In computer numerical control processing, the machine is programmed to handle a wide range of operations. For a successful CNC machining operation, you will start by designing the part, programming the machine, and allowing it to execute different functions.
Today, we shall explore every aspect of CNC machining.
What is CNC Machining?
CNC machining is a modern and widely practiced manufacturing process that involves material removal under the direction of digitally controlled turning tools. This way, you can efficiently carry out automated production with high accuracy levels.
Key Steps in CNC Processing Parts
Step 1: Design Stage
· Conceptual Design
The conceptual design allows you to contemplate and visualize how the part you intend to produce will look. Having a conceptual design is necessary to avoid machining issues later on, when it is too late and too costly. Key elements you consider at this stage are the material to use, part parameters and allowed tolerances.
· CAD Modeling
You are able to develop a digital presentation of your part through CAD modeling. This digital form is interpretable by your CNC machine and can be in either two-dimension or even three-dimensions.
· Design for Manufacturability (DFM)
With this step, you ensure your part design can be executed by the CNC machine easily without posing challenges. Core aspects of DFM are maintaining functionality while being practical. In designing for manufacturability, remember to evaluate the machine capability. This way, your machining process is not hindered by complex set ups and extended machining time.
Here are some guidelines when designing for manufacturability:
- Avoid parts requiring custom workholding and fixtures
- Ensure the machining tools are free moving with easy access
- Make your geometries simple, minimizing complexities
- Relegate tight tolerances only for critical part features
- Sparingly apply surface finishes
- Use easily available and machineable materials
Step 2: CAM Programming
· Importing CAD into CAM Software
Your CAD design has to be converted into a language the CNC machine can interpret. Importation of CAD into CAM allows the machine to come up with toolpaths with minimal errors, hindering the transition.
· Toolpath Generation
What guides the movement of the CNC machine turning tools is determined by the toolpath. The CNC machine determines toolpaths by interpreting the desired part dimensions and evaluating its reach in axis movement.
· Turning Strategies
Constitutes the approach to how the CNC machine carries out its operations. Turning strategy is influenced by factors like the feed speed, which influences surface quality and rate of tool wear.
· Simulation and Verification
This step allows you to put the program to the test and confirm its status in terms of execution. This way, you don’t have to feed an erroneous programme to the CNC machine. Simulation and verification prevent losses associated with programming errors.
Step 3: CNC Programming
· Structure of a CNC program
When you break down a CNC program, it is down to lines of code, with each line carrying a command function. Some information contained in a CNC program includes the part identity and machining instructions.
· G and M-codes
G-codes are preparatory codes allowing you to describe the mode of the turning machine and the desired movement. M-Codes make for miscellaneous codes with control of secondary functions, like starting the spindle.
· Parameterization
Parametric programming streamlines CNC programs, enhancing their efficiency when undertaking repetitive operations. Rather than hard-coding programmes every time, you can implement parameterization, harnessing its logic storage capacity.
· Dry Runs
A dry run is how you determine your program runs as intended without actually performing the intended operation. Dry runs are a pre-operation litmus test that confirms the machine will respond as dictated.
Step 4: Setup Process
· Machine Preparation
It is important that you check the machine before engaging it in CNC operations. Your machine should have auxiliary functionality and be capable of powering up safely. When preparing the machine, ensure it can move in the program’s defined axes. Also, ensure the tool magazine is correctly tooled and the coolant system is filled up.
· Workholding
In workholding, you provide a way to secure your workpiece during machining. This ensures it does not move during operations, causing defects such as deflection and misalignment. Some examples of workholding devices are clamps, fixtures and jigs.
· Tool Setup
Having the right tool in the right position is critical for successful CNC processing. Your tool setup should be such that the tool is easily accessible and within reach of the workpiece. Where you’re using multiple tools, it should allow for quick changeovers.
Step 5: Machining with CNC
· Loading Program
In order to initiate CNC processing, you first have to load the program into the machine. The machine stores the program in a quickly accessible location from whence it can be retrieved when needed.
· Test Run
You determine whether the loaded program functions as expected by conducting a test run. This test checks whether the machine tool responds as programmed and thus executes the designated operation faithfully.
