What is CNC Machine? Structure and Operating Principles of CNC Machines

In the field of mechanical processing, CNC machines have emerged to meet high demands for precision and product finishing. Let’s explore in detail with RX Tradex what CNC machines are, their structure, and operating principles in the modern manufacturing industry, to gain a clearer understanding of their applications and benefits in production processing.

1. What is a CNC Machine?

CNC (Computer Numerical Control) is a widely used type of machine in mechanical processing industries, automated and controlled with computer assistance. Its components operate based on a pre-programmed sequence of events to produce products with standardized shapes and dimensions as required. Every machining operation performed by a CNC machine relies on the control of a computer system. CNC machines are also known as CNC machining centers, CNC machining centers, or CNC processing machines.

2. Structure and Operating Principles of CNC Machines

Structure of CNC Machine:

• Machine Frame: typically made of cast iron or steel, this component provides rigidity and maintains the stability of other machine parts during machining.
• Machine Table: a flat surface where the workpiece (raw material) is placed and secured for machining.
• Spindle: the rotating component of the CNC machine that holds and spins the cutting tool at high speeds, enabling precise and efficient machining operations.
• Motors and Drive System: the drive system can be ball screws, lead screws, or linear guideways, playing a crucial role in accurately controlling the position and speed of the machine table and spindle.
• Automatic Tool Changer (ATC) System: includes a magazine or tool storage and an automatic tool-changing mechanism. Its function is to automatically change cutting tools during machining, enhancing productivity and reducing machine downtime.
• Control System: comprises the CNC computer and software, keyboard, display screen, and other control units. The control system inputs data, programs machining commands, and operates the machine according to the programmed instructions.
• Cooling and Lubrication System: consists of coolant pumps, pipes, and oil or coolant spraying devices. These systems lubricate cutting tools and workpieces during machining, reducing friction and temperature, extending tool life, and ensuring machining surface quality.
• Safety System: includes sensors, safety switches, and other protective devices. They are designed to ensure operator safety and protect the CNC machine from damage due to accidents.

Operating Principles:

A CNC machine operates based on a machining program prepared using CAM software. This program controls the motion of the workpiece and cutting tool with high precision. The specific steps are as follows:

• Step 1: CAD 2D/3D design files are exported, then programmed using CAM software to generate toolpath programs.
• Step 2: The program is processed to convert CAM instructions into a machine-readable code, typically G-Code.
• Step 3: The G-Code program is loaded into the CNC machine along with all necessary cutting tools such as end mills, thread mills, drills, etc.
• Step 4: Subsequently, the machine is set to automatic mode to start, controlling all machine functions including movement, feed rates, spindle speed, tool changes, etc., for machining the part.
• Step 5: The machine operator monitors the machining process and makes adjustments as necessary to ensure stable operation and handle any issues that may arise.

3. Advantages and Disadvantages of CNC Machines

Advantages:

• High Accuracy: CNC machines are controlled by computer programs, ensuring precision and consistency of products, meeting strict requirements across various industries.
• Superior Work Efficiency: CNC machines can operate 24/7 for extended periods at high speeds, increasing production output and work efficiency significantly compared to manual operations, suitable for mass production.
• High Flexibility: CNC machines can process various types of materials with different shapes, from simple to complex 3D parts, and can easily adjust parameters with computer assistance.
• Cost Saving in Production: CNC machines optimize material usage, minimizing waste during machining. Additionally, they reduce labor costs, shorten production times, and contribute to increased profitability for businesses.
• Ensures Occupational Safety: CNC machines automate the machining process, minimizing the risk of accidents for operators.
• Facilitates Automation in Production Processes
• High productivity can reduce product costs to increase competitiveness.

Disadvantages:

• High Initial Investment: Due to the use of advanced technology, CNC machines require significant initial capital investment.
• Requires Skilled Operators: Operating CNC machines requires experienced personnel with specialized knowledge of computers and machining.

4. Classification of CNC Machines

4.1. Based on Machine Tool Type

According to the type of machine tool, some common types include:

CNC Lathe Machine: Used to shape rotating parts, such as shafts, rings, gears, and threads. Besides standard turning operations, CNC lathes can also perform drilling, grooving, chamfering, and polishing.

CNC Milling Machine: Operates by fixing a material on the machine table and using milling cutters to remove excess material. With 3 axes X, Y, Z controlled by motors and gear systems, CNC milling machines can move in various directions to create parts as required. The main function of CNC milling machines is milling, threading, and drilling with high precision.

CNC Grinding Machine: Uses grinding wheels or grinding discs to remove excess material and grind flat surfaces and polish surfaces. Compared to manual grinding machines, CNC grinding machines can process materials with high hardness, such as steel and alloys.

CNC Drilling Machine: CNC drilling machines can drill holes with uniform accuracy and depth or create holes in various shapes such as twist holes, round holes, rectangular holes… The parameters of the drilling process such as hole diameter, drilling depth and speed are controlled via computer, ensuring the accuracy of the output.

