine complex profiles
- Chamfering - beveling sharp edges
- Undercutting - recessing a diameter next to a shoulder
- Eccentric turning - machining off-center profiles
- Copy turning - duplicating a form from a template
Advantages of Turning:
- Highly efficient stock removal for round shapes
- Excellent dimensional accuracy and surface finish
- Wide range of workpiece sizes accommodated
- Variety of operations possible on a single machine
- Fast setup time between jobs
- Minimal stock wasted compared to milling
- No special workholding required for external turning
- Relatively low forces and power requirements
Turning Materials:
Almost all machinable materials can be successfully turned, including:
- Aluminum and its alloys
- Steel alloys - low, medium, high carbon
- Stainless steel
- Tool steel
- Nickel alloys
- Titanium alloys
- Cobalt alloys
- Precious metals - gold, silver, platinum
- Plastics - HDPE, PTFE, acetal, nylon
- Wood
- Composites
- Ceramics - alumina, zirconia

Turning Applications:
Turning is applied across practically every industry since cylindrical features and holes are required on almost any mechanical component. Typical applications include:
- Automotive - shafts, spindles, gears, pulleys, bushings
- Aerospace - complex titanium and nickel alloy engine parts
- Energy - precision turned pump housings, valves, compressors
- Medical - surgical instruments, implants, prosthetics
- Military/Defense - missile, artillery, and ordnance components
- Firearms - rifle, pistol barrels and actions
- Marine - drive shafts, fittings, propellers
- Oil/Gas - drill bits, casing, pipelines, valves, pumps
- Automation - robot joints, actuators, shafts
- Fasteners - screws, bolts, nuts, rivets
- Construction/Mining - augers, excavators, cranes
Turning Terminology:
It is helpful to understand some common terminology used to describe parameters in turning:
- Workpiece - The raw material part being machined
- Chip - The small pieces of material sheared off by the cutting tool
- Depth of cut - The radial distance cutting into the workpiece
- Feed Rate - The speed at which the tool advances along or into the work
- Spindle speed - Rotational speed of the lathe spindle and workpiece
- Coolant - Fluid used to cool the work area and remove chips
- Face - The end surface of a cylinder
- Shoulder - A step in the diameter of a cylindrical workpiece
- Undercut - A reduced diameter near a shoulder
- Chatter - Vibration between the tool and workpiece
- Dwell - When the cutting tool pauses movement
- Plunge - Rapid radial movement of the tool into the work
- Roughing - Initial bulk material removal
- Finishing - Final pass to achieve good finish and tolerance
Turning Safety:
There are some important safety guidelines to follow when turning:
- Always wear safety glasses to protect eyes from flying chips
- Ensure all guards are in place around the headstock, chuck, and tailstock
- Use proper extraction and filtration to remove metal chips and fumes
- Clamp down workpieces securely in chucks or collet fixtures
- Keep a safe distance from rotating parts - no loose clothing or jewelry
- Never adjust the machine with power on and moving parts
- Select the right feed rate and depth to avoid tool chatter
- Use properly sharpened tools designed for the material and operation
- Let the spindle come to a complete stop before changing tools
- Keep the work area clean and free of oil spills or chips
- Stay focused and do not get distracted while operating the machine
In closing, turning is arguably the most versatile and widely-used machining process, allowing for precise round shapes to be created. Understanding the basic turning operations opens up a world of manufacturing possibilities. With the right setup and safety practices, turning can shape components that power our modern world. CNC Milling CNC Machining