Overview of CNC machining: CNC machining process, common processes and advantages

CNC machining (Computer Numerical Control Machining) is a precision manufacturing process based on computer program control. It utilizes a computer numerical control (CNC) system connected to the machine tool to control the machine's cutting tools. G-codes and M-codes containing machining parameter instructions, derived from the CAD model, are forwarded to the machine tool. The machine then follows a pre-set path through turning, drilling, milling, and other machining operations, removing material from the workpiece. This allows for precise machining of materials such as metal, plastic, and wood, resulting in parts or products that meet design requirements.

CNC machining typically involves four basic steps, and regardless of the machining process used, the following process must be followed:

• Step 1: Designing the CAD Model

  The first step in CNC machining is to create a 2D or 3D model of the product. Designers typically use AutoCAD, SolidWorks, or other CAD (computer-aided design) software to build an accurate model of the product. For more complex parts, 3D modeling can more clearly demonstrate product features such as tolerances, structural lines, threads, and assembly interfaces.

• Step 2: Converting to a CNC-Compatible Format

  CNC machines cannot directly read CAD files. Therefore, CAM (computer-aided manufacturing) software, such as Fusion 360 and Mastercam, is required to convert the CAD model into CNC-compatible numerical control code (such as G-code). This code instructs the machine tool to execute precise cutting paths, feed rates, tool motion paths, and other parameters to ensure machining accuracy.

• Step 3: Select the Appropriate Machine Tool and Set Machining Parameters

  Based on the part's material, shape, and machining requirements, select an appropriate CNC machine (such as a CNC milling machine, lathe, or grinder). The operator then performs the following preparatory tasks:

  • Install and calibrate the tool
  • Set parameters such as machining speed, feed rate, and depth of cut
  • Ensure the workpiece is securely fixed to prevent movement during machining
• Step 4: Perform CNC Machining

  Once all preparatory steps are complete, the CNC machine tool can execute the machining task according to the pre-set CNC program. The machining process is fully automated, with the tool cutting along the defined path until the part is formed.

• Step 5: Quality Inspection and Post-Processing

  After machining, the part undergoes quality inspection to ensure that its dimensional accuracy and surface finish meet the design requirements. Inspection methods include:

  • Dimensional measurement: Dimensional inspection using calipers, micrometers, or a coordinate measuring machine (CMM)
  • Surface finish inspection: Checking the surface roughness of the part to determine if additional polishing or painting is necessary
  • Assembly testing: If the part will be assembled with other components, assembly testing is performed to ensure compatibility

  If necessary, post-processing such as deburring, heat treatment, or surface coating may be performed to enhance part performance and durability.

Although the CNC machining process is automated, CNC technicians still play a vital role in addressing both expected and unexpected failures and ensuring smooth machining. The following are the main responsibilities of a CNC technician:

• Confirming Product Specifications: Accurately understanding product dimensions, tolerances, and material requirements based on order requirements and technical documentation.

• Interpreting Engineering Drawings: Reading blueprints, hand sketches, and CAD/CAM files to understand product design details.

• Creating CAE Models: Utilizing Computer-Aided Engineering (CAE) software to optimize machining plans and improve machining accuracy and efficiency.

• Aligning and Adjusting Tools and Workpieces: Ensures that cutting tools, fixtures, and workpieces are properly installed and adjusted for optimal machining conditions.

• Installing, Operating, and Disassembling CNC Machines: Properly installing and disassembling CNC machines and their accessories, and proficiently operating various CNC equipment.

• Monitoring Machine Operation: Observing machine speed, tool wear, and machining stability to ensure proper operation.

• Inspection and Quality Control of Finished Products: Inspect finished parts to identify defects and ensure they meet quality standards.

• Confirm Part Conformity with CAD Model: Compare the actual part to the CAD design to confirm that the product's dimensions, geometry, and tolerances accurately meet design requirements.

The CNC technician's professional skills and meticulous approach are crucial to ensuring machining quality, improving production efficiency, and reducing scrap, and are an integral part of the CNC machining system.

