What is a CNC (Computer Numerical Control) machine tool? Do you know its definition?

CNC Machine Tools: The Core Force in Modern Machining

I. Introduction
In the field of mechanical manufacturing today, CNC machine tools undoubtedly occupy an extremely important position. Their emergence has completely changed the traditional mode of mechanical machining, bringing unprecedented high precision, high efficiency, and high flexibility to the manufacturing industry. With the continuous progress of science and technology, CNC machine tools have been continuously developing and evolving, becoming indispensable key equipment in modern industrial production, profoundly influencing the development patterns of numerous industries such as aerospace, automobile manufacturing, shipbuilding industry, and mold processing.

 

II. Definition and Components of CNC Machine Tools
CNC machine tools are machine tools that achieve automated machining through digital control technology. They mainly consist of the following parts:
Machine Tool Body: It includes mechanical components such as the bed, column, spindle, and worktable. It is the basic structure of the machine tool, providing a stable mechanical platform for machining. The structural design and manufacturing precision directly affect the overall performance of the machine tool. For example, a high-precision spindle can ensure the stability of the cutting tool during high-speed rotation, reducing machining errors.
CNC System: This is the core control part of CNC machine tools, equivalent to the “brain” of the machine tool. It can receive and process program instructions, precisely controlling the motion trajectory, speed, feed rate, etc. of the machine tool. Advanced CNC systems possess powerful computing capabilities and rich functions, such as multi-axis simultaneous control, tool radius compensation, and automatic tool change control. For example, in a five-axis simultaneous machining center, the CNC system can precisely control the motion of five coordinate axes simultaneously to achieve the machining of complex curved surfaces.
Drive System: It includes motors and drivers, responsible for converting the instructions of the CNC system into the actual motion of each coordinate axis of the machine tool. Common drive motors include stepping motors and servo motors. Servo motors have higher precision and response speed, capable of meeting the requirements of high-precision machining. For example, during high-speed machining, servo motors can quickly and accurately adjust the position and speed of the worktable.
Detection Devices: They are used to detect parameters such as the motion position and speed of the machine tool, and feed back the detection results to the CNC system to achieve closed-loop control and improve machining precision. For example, a grating scale can accurately measure the displacement of the worktable, and an encoder can detect the rotational speed and position of the spindle.
Auxiliary Devices: Such as cooling systems, lubrication systems, chip removal systems, automatic tool change devices, etc. The cooling system can effectively reduce the temperature during the machining process, extending the service life of the cutting tool; the lubrication system ensures good lubrication of each moving part of the machine tool, reducing wear; the chip removal system promptly cleans the chips generated during machining, ensuring a clean machining environment and the normal operation of the machine tool; the automatic tool change device improves machining efficiency, meeting the requirements of multi-process machining of complex parts.

 

III. Working Principle of CNC Machine Tools
The working principle of CNC machine tools is based on digital control technology. First, according to the machining requirements of the part, use professional programming software or manually write CNC programs. The program contains information such as the technological parameters, tool path, and motion instructions of the part machining, represented in the form of codes. Then, input the written CNC program into the CNC device through an information carrier (such as a USB disk, network connection, etc.). The CNC device decodes and performs arithmetic processing on the program, converting the code instructions in the program into motion control signals for each coordinate axis of the machine tool and other auxiliary control signals. The drive system drives the motors to operate according to these control signals, driving the coordinate axes of the machine tool to move along the predetermined trajectory and speed, while controlling the rotational speed of the spindle, the feed of the cutting tool, and other actions. During the machining process, the detection devices monitor the motion state and machining parameters of the machine tool in real time and transmit the feedback information to the CNC device. The CNC device makes real-time adjustments and corrections according to the feedback information to ensure machining precision and quality. Finally, the machine tool automatically completes the machining of the part according to the requirements of the program, obtaining the finished part that meets the requirements of the design drawing.

 

IV. Characteristics and Advantages of CNC Machine Tools
High Precision: CNC machine tools can achieve machining precision at the micron or even nanometer level through the precise control of the CNC system and high-precision detection and feedback devices. For example, in the machining of aero-engine blades, CNC machine tools can precisely machine the complex curved surfaces of the blades, ensuring the shape precision and surface quality of the blades, thereby improving the performance and reliability of the engine.
High Efficiency: CNC machine tools have a relatively high degree of automation and rapid response capabilities, enabling operations such as high-speed cutting, rapid feed, and automatic tool change, significantly shortening the machining time of parts. Compared with traditional machine tools, the machining efficiency can be increased several times or even dozens of times. For example, in the mass production of automobile parts, CNC machine tools can quickly complete the machining of various complex parts, improving production efficiency and meeting the requirements of large-scale production in the automobile industry.
High Flexibility: CNC machine tools can easily adapt to the machining requirements of different parts by modifying the CNC program, without the need for complex adjustments of tooling fixtures and modifications of the mechanical structure of the machine tool. This enables enterprises to quickly respond to market changes and realize multi-variety, small-batch production. For example, in mold manufacturing enterprises, CNC machine tools can quickly adjust the machining parameters and tool paths according to the design requirements of different molds, machining various shapes and sizes of mold parts.
Good Machining Consistency: Since CNC machine tools machine according to the preset program, and the various parameters in the machining process remain stable, they can ensure that the machining quality of the same batch of parts is highly consistent. This is of great significance for improving the assembly precision and overall performance of the product. For example, in the machining of precision parts of electronic products, CNC machine tools can ensure that the dimensional precision and surface quality of each part are the same, improving the pass rate and reliability of the product.
Reduction of Labor Intensity: The automated machining process of CNC machine tools reduces human intervention. Operators only need to input programs, monitor, and perform simple loading and unloading operations, significantly reducing labor intensity. At the same time, it also reduces machining errors and quality problems caused by human factors.

