Introduction to Turning on a CNC Machine(how to titanium nitride coating Leona)

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Turning is one of the most common and important machining processes done on CNC (computer numerical control) machines. It involves rotating a cylindrical workpiece while cutting tools remove material to shape the piece. Turning produces rotational, axisymmetric shapes and is ideal for making parts that have cylindrical symmetry like shafts, pins, rods, and fasteners. Let's take a deeper look at how turning works on CNC machines.
Basic Principles of Turning
Turning uses a single point cutting tool to shape the external surface of cylindrical workpieces. The workpiece is held and rotated on its axis while the cutter removes unwanted material. By precisely controlling the positions and movements of the cutter, intricate shapes and features can be machined. Turning can be used to reduce the diameter of a workpiece to a desired dimension or to create contoured profiles by moving the tool at different rates as the part spins.
The key components involved in CNC turning include the turning center, cutting tool, workpiece, chuck, and tool turret. The turning center provides the rotating spindle that holds the workpiece and the motor that drives it. Cutting tools come in various shapes and materials like high speed steel, carbide, ceramic, diamond, and cubic boron nitride. The chuck securely clamps the workpiece to the spindle so it can be safely rotated at high speeds. The turret holds multiple tools and allows quick indexing between them.
There are two main types of turning operations - longitudinal turning and facing. Longitudinal turning reduces the diameter and contours the side of the workpiece. Facing cuts off material from the face of the part and creates flat surfaces. Both operations can be performed on CNC lathes during the same machining process.
Programming for CNC Turning
Creating CNC turning programs requires defining specific parameters so the machine cuts the workpiece accurately. The main program inputs include:
- Selecting cutting tools - The appropriate tool types, sizes, and materials must be chosen to perform the required operations.
- Defining feeds and speeds - The rotation rate of the spindle and traverse rate of the tools must be set based on factors like material, tooling, and desired finish.
- Specifying depths of cut - How deep each tool cuts into the workpiece is input to remove the correct amount of material.
- Setting coordinate positions - Machining locations are defined using X, Y, and Z coordinates based on the workpiece zero point.
- Programming contours - Complex shapes are created by inputting coordinated linear and arc motions.
- Adding tool compensation - Adjustments account for tool offsets from the spindle centerline.
- Choosing coolant methods - Coolant delivery helps with chip removal, cooling, and lubrication.
CNC machines allow these turning parameters to be quickly inserted and modified using conversational or G-code programming. CAD/CAM software can also be used to generate turning programs from 3D models.
Set-Up Procedure for Turning
Before machining can begin, the CNC turning center must be set up properly to run the turning operation safely and accurately:
1. Inspect Material - Check that the workpiece dimensions match the program specifications. Measure for any warpage or defects.
2. Face and Center Material - Face the workpiece to create a flat reference surface. Center drill a hole to provide a starting point.
3. Mount Workpiece - Securely clamp the workpiece in a chuck or collet attached to the spindle.
4. Install Cutting Tools - Place the required turning toolholders in the turret in the programmed sequence.
5. Verify Tool Offsets - Confirm each tool is properly set relative to the spindle centerline.
6. Set Part Zero and Work Coordinates - Touch off tools to establish the part zero position. Enter work coordinate values.
7. Check Program Code - Dry run the machine program to verify the code will run correctly.
8. Initiate Spindle and Coolant - Start the spindle rotating and turn on the coolant system.
9. Run Production - Cycle start the CNC program to begin the automated turning process.
10. Inspect Finished Parts - Verify the machined parts meet all specifications in the print.
Turning Techniques and Best Practices
Utilizing certain techniques and following best practices allows turning operations to be completed efficiently and to high quality standards:
- Select optimal feed rates and spindle speeds based on factors like tool material, depth of cut, workpiece hardness, etc. This prolongs tool life.
- Choose the tool approach that allows chips to break and evacuate easily. Conventional turning has tools cutting from the outside in while climb turning cuts from the inside out.
- Employ peck drilling cycles on deep bores to clear chips and prevent workpieces from overheating.
- Use grooving inserts to cut off finished parts and part them efficiently. ID grooving tools can bore and groove internal diameters.
- Utilize thread turning tools to cut highly precise external and internal threads, especially for odd thread forms not possible by tapping.
- Program eccentric turning operations to machine complex cam contours between centers.
- Include finishing passes with reduced depths of cut to obtain the required surface finish and dimensional accuracy.
- Apply C-axis contouring for producing intricate asymmetric contours in a single setup.
- Follow tool manufacturer's recommendations for optimal feeds, speeds, and depths of cut to maximize tool life and cutting performance.
By applying the proper techniques, programmers and machinists can fully utilize CNC turning to produce high-quality precision turned parts quickly and cost-effectively.
Turning is an essential capability of CNC machining centers that enables fabrication of critical rotational components. The basic principle involves rotating the cylindrical workpiece while cutters shape the outer contours. With CNC, turning operations can be automated for efficient precision turning. The machining parameters and sequences are defined in the CNC program. Following proper set-up procedures and turning best practices allows parts to be made within specifications. CNC turning is a metalworking process that will continue advancing manufacturing for many years to come. CNC Milling