What is CNC Turning?(lightweight strong material Vera)
- source:MAJA CNC Machining
CNC turning has revolutionized the production of rotational parts like shafts, rods, tubes and discs. It enables fast, high-quality results for both simple and complex part geometries. This article provides an in-depth look at CNC turning, including how it works, the main components, types of operations, advantages and disadvantages.
How CNC Turning Works
On a CNC lathe, the workpiece is securely clamped on one end of the machine spindle. The spindle rotates the part at high speeds while a cutting tool approaches it to remove material. The cutting tool is held by the tool turret and can move across multiple axes to access all part surfaces.
The motion of the cutting tool is precisely controlled by the CNC system. Programmed commands from CAM (computer-aided manufacturing) software guide the toolpath. Operators create the machining programs on a CAD/CAM workstation and then transfer them to the CNC control.
The key CNC turning steps are:
- The operator clamps the workpiece onto the rotating spindle.
- The desired tool is selected and positioned by the tool turret.
- The CNC program runs, spinning the part and moving the cutter along accurate paths.
- Machining cycles repeat until the part is complete.
- The finished part is unloaded and a new workpiece is loaded to start the next production cycle.
CNC lathes contain several important components that work together to cut material from parts accurately and efficiently:
- Spindle – The main rotating axis that turns the work at high speeds for cutting. Geared headstock spindles offer the widest speed ranges.
- Chuck – Grips and locates the workpiece onto the spindle nose. Popular types are 3-jaw chucks and collet chucks.
- Tool turret – Holds multiple cutting tools and indexes them into position for machining operations. May have various numbers of tool stations.
- Tool holders – Secure cutting tools rigidly in the turret for precise machining. Common tool holders include VDI, CAT, BT and HSK styles.
- Tailstock – Located opposite the headstock and allows supporting the part with a center or chuck.
- Tool changer – Automatically changes tools in the turret per the CNC program for flexible unattended production.
- Guideways – Provide precision linear motion to move the turret and tailstock accurately along set axes.
- Chip conveyor – Removes swarf and chips from the machining area for uninterrupted cutting.
- Coolant system – Floods cutting areas with lubricating fluids to control temperatures and chip formation.
- Control panel – Allows operators to supervise the process and interface with the machine settings.
- Enclosure – Full enclosures contain heat, noise and hazards for improved working conditions.
Types of Operations
CNC turning centers can perform a wide range of turning, facing, boring and grooving operations. Here are some of the most common CNC turning process capabilities:
- Facing – Machines surfaces perpendicular to the spindle axis for squaring part ends.
- OD (Outside Diameter) turning – The fundamental operation for machining external diameters down to specific sizes.
- ID (Inside Diameter) boring – Enlarges existing inside diameters or creates internal bores in parts.
- Drilling – Axial hole making operation done with twist drills or indexable drills.
- Taper turning – Machines external or internal tapers with controlled angles.
- Grooving – Cuts grooves, threads and decorative patterns into the part surface.
- Cut-off – Parts completed parts from barstock by cutting through entirely.
- Threading – Cuts screw threads accurately using single point or thread milling tools.
- Form turning – Complex shapes are produced using form tools and C axis contouring capabilities.
- Knurling – Squeezes decorative slip-resistant patterns onto parts using a knurling tool.
More advanced CNC lathes add live tooling capabilities for milling, drilling and tapping without removing parts. This allows complete machining in one setup.
Advantages of CNC Turning
There are many benefits that make CNC turning popular across a broad range of industries:
- Consistent precision – CNC automation ensures every part is machined within very tight tolerances.
- Fast process – Cutting speeds are much higher than manual turning, resulting in superior productivity.
- Operator safety – The operator is removed from direct contact with cutting, improving working conditions.
- Reduced labor – One operator can supervise multiple machines, lowering labor requirements.
- Flexible production – Quick changeovers between parts are possible with stored CNC programs.
- Intricate geometries – Complex curvilinear and asymmetric shapes can be produced.
- Surface finishes – Exceptional surface finishes down to single digit Ra values are achievable.
- Automatic tool changes – The tool turret allows extended run times for high-volume production.
- Multi-axis control – Simultaneous control over multiple axes enables advanced operations.
- Easy integration – CNC turning centers can readily integrate with other processes in automated systems.
- On-machine inspection – Probing systems enable checking dimensions without removing parts.
Disadvantages of CNC Turning
Some downsides associated with CNC turning include:
- High initial costs – Both the CNC lathe and workholding equipment require major investments.
- Programming knowledge needed – While easier than manual code G-code programming, CAM software expertise is required.
- Not ideal for low volumes – The setup costs mean manual turning can be better for very low batch sizes.
- Size limitations – The maximum part swing diameter is limited by the machine bed size.
- Maintenance requirements – These machines require maintenance procedures like axis alignments to hold tighter tolerances.
- Skilled labor shortages – There is high demand for cNC machinists, programmers and service technicians.
CNC turning continues advancing with smarter software, more capable controllers and advanced features like B axis milling spindles. However, the core function of precisely spinning parts while cutting them with automatically positioned tools remains the essence of CNC turning. Understanding the fundamentals allows manufacturers to evaluate whether adding CNC turning is suitable for their part production needs. CNC Milling CNC Machining