CNC (Computer Numerical Control) machining technology is widely used in the manufacturing industry for precision machining of various metal and non-metal materials. Different CNC machining processes are required depending on the machining requirements. The following are some common CNC machining processes:

• 1. CNC Milling

  CNC milling is a machining method that uses a rotating tool to cut workpieces. It is suitable for machining flat surfaces, curved surfaces, grooves, holes, and complex geometric structures. Its main features are as follows:

  • It is suitable for machining a variety of materials, such as aluminum, steel, stainless steel, and plastics.
  • It is capable of high-precision and high-efficiency multi-axis machining (such as 3-axis, 4-axis, and 5-axis milling).
  • It is suitable for mass production of precision parts, such as housings, brackets, and molds.
• 2. CNC Lathe Machining

  CNC lathes use a rotating workpiece and a fixed tool for cutting. They are primarily used for machining cylindrical parts, such as shafts, rings, and disks. Their main features are as follows:

  • It is suitable for efficient machining of symmetrical rotating parts.
  • It can process internal and external circles, tapered surfaces, threads, grooves, and other structures. Suitable for mass production, it is commonly used in the manufacturing of automotive parts, aviation bearings, electronic connectors, and more.
• 3. CNC Drilling

  CNC drilling is the process of machining through or blind holes in a workpiece. It is typically used for screw holes, pin holes, and other components used in part assembly. Its main features are as follows:

  • Suitable for machining holes of various depths and diameters.
  • Can be combined with tapping to create threads within the hole.
  • Applicable to a variety of materials, including metals, plastics, and composites.
• 4. CNC Boring

  CNC boring is used to enlarge or fine-tune existing holes to improve dimensional accuracy and surface finish. Its main features are as follows:

  • Suitable for machining high-precision, large-sized holes.
  • Commonly used for parts requiring tight tolerance control, such as engine blocks and hydraulic cylinders.
  • Can be combined with other processes, such as milling and turning, to achieve more complex machining needs.
• 5. CNC Electric Discharge Machining (EDM)

  Electrodischarge machining (EDM) uses pulsed electrical discharges between an electrode and a workpiece to remove material. It is suitable for machining high-hardness materials and complex parts.

  • It is suitable for materials difficult to machine with traditional cutting methods, such as carbide and titanium alloys.
  • It can process fine details and high-precision molds, such as injection molds and precision electronic components.
  • It is suitable for stress-free machining without mechanical damage to the workpiece surface.

CNC machining processes are diverse, each with its own unique characteristics, suited to different machining needs. Milling, turning, and drilling are the most common basic processes, while EDM, laser cutting, and water jet cutting are suitable for machining specialized materials and complex structures. Choosing the right CNC machining process not only improves production efficiency but also ensures part precision and quality, meeting the high standards of modern manufacturing.

CNC (Computer Numerical Control) machining has become a core technology in modern manufacturing. Compared to traditional manual or semi-automatic machining methods, CNC machining offers higher precision, efficiency, and consistency. The following are the main advantages of choosing CNC machining:

• High Precision and Consistency

  CNC machining uses computer programs to control tool movement, ensuring precise dimensions and shape for every workpiece. Compared to traditional machining methods, CNC machining can achieve micron-level accuracy and ensure consistency across mass production, eliminating product deviations caused by human error. It is suitable for machining parts with high tolerance requirements, such as in industries such as aerospace, medical devices, and electronics. Multi-axis machining (such as 5-axis CNC) can also be used to achieve complex geometries, reducing setup times and improving precision.

• Improved Production Efficiency

  CNC machine tools can operate continuously, reducing manual intervention and improving production efficiency. Furthermore, through automatic tool changing (ATC) and multi-axis machining technology, CNC machines can complete multiple machining steps in a single setup, significantly shortening production cycles and making them suitable for large-scale production. This reduces tool change and machine setup time, thereby increasing output per unit time. Compared to traditional manual machining, CNC machines can operate 24/7, reducing production costs.

• Strong Capability for Complex Part Processing

  CNC machining can easily handle parts with complex geometries and high precision requirements. Multi-axis CNC machines, in particular, can complete multi-surface machining in a single operation, avoiding the accumulation of errors caused by repeated clamping. This makes them suitable for industries with high part complexity requirements, such as aerospace, medical devices, and automotive manufacturing. They can also process spiral shapes, complex internal structures, and curved surfaces, which are difficult to achieve using traditional processes.

• Compatibility with Various Materials

  CNC machining is suitable for a wide range of materials, including metals (aluminum alloys, stainless steel, titanium alloys, copper, etc.), plastics (POM, ABS, nylon, etc.), composite materials, and ceramics. This allows CNC machining to meet the needs of diverse application scenarios. Furthermore, CNC machining can also process high-strength and high-hardness materials, such as aircraft-grade titanium alloys and high-strength stainless steel, making it suitable for precision component manufacturing in various industries, including electronics, medical, and automotive.

• Reduced Production Costs

  Although CNC machining requires a significant initial investment in equipment, it can significantly reduce unit costs in the long term. Its high machining capacity, low scrap rates, and labor-saving features make CNC machining more economical for large-scale production.