Introduction to CNC Turning(sheet metal bending Gustave)
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- source:WEINBERG CNC Machining
How CNC Turning Works
In CNC turning, the cutting tool moves in a linear motion parallel to the axis of rotation to remove material from the surface of a cylindrical workpiece. The workpiece is held in a chuck or collet on a rotating spindle. As the part spins, the cutter machines away excess material based on programmed instructions that control its movement.
CNC turning employs Computer Numerical Control (CNC) via a machine control unit. The operator generates the machining program with CAM (Computer Aided Manufacturing) software. This program is then loaded into the CNC controller, which interprets it and controls the motion of the machine. The instructions determine the feed rate, depth of cut, spindle speed, and X-Z axis positions. This enables the automated, precision execution of the turning operations.
Key Components of a CNC Turning Machine
CNC turning centers contain several important components:
- Spindle: The spindle holds and rotates the workpiece. Higher spindle speeds allow for faster material removal rates. The spindle is powered by a motor and transmission system.
- Chuck: The chuck (usually 3 or 4 jaw) mounts onto the spindle and grips the workpiece. Collets can also hold parts for greater accuracy.
- Tool turret: An indexing tool turret holds multiple cutting tools and allows for automatic tool changes. Live tooling on the turret can perform C-axis milling operations.
- Slides: Ball screws or hydraulic systems position the tool turret and tailstock in the X and Z axes.
- Control system: The CNC controller governs the machine based on programmed instructions.
- Coolant system: Coolant is applied to the cutting area to reduce heat and flush away chips.
- Enclosure: A protective enclosure surrounds the working area to improve safety and keep out contaminants.
Benefits of CNC Turning
CNC turning offers many advantages over manual turning techniques:
- Higher precision and accuracy: CNC machines produce parts within +/- 0.005 inch tolerances. The automated process removes human errors.
- Faster production: CNC turning completes repetitive tasks faster than manual operations. Complex components can be made in minutes.
- Improved surface finishes: Precision programmed tool motion creates excellent surface finishes and maintains tight dimensional control.
- Complex geometries: CNC turning can produce complex shapes not possible by manual methods due to its multi-axis control capabilities. Eccentric turning produces complex ID and OD shapes.
- Higher repeatability: Once the CNC program is verified, the machine will repeatedly produce identical components.
- Safer operation: CNC eliminates the risks associated with manually turning dangerous or unstable parts. The enclosed work area protects the operator.
- Reduced setup time: CNC tools and cutting data are stored, slashing setup times for common jobs.
- Less skilled labor required: Extensive training is not required to operate CNC turning equipment due to its automated process. One trained programmer can oversee multiple machines.
- Unattended operation: CNC turning machines can run overnight or over weekends unmanned after initial setup.
- Improved cost efficiency: The reduction in setup times, waste, and labor costs makes CNC turning more economical for medium to high production runs.
Turning Operations Performed on a CNC Lathe
CNC turning centers can perform various cylindrical turning operations:
- Facing: Machining the end face of the part perpendicular to its axis.
- Straight turning: Reducing the diameter of a cylindrical surface. The tool feeds parallel to the part axis.
- Taper turning: Gradually reducing diameter to create a tapered shape. Uses angle offsets.
- Profiling: Cutting external contours by interpolating the X and Z-axes.
- Undercutting: Recessing an area on the inner diameter of parts.
- Grooving: Cutting narrow internal and external grooves into the part.
- Parting: Using a specially shaped tool to cut off a completed part from the raw stock.
- Threading: Single or multi-point tools cut external and internal threads.
- Drilling: Either live tools or offset boring bars drill and ream holes in parts.
- Boring: Enlarging and smoothing pre-drilled holes to tight dimensional tolerances.
More advanced CNC lathes use live tooling, Y-axis capabilities, and C/Y-axis interpolation to perform milling operations such as slotting, keyway cutting, and profiling. This allows for intricate features and reduces secondary machining requirements.
Summary
In summary, CNC turning is an automated process for precision cutting of cylindrical components. It utilizes a rotating workpiece and tool turret to machine parts based on programmed instructions. The use of CNC turning improves consistency, accuracy, surface finish, productivity, complexity, flexibility, and cost efficiency over manual turning methods. With capabilities for numerous turning, drilling, and milling operations, CNC lathes have become indispensable for modern manufacturing facilities. Continued advancements in multi-axis capabilities, spindle design, and software integration will further improve the opportunities for CNC turned parts across all industries. CNC Milling
