Introduction to CNC Turning(fibre laser machines Bruce)

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CNC (Computer Numerical Control) turning is a machining process used to create rotational, symmetrical parts by rotating a workpiece while a cutting tool moves linearly to remove material. CNC turning is performed on a lathe that is controlled by a computer. This automated process enables high precision and productivity unmatched by manual turning. CNC turning is widely used across many industries such as automotive, aerospace, medical, and more.
How CNC Turning Works
CNC turning relies on programmed instructions from CAM (Computer Aided Manufacturing) software. These instructions guide the movements of the cutting tool while the workpiece rotates. Here are the main components and functions that enable CNC turning:
- CNC Lathe: The machining center where turning operations are performed. CNC lathes have a headstock and tailstock between which the workpiece is mounted. The headstock rotates the workpiece while the tailstock provides stability.
- Cutting Tool: Made of hard materials like carbide, the cutting tool removes material from the workpiece by moving linearly while the part rotates. Common tool geometries are round inserts and square inserts.
- Tool Turret: This is an indexable tool magazine that can hold multiple cutting tools. It allows efficient tool changes for different turning operations.
- Program: The program guides all machine movements and functions. It is written in G-code, which converts CAD model dimensions into coordinate points and toolpaths.
- Controller: This computer controls the machine tool. It reads the G-code program and drives machine components like the spindle and turret.
The basic CNC turning sequence involves four steps:
1. The workpiece is loaded onto the CNC lathe and clamped between the headstock and tailstock.
2. The controller executes the programmed code. The headstock chuck rotates the workpiece while the tool turret positions a cutting tool.
3. The cutting tool feeds towards the part along the programmed path, removing material as the part rotates.
4. When finished, the machine ejects the completed part and a new workpiece is loaded to repeat the process.
CNC Turning Capabilities
The versatility of CNC turning allows production of a wide variety of precision parts. Here are some key capabilities:
- Cylindrical Shapes: CNC lathes specialize in machining parts with cylindrical symmetry, including round, tube-like, and curved shapes.
- Dimensional Accuracy: Programmed coordinates direct the cutting tool to machine features to tight tolerances of 0.001 inches or less.
- Surface Finishes: Adaptive toolpaths and polished cutting tools impart fine surface finishes to products. Finishes to 8 microinches are possible.
- Complex Geometries: Today's advanced CNC lathes can produce intricate contours, tapers, grooves, and threaded features.
- Automated Production: CNC turning enables unmanned production of high volumes of parts, maximizing productivity around the clock.
Common CNC Turned Parts
CNC turning produces parts found in countless industries. Here are some examples:
- Engine and Transmission Components: Crankshafts, camshafts, pistons, gears, valves and more are machined by CNC turning with great precision.
- Orthopedic Implants: Hip, knee, and spinal implants feature CNC turned spherical and cylindrical shapes. Biocompatible metals are used.
- Nozzles: Turning produces nozzles with calibrated orifices for fluid control in industries like aerospace, chemical processing, and more.
- Connecting Rods: These essential engine components are turned to achieve balanced weighting and precise fit.
- Pump Housings: CNC turning machines pump components from metals and plastics to optimal dimensions.
- Rollers: Industrial rollers for conveying, printing, and other uses are produced by CNC lathes for durability.

CNC Turning Processes
To create these turned parts, certain material-removal processes are utilized. Common CNC turning processes include:
- Rough Turning: Also called roughing, this first pass removes excess material efficiently with a large depth of cut.
- Finish Turning: The finishing pass uses a smaller cut depth for higher precision and surface finish. Slow speeds and feeds are used.
- Grooving: Narrow, straight cuts interior or exterior to the part create grooves for seals, fasteners, and parting off.
- Face Turning: Turning the front face of a part creates a flat reference surface perpendicular to the rotational axis.
- Boring: An internal boring bar machines the inner diameter and holes with great accuracy.
- Threading: The CNC lathe can cut highly precise external and internal threads for fastening or lead screws.
- Drilling: Accurate center drilling and hole making is possible via CNC turning operations.
- Taper Turning: By offsetting the tailstock, inclined tapers can be produced. Form tools also create tapers.
- Undercutting: An inside contouring tool, like a dovetail cutter, machines complex undercut profiles not possible otherwise.
CNC Turning Best Practices
Following proper practices in CNC turning leads to optimally machined parts. Here are some top tips:
- Select suitable material: Choose materials like aluminum, steel, titanium, and plastics that are easy to machine. Avoid exotic alloys.
- Design for manufacturability: Avoid overly complex geometries. Design parts to minimize machining operations.
- Utilize proper cutting tools: Use sharp tools with correct geometries and coatings to maximize tool life.
- Apply proper feeds and speeds: These parameters must suit the material, tooling, and operations performed.
- Use fixtures for support: Tailstock, steadies, and other fixtures provide support during turning operations.
- Employ coolant for lubrication: Coolant/lubricant keeps cutting tools and material cool and flushed of chips.
- Program efficient toolpaths: Optimize the tool movements in CNC code to minimize machining time.
- Validate programs: Verify all code before machining to catch programming errors. Simulation software can help.
- Inspect parts frequently: Check dimensions and tolerances at multiple stages to ensure quality standards.
By following these best practices, manufacturers can achieve exceptional results from CNC turning processes. The automated precision of CNC turning makes it a go-to machining process for high volume production across countless industries. CNC Milling CNC Machining