What is CNC Turning?(the melting point Laurel)
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- source:BAGANZ CNC Machining
How Does CNC Turning Work?
CNC turning utilizes programmable machine tools called CNC lathes. These lathes have a cutting tool mounted on a turret that can move in multiple axes, as directed by the CNC program. The workpiece is fixed in a chuck or between centers and rotates at high speeds while the cutting tool moves across its surface to remove material.
The CNC program controls all the movements and functions of the lathe, including:
- Spindle speed and direction
- Feed rate of the cutting tool
- Depth of cut
- Cutting tool selection
- Coolant application
- Turret indexing to change tools
By precisely controlling these variables, complex geometric features like grooves, chamfers, radii, and threads can be machined with accuracy up to 0.005mm. The flexibility of CNC allows fast changeover between different turning operations.
CNC turning follows these basic steps:
1. The workpiece material, usually bar stock or a casting, is loaded into the lathe chuck or collet. The chuck provides clamping force to hold the part securely during machining.
2. The dimensions of the raw material are manually measured and input into the CNC program. The program uses this to calculate how much material to remove.
3. The operator commands the CNC machine to begin executing the program code. All subsequent actions are fully automated.
4. As the part spins, the turret positions the cutting tool and begins removing material as specified in the program code. The tool follows precise paths across the face of the workpiece to contour the shape.
5. Cutting tools are automatically changed by the turret when needed. Common turning tools include round insert cutters, CCMT inserts, and boring bars. Tool offsets are compensated automatically.
6. When complete, the finished part is unchucked from the lathe and inspected to ensure it meets specifications. If needed, the CNC program can be adjusted and the part re-machined to fine tune the dimensions.
Advantages of CNC Turning
- Higher accuracy and repeatability compared to manual turning
- Ability to machine complex geometries not possible otherwise
- Quick changeover between operations
- Minimal setup time allows fast production of small batches
- Operator does not need extensive turning skills
- Safer than manual turning as the operator does not need to get too close during machining
- Reliable and consistent results part-to-part
Common CNC Turning Operations
Here are some of the common turning operations possible with CNC:
Facing - Machining the face of the part to a desired length. Performs OD (outside diameter) facing and ID (inside diameter) facing.
OD Turning - Also called longitudinal turning. Reduces the diameter of the workpiece to specific dimensions along its length.
Boring - Enlarges ID surfaces by plunging a single point cutting tool into the bore.
Drilling - Machines holes axially with a rotating drill bit.
Trepanning - Produces large diameter holes by using an annular cutter.
Grooving - Cuts grooves and undersized widths along the part OD or ID.
Parting/Cutoff - Cuts workpieces from bar stock to trim parts to length.
Threading - Cuts screw threads along the OD or ID. Single or multi-start threads possible.
Taper Turning - Machines angular tapers using a taper attachment.
Knurling - Squeezes material with special tooth cutters to produce roughened knurled patterns on the workpiece OD.
Contouring - Follows 2D or 3D profiles to machine complex irregular shapes dictated by the program coordinates.
CNC Turning Applications
The versatility of CNC turning makes it useful for manufacturing parts across many industries:
- Automotive - Engine valves, pistons, turbocharger housings, axles
- Aerospace - Bushings, nozzles, fittings, landing gear components
- Medical - Bone screws, joint replacement parts, surgical tools
- Firearms - Barrels, receivers, bolts, magazines
- Industrial - Valves, couplings, pulleys, drive shafts
- Consumer goods - Appliance housings, fasteners, connectors
For high volume production, CNC turning centers with live tooling, Y-axis, and multiple spindles can be used to further improve efficiency and minimize cycle times. This makes CNC turning ideal for both low and high volume manufacturing.
Getting Started with CNC Turning
To get started with CNC turning, here are some recommendations:
- Take training courses on CNC machining and programming to understand G-code and operation. CAM software courses are also very useful.
- Get access to a CNC lathe through your school, job, or a local maker space. Machine time is crucial.
- Learn the basics of cutting tools, speeds and feeds, machine setup, and measurement.
- Start with simple 2D turning operations like facing, OD turning, and drilling CNC Milling