 

V. Classification of CNC Machine Tools
Classification by Process Application:
Metal Cutting CNC Machine Tools: Such as CNC lathes, CNC milling machines, CNC drill presses, CNC boring machines, CNC grinding machines, CNC gear machining machines, etc. They are mainly used for the cutting machining of various metal parts and can machine different shape features such as planes, curved surfaces, threads, holes, and gears. For example, CNC lathes are mainly used for the turning machining of shaft and disc parts; CNC milling machines are suitable for the machining of complex-shaped planes and curved surfaces.
Metal Forming CNC Machine Tools: Including CNC bending machines, CNC presses, CNC tube bending machines, etc. They are mainly used for the forming machining of metal sheets and tubes, such as bending, stamping, and bending processes. For example, in the sheet metal processing industry, a CNC bending machine can accurately bend metal sheets according to the set angle and size, producing various shapes of sheet metal parts.
Special Machining CNC Machine Tools: Such as CNC electric discharge machining machines, CNC wire cutting machines, CNC laser machining machines, etc. They are used to machine some parts with special material or shape requirements, achieving material removal or machining through special machining methods such as electric discharge and laser beam irradiation. For example, a CNC electric discharge machining machine can machine high-hardness, high-toughness mold parts, having an important application in mold manufacturing.
Other Types of CNC Machine Tools: Such as CNC measuring machines, CNC drawing machines, etc. They are used for auxiliary work such as part measurement, detection, and drawing.

 

Classification by Controlled Motion Trajectory:
Point-to-Point Control CNC Machine Tools: They only control the accurate position of the cutting tool from one point to another, without considering the trajectory of the cutting tool during the movement, such as CNC drill presses, CNC boring machines, CNC punching machines, etc. In the machining of a CNC drill press, only the position coordinates of the hole need to be determined, and the cutting tool quickly moves to the specified position and then performs the drilling operation, with no strict requirements on the shape of the moving path.
Linear Control CNC Machine Tools: They can not only control the starting and ending positions of the cutting tool or worktable but also control the speed and trajectory of their linear motion, capable of machining stepped shafts, plane contours, etc. For example, when a CNC lathe is turning a cylindrical or conical surface, it needs to control the cutting tool to move along a straight line while ensuring the accuracy of the motion speed and trajectory.
Contour Control CNC Machine Tools: They can simultaneously control two or more coordinate axes continuously, making the relative motion between the cutting tool and the workpiece meet the curve requirements of the part contour, capable of machining various complex curves and curved surfaces. For example, CNC milling machines, machining centers, and other multi-axis simultaneous machining CNC machine tools can machine the complex free-form surfaces in aerospace parts, the cavities of automobile molds, etc.

 

Classification by Characteristics of Drive Devices:
Open-Loop Control CNC Machine Tools: There is no position detection feedback device. The instruction signals issued by the CNC system are unidirectionally transmitted to the drive device to control the motion of the machine tool. Its machining precision mainly depends on the mechanical precision of the machine tool itself and the precision of the drive motor. This type of machine tool has a simple structure, low cost, but relatively low precision, suitable for occasions with low machining precision requirements, such as some simple teaching training equipment or the rough machining of parts with low precision requirements.
Closed-Loop Control CNC Machine Tools: A position detection feedback device is installed on the moving part of the machine tool to detect the actual motion position of the machine tool in real time and feed back the detection results to the CNC system. The CNC system compares and calculates the feedback information with the instruction signal, adjusts the output of the drive device, thereby achieving precise control of the motion of the machine tool. Closed-Loop Control CNC Machine Tools have higher machining precision, but the system structure is complex, the cost is high, and the debugging and maintenance are difficult, often used in high-precision machining occasions, such as aerospace, precision mold manufacturing, etc.
Semi-Closed-Loop Control CNC Machine Tools: A position detection feedback device is installed at the end of the drive motor or the end of the screw, detecting the rotation angle or displacement of the motor or screw, indirectly inferring the position of the moving part of the machine tool. Its control precision is between that of the open-loop and closed-loop. This type of machine tool has a relatively simple structure, moderate cost, and convenient debugging, and is widely used in mechanical machining.

