Introduction to CNC Turning(is steel an alloy Levi)

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Computer Numerical Control (CNC) turning is a machining process used to produce cylindrical parts on a CNC lathe. It is one of the most common CNC machining processes and is an efficient method for producing high precision metal parts in both small and large batch quantities.
In CNC turning, the workpiece is rotated at high speeds while a single point cutting tool removes material. The cutting tool moves in two axes (X and Z) to create the desired dimensions and features in the workpiece. By precisely controlling the movement and position of the cutting tool, complex geometric features like tapers, grooves, radii, threads, and profiles can be machined with a high level of dimensional accuracy and repeatability.
The CNC lathe follows program instructions from CAD/CAM software to position the cutting tool and coordinate its motion. This eliminates the need for manual operation of levers and handwheels as required on conventional lathes. The program contains coded instructions for the tool path, feed rate, spindle speed, depth of cut, and other parameters. Operators simply load the program into the CNC machine, install the tools, mount the workpiece, and initiate the cycle to produce the finished part.
Components of a CNC Lathe
The main components of a CNC lathe include:
- Headstock: This holds the workpiece with a chuck or collet. The spindle within the headstock rotates the workpiece at various user-defined speeds for the cutting operation.
- Tailstock: This applies pressure to the workpiece from the other end for better grip and stability. This can also hold tooling for drilling, boring and threading operations on the component.
- Tool turret: This is an indexable turret that can hold multiple cutting tools. It allows automatic and quick changes between tools during the machining process.
- Tool holder: This securely clamps the turning tool or insert into the turret. It provides precise positioning and orientation of the cutting tool.
- Bed: This is the foundation of the lathe. It consists of sturdy metal ways that guide the carriage and tailstock.
- Carriage: The carriage houses the cross slide and tool post. It moves the cutting tool longitudinally (Z-axis) into the workpiece.
- Controller: This is the computerized control system that drives the operation of the machine. It allows for programming and automation of part production.
The Advantages of CNC Turning
Some of the major advantages of CNC turning include:
- Higher precision and accuracy: CNC automation allows for machining tolerances up to 0.001 inches, significantly better than manual turning. The stored programs can be repeated for consistent quality.
- Faster process: CNC turning is much faster than manual operations. Complex parts can be produced in minutes with high efficiency.
- Reduced labor costs: One CNC operator can supervise multiple machines. The automation reduces the dependence on skilled labor.
- Flexibility: Quick changeover between components is possible by calling up different programs. Operators do not need re-position workholding fixtures.
- Intricate geometries: Complex curved, tapered and asymmetrical shapes can be produced easily on a CNC lathe.
- Safer working: The automation ensures the operator need not go near the point of operation. Risk of accidents is reduced.
- Unattended operation: Modern CNC lathes can run lights-out for hours with minimum supervision after initial setup.
- Improved quality control: In-process inspection functionality can be integrated to measure critical dimensions and statistically analyze process capability.
Common CNC Turning Operations
The basic turning processes on a CNC lathe include:
- Facing: Machining the face of the workpiece to create a flat reference surface. Done using a standard cutting tool or indexable insert.
- OD Turning: Machining the external diameter of a cylindrical or conical workpiece. Uses OD turning inserts.
- Boring: Enlarging the inside diameter of a hole. Carbide boring bars are used for holding boring inserts.
- Grooving: Cutting grooves of required dimensions on the periphery or face of the workpiece. Grooving inserts make the job easier.
- Parting: Separating a finished workpiece from the barstock by making a transverse cut. Parting blades are ideal for this operation.
- Drilling: Creating holes in the workpiece using twist drills or indexable drill inserts. Performed on the tailstock or turret.
- Tapping: Cutting internal screw threads using a tap tool. Again done on the tailstock or turret.
- Threading: Single or multi-point insert cutters can machine external threads on profiles.
Programing CNC Turning Cycles
Here are some ways CNC turning cycles are programmed:
1. Manual programming: The G-codes and M-codes are written manually based on the drawing dimensions and required tool motions. Close knowledge of CNC codes is essential.
2. CAD/CAM software: The model geometry is created on CAD. The CAM module then automatically generates the toolpaths and CNC code through post-processors.
3. Conversational programming:Simply involves answering a series of software prompts to describe the component profile. The code is generated automatically.
4. Teach mode: Here the programmer jogs the machine in real time to input the tool positions and feeds. The control system records the motions to create the program.
5. Editing existing programs: Prior similar programs can be edited and modified to suit the new workpiece requirements. This saves programming time.
A typical CNC turning program specifies important parameters like feed rate, spindle speed, depth of cut, tool selection, coolant use, coordinate positions and much more. The program is simulated initially for error checking before running on the machine.
Setup Procedure for CNC Turning
The general steps to set up a CNC lathe operation are:
1. Study the engineering drawing to understand all component features and specifications that need to be achieved.
2. Select workholding method (3/4 jaw chuck, collets, faceplates, etc.) based on the workpiece geometry and operations needed.
3. Choose the insert cutting tools, drills, taps, boring bars required as per the sequence of operations.
4. Load the cutting tools in their designated positions on the turret/tool post. Set the tool offsets.
5. Mount the workpiece on the chuck and dial in the part to indicate its true position. Set work coordinate system.
6. Specify machining parameters like speeds, feeds, depth of cut, and coolant settings in the program.
7. Perform a trial run to check for any interferences or collisions between tool and workpiece.
8. Initiate the machining cycle after everything checks out fine. Monitor the process and measure samples.
9. Inspect finished components for conformance to specifications and accuracy achieved.
CNC turning is a versatile and essential machining process used extensively across manufacturing industries. With programming and setup facilitated by CAD/CAM software, CNC lathes provide a highly efficient method of automated precision turning. CNC Milling CNC Machining