4.2. Based on Cutting Methods

CNC Router: CNC routers perform cutting operations on materials with any curve, zigzag line in 2D, 3D space that metal cutting machine can not be done, apply to cut wood, plastic, synthetic materials or cut aluminum and other soft metals with high accuracy of complicated details.

CNC Plasma Cutting Machine: The machine uses plasma spindle heads with high temperature to cut the surface of objects made from metal with high hardness such as iron, steel. This line is being widely used in almost every mechanical manufacturing industry with the diversity of the types of products such as hand-held cutting machine, small cutting machines.

CNC Laser Cutting Machine: The machine uses laser beam generating high-energy laser radiation, through a focusing optical system focused beam, output laser beam to cut materials, metals or non-metals. The CNC laser cutting process is completely automated, ensuring high accuracy products, meeting the strict requirements of processing standards.

4.3. Based on the number of axes

CNC 3-axis machine: Allows the cutter to move in 3 directions X, Y, Z with high accuracy, while the blanks remain in the same position while the cutting tool is working vertically to the XYZ plane. This is consistent with the parts that do not require a lot of depth and smaller details inside.

4-axis CNC machine: Machining 4 axis implies that the blanks are processed in the same way with a 3-axis machine, but a supplementary rotary motion around axis X is called axis A. The rotation allows the blanks to be cut around axis B. This method is beneficial when holes or cuts need to be made on the surface of the blanks. Supplementing the fourth axis (axis A) allows the blanks to be automatically flipped, so the machine can remove materials from both sides.

5-axis CNC Machine: is a machining method where the raw material blank is machined from multiple sides simultaneously. This machining center has basic movements along the X, Y, Z axes and utilizes 2 out of the 3 rotary axes A, B, C to perform machining. The rotary axes A, B, C execute rotational movements around the corresponding X, Y, and Z axes. Each axis performs a distinct task and serves different functions.

5. Applications of CNC Machines in Daily Life

CNC technology has been developed and applied in daily life, bringing numerous benefits to humanity. Currently, various types of CNC machines are widely used in industrial manufacturing sectors, particularly in relation to metal materials such as machining, machinery manufacturing, and equipment installation. Some fields where CNC technology is applied include:

Automobile manufacturing: Used to enhance efficiency and quality control in assembly lines. Also utilized in fabricating components and parts to refine automotive components.

Manufacturing of locomotive and subway heads: enables precise machining of locomotive and subway heads. Fabrication of machine components and parts within the mechanical engineering industry.

Maritime industry: Applied in machining spare parts for ships and oil tankers.

Aerospace industry: Used for machining satellite equipment, aircraft components, and spacecraft.

Medical industry: Enables precise machining of medical device components, supports biological implants, surgical instruments, orthopedics, and dentistry.

6. Some Famous CNC Machine Brands

CNC machines are modern technologies that offer optimal solutions for the mechanical processing industry, hence they involve high investment costs. Understanding and selecting suitable CNC machine models is crucial. Below, we introduce some quality CNC machine brands from reputable labels that are widely trusted by businesses today:

6.1. Okuma CNC Milling/Turning Machines

Okuma is a leading manufacturer from Japan in the global CNC machine industry. Okuma consistently equips its machines with advanced features and develops cutting-edge technologies such as the Okuma OSP electronic control system, cooling systems, and many other functions to serve mechanical machining operations.

6.2. Citizen CNC Turning Machines

Citizen is another prestigious brand from Japan specializing in CNC machine tools. This brand is renowned for modern CNC turning machines, especially Swiss-type CNC lathes popular in industries such as automotive, electronics, medical, and watchmaking. Additionally, the brand is known for other types of CNC machines including multi-axis lathes, milling machines, and grinders. These machines are applied in machining shaft components with unlimited length and large quantities.

6.3. Brother CNC Milling Machines

With powerful engines, advanced technology, and user-friendly interfaces, Brother has become one of the most popular brands today. Brother CNC milling machines feature durable main spindle motors, robust machine structures, and efficient chip management systems to ensure optimal performance and productivity. Brother CNC machining centers are suitable for manufacturing electric vehicles, motorcycles, smartphones, and computers.

7. CNC Machine Pricing

The price of CNC machines can range from several hundred million to one billion VND for small (basic) machines, and several billion VND or more for larger capacity CNC machines.

The price of CNC machines depends on factors such as:

• Size and machining capabilities: Each type of CNC machine will have different sizes and machining capabilities. Larger machines capable of machining more complex details will have higher prices.
• Brand and quality: CNC machines from reputable manufacturers are always considered to have good quality and durability. Therefore, their prices will be higher compared to machines from other manufacturers.
• Features and technology: CNC machines that incorporate superior new technologies and features will have higher prices than those using older technologies and features.

Conclusion:

Understanding the construction, operational principles, and features of CNC machines helps businesses find optimal solutions for their manufacturing operations, ensuring high productivity and quality. This contributes to bringing businesses closer to automation in production. Join the Vietnam Manufacturing Expo 2024 organized by RX Tradex to learn more about the most advanced manufacturing technologies today, helping optimize the manufacturing operations of your business.