 

VI. Applications of CNC Machine Tools in Modern Manufacturing
Aerospace Field: Aerospace parts have characteristics such as complex shapes, high precision requirements, and difficult-to-machine materials. The high precision, high flexibility, and multi-axis simultaneous machining capabilities of CNC machine tools make them key equipment in aerospace manufacturing. For example, components such as blades, impellers, and casings of aircraft engines can be precisely machined with complex curved surfaces and internal structures using a five-axis simultaneous machining center, ensuring the performance and reliability of the parts; large structural components such as aircraft wings and fuselage frames can be machined by CNC gantry milling machines and other equipment, meeting their high precision and high strength requirements, improving the overall performance and safety of the aircraft.
Automobile Manufacturing Field: The automobile industry has a large production scale and a wide variety of parts. CNC machine tools play an important role in the machining of automobile parts, such as the machining of key components such as engine blocks, cylinder heads, crankshafts, and camshafts, as well as the manufacturing of automobile body molds. CNC lathes, CNC milling machines, machining centers, etc. can achieve efficient and high-precision machining, ensuring the quality and consistency of the parts, improving the assembly precision and performance of the automobile. At the same time, the flexible machining capabilities of CNC machine tools also meet the requirements of multi-model, small-batch production in the automobile industry, helping automobile enterprises to quickly launch new models and improve their market competitiveness.
Shipbuilding Industry Field: Shipbuilding involves the machining of large steel structure components, such as ship hull sections and ship propellers. CNC cutting equipment (such as CNC flame cutters, CNC plasma cutters) can accurately cut steel plates, ensuring the quality and dimensional precision of the cutting edges; CNC boring milling machines, CNC gantry machines, etc. are used to machine components such as the engine block and shaft system of ship engines as well as various complex structural components of ships, improving machining efficiency and quality, shortening the construction period of ships.
Mold Processing Field: Molds are basic process equipment in industrial production, and their precision and quality directly affect the quality and production efficiency of the product. CNC machine tools are widely used in mold machining. From the rough machining to the fine machining of molds, different types of CNC machine tools can be used to complete. For example, a CNC machining center can perform multi-process machining such as milling, drilling, and tapping of the mold cavity; CNC electric discharge machining machines and CNC wire cutting machines are used to machine some special-shaped and high-precision parts of the mold, such as narrow grooves and sharp corners, capable of manufacturing high-precision, complex-shaped molds to meet the requirements of the electronics, household appliances, automobile, etc. industries.
Electronic Information Field: In the manufacturing of electronic information products, CNC machine tools are used to machine various precision parts, such as mobile phone shells, computer motherboards, chip packaging molds, etc. A CNC machining center can achieve high-speed, high-precision milling, drilling, engraving, etc. machining operations on these parts, ensuring the dimensional precision and surface quality of the parts, improving the performance and appearance quality of the electronic products. At the same time, with the development of electronic products towards miniaturization, lightweight, and high-performance, the micro-machining technology of CNC machine tools has also been widely applied, capable of machining micron-level or even nanometer-level small structures and features.

 

VII. Development Trends of CNC Machine Tools
High-Speed and High-Precision: With the continuous progress of materials science and manufacturing technology, CNC machine tools will develop towards higher cutting speeds and machining precision. The application of new cutting tool materials and coating technologies, as well as the optimization of machine tool structure design and advanced control algorithms, will further improve the high-speed cutting performance and machining precision of CNC machine tools. For example, developing higher-speed spindle systems, more precise linear guides and ball screw pairs, and adopting high-precision detection and feedback devices and intelligent control technologies to achieve sub-micron or even nanometer-level machining precision, meeting the requirements of ultra-precision machining fields.
Intelligentization: Future CNC machine tools will possess stronger intelligent functions. By introducing artificial intelligence, machine learning, big data analysis, etc. technologies, CNC machine tools can achieve functions such as automatic programming, intelligent process planning, adaptive control, fault diagnosis and predictive maintenance. For example, the machine tool can automatically generate an optimized CNC program according to the three-dimensional model of the part; during the machining process, it can automatically adjust the cutting parameters according to the real-time monitored machining state to ensure machining quality and efficiency; by analyzing the running data of the machine tool, it can predict possible faults in advance and carry out maintenance in time, reducing downtime, improving the reliability and utilization rate of the machine tool.
Multi-Axis Simultaneous and Compound: The multi-axis simultaneous machining technology will further develop, and more CNC machine tools will possess five-axis or more simultaneous machining capabilities to meet the one-time machining requirements of complex parts. At the same time, the compounding degree of the machine tool will continuously increase, integrating multiple machining processes on a single machine tool, such as turning-milling compound, milling-grinding compound, additive manufacturing and subtractive manufacturing compound, etc. This can reduce the clamping times of parts between different machine tools, improve machining precision and efficiency, shorten the production cycle, and reduce the production cost. For example, a turning-milling compound machining center can complete multi-process machining such as turning, milling, drilling, and tapping of shaft parts in a single clamping, improving the machining precision and surface quality of the part.
Greening: Under the background of increasingly strict environmental protection requirements, CNC machine tools will pay more attention to the application of green manufacturing technologies. Research and development and adoption of energy-saving drive systems, cooling and lubrication systems, optimization of machine tool structure design to reduce material consumption and energy waste, development of environment