What is CNC Turning?(how to remove chrome from motorcycle parts Lennon)
- source:MAJA CNC Machining
In CNC turning, the cutting tools move in a programmed path to remove material and shape the workpiece while it rotates at high speeds. The movements of the cutting tool are controlled by CNC machine code instructions that are programmed into the CNC machine controller. This eliminates the need for manual operation of the lathe controls.
How Does CNC Turning Work?
The basic CNC turning process involves a rotating spindle that holds the workpiece and one or more cutting tools on tool posts that move horizontally and/or vertically to remove material. Here are the steps involved:
1. The workpiece, usually cylindrical in shape, is clamped securely onto the CNC lathe chuck or between centers.
2. The operator enters the CNC program code into the machine control panel. This program contains instructions for the tools' movements and cutting parameters.
3. The chuck rotates and spins the workpiece at the desired RPM while the tool starts cutting the material.
4. As the workpiece rotates, the tool follows the programmed path and gradually chips away material from the workpiece to create the desired shape and dimensions.
5. Multiple tools can be used to perform roughing and finishing cuts. Coolants are often applied to reduce heat and improve finish.
6. Once complete, the finished part is unloaded and a new workpiece is loaded to start the cycle again.
CNC turning can produce parts with excellent dimensional accuracy and repeatability of up to 0.005mm. The process is highly suitable for producing parts in small or large batches.
CNC Turning Operations
Here are some of the common CNC turning operations:
- Facing - This involves machining the face of the workpiece to create a flat reference surface. It is performed at the start of machining.
- Turning - It is used to reduce the diameter of the workpiece and create the outside contour by moving the tool at right angles to the axis of rotation.
- Boring - The boring tool is fed into a pre-drilled hole to enlarge the hole or create specified internal dimensions.
- Threading - Thread cutting tools are used to create external or internal threads for bolts, nuts, or screws.
- Grooving/parting - A grooving tool creates grooves, slots or recesses in the part. Parting tools are used to cut off a completed part from the bar stock.
- Drilling - Performed by feeding a rotating drill into the workpiece to create holes.
- Taper turning - This involves turning a tapered contour on the workpiece by offsetting the tool.
- Knurling - It is used to create decorative knurled patterns or grooved gripping surfaces using a knurling tool.
CNC Turning Machines
CNC turning centers used for production applications typically have two axes - X and Z axis. The X axis controls the cross slide and the Z axis controls the vertical movement. Some more advanced machines have additional axes like the Y axis, C axis or B axis. Here are the main components of a horizontal CNC turning center:
- Headstock - Holds the part and rotates it under power using a spindle and chuck. Geared headstock allows low-speed high-torque turning. Belt-driven design allows faster speeds.
- Tailstock - Provides support for long workpieces using a center or steady rest. Can also hold tooling.
- Tool turret/revolver - Holds multiple cutting tools and allows automatic indexing to bring tools into use. Can be mounted on front or back of machine.
- Tool posts - Accepts single point turning or grooving tools. Quick change tool posts allow fast tool changes.
- CNC control - Computerized control receives programmed instructions and drives machine axes.
- Coolant system - Provides coolant to cutting area to cool tools, reduce friction and flush chips.
- Chip conveyor - Removes machined chips to keep the work area clear.
- Safety guards - Physical barriers protect operator from cutting hazards.
Benefits of CNC Turning
Here are some of the main advantages of CNC turning:
- Higher production rates due to fast, automated machining.
- Ability to run unattended after initial setup.
- Complex 3D shapes can be produced using interpolation.
- Excellent dimensional accuracy and repeatability. Typical tolerance of 0.005mm can be achieved.
- Multiple tools allow completing parts in a single setup. Reduces changeover time.
- Ideal for producing parts in small or large batches.
- Skilled labor not required once CNC program is developed.
- Safer to operate since operator involvement is reduced.
- Easy to modify programs for design changes or new products.
- Produces uniform output. Human errors are eliminated.
- Generates less waste and improves material utilization.
CNC Turning Applications
CNC turning is used to manufacture high precision parts across many industries including:
- Automotive - Engine valves, pistons, turbocharger wheels, axles, camshafts etc.
- Aerospace - Aircraft landing gear, engine components like impellers, nozzles.
- Medical - Joint replacement implants, surgical power tools.
- Oil and gas - Pump rotors, pipelines, valves, compressor parts.
- Construction/mining - Hydraulic cylinders, shafts, bearings, gears.
- Automation - Robotic arms, actuators, gears, shafts.
- Consumer products - Cutlery, ceramics, glass, plumbing fittings.
The ability to turn hard materials with tight tolerances makes CNC turning suitable for producing hardened steel and titanium components used in critical applications across these industries.
CNC Turning Best Practices
Follow these guidelines to get the most out of your CNC turning process:
- Select suitable material - Pick materials that are easy to machine like aluminum, brass or mild steel for first time setup.
- Apply right feeds and speeds - Optimize the cutting parameters based on material, tooling and desired finish. Start conservative initially.
- Use qualified tooling - Use brand name inserts designed specifically for turning to get best tool life and finish. HSS tooling can also work.
- Employ proper fixturing - Adequately secure the workpiece in chuck or collet to avoid vibrations. Use center support for long parts.
- Apply good chip control - Use optimum chipbreaker inserts and proper coolant direction to break and evacuate chips.
- Measure key features - In-process inspection of critical dimensions ensures early detection of any issues.
- Clean machines regularly - Keep CNC beds free of chips, dirt and grime to achieve consistent, high quality surface finishes.
- Schedule preventive maintenance - Follow the machine tool builder's maintenance schedule recommendations.
By leveraging the accuracy and automation advantages of CNC turning, manufacturers can boost productivity, quality and consistency. With the right personnel training and process planning, CNC turning can deliver precision turned parts tailored to your product requirements. CNC Milling CNC Machining