· Automated Execution
The CNC process is an automated function relying on preinstalled instructions to direct its operations. Once you load a program, run it and confirm its efficiency, you can roll out the CNC processing. Some of the operations you can automatically execute in CNC processing include:
o Hole-Making: Drilling, reaming, boring, counterboring, tapping, and countersinking.
o Milling: Face and slab milling, slitting, profiling, spiral and thread milling, pocket milling and gear turning.
o Turning: Operations such as straight turning, grooving and taper turning.
o Advanced Machining: Includes multi-axis machining, micro-machining and thread whirling.
o Finishing: Actions like lapping, honing, grinding and burnishing.
· Real-time Monitoring
You don’t just let the CNC machine operate without supervision. The machine can malfunction and require immediate attention. An elaborate sensor system can help you identify inherent system issues. You can also point out malfunctions by listening for unusual noises.
· Cycle Time Management
How long a CNC process lasts from start to finish describes its cycle time. Proper management of cycle time ensures you can meet production goals on time. It also enhances machine utilization.
Step 6: CNC Process Quality Control
· Probing
Probing allows you to determine a part’s dimensions by using adaptive control features. Common equipment you find useful in probing includes touch probes, which physically perform probing, and laser probes that use laser radiation.
· Tool Wear and Breakage
Sometimes during operation, either or both the tool and workpiece can break for one reason or another. You can determine breakage or wear by visual inspection or by capturing unusual noises like vibrations or clanging on metal. Some CNC machines are equipped with cameras that enhance the scope of observation.
· Process Adjustments
As operations continue on a CNC machine, it is possible for you to make adjustments based on your own evaluation. For instance, you can observe the spindle speed as being too high and adjust it accordingly. This allows you to ensure the resulting work is of an acceptable quality.
Step 7: Post CNC Processing Operations
· Surface Finishing
You perform surface finish on workpieces whose surface quality is compromised or for aesthetic reasons. The machining process can cause imperfections like dents, which you can clear using finishing methods.
· Dimensional Inspection
At the beginning of the machining process, you have the desired part dimensions and geometries. Consequently, upon completion of the process, you need to confirm that these dimensions and geometries have been met as initially desired. Different tools and equipment, like vernier calipers and micrometer screw gauges, aid you in determining the dimensional accuracy of parts.
· Functional Testing
You determine the success or failure of your machined part in performing as expected by testing it out in its area of application. Your part has to fit well during assembly and operate without any anomaly to pass the test of functionality.
Feedback and Optimization
In CNC processing, you can evaluate the machine function and performance and make relevant improvements to improve its function. As a result, succeeding operations are more optimized and efficient. The feedback process is an essential tool for improving performance and process quality.
How to Reduce the Cost of CNC Machining
Design for manufacturability using simple geometries, standardized tolerances, minimal thin walls and deep cavities as well as using consolidate features.
- Select machinable and easily available materials such as aluminum and its alloys.
- Use standard tooling with effective setup emphasizing, aspects like tool life management and modular fixturing.
- Optimize processes by reducing cycle time, producing in batches, implementing adaptive machining and automation.
- Minimize secondary operations and utilize combined finishing steps.
Examples of CNC Machined Parts
- Aerospace Industry: Turbine blades, brackets, compressor discs, landing gear components, housings.
- Automotive Industry: Engine blocks, transmission components, cylinder heads, brake parts, suspension arms.
- Medical Industry: Implants, prosthetics, surgical instruments.
- Electronics Industry: Connector housings, heat sinks, and cooling plates.
- Military Applications: Vehicle parts, weapon components, device housings.
- Energy Industry: Drill bits, valve bodies, turbine components, housings.
Conclusion
Embracing CNC processing for your part production ensures you benefit from the high repeatability and accuracy of especially complex parts. Furthermore, CNC processing is highly flexible, allowing use in a diverse range of industries.
OTURN provides advanced, high-performance CNC lathes and other CNC equipment to meet diverse process requirements. Our equipment not only improves machining efficiency and quality but also offers stable and reliable performance, enabling customers to achieve intelligent and automated production. Selecting high-quality machine tools is key to ensuring machining accuracy, increasing production capacity, and reducing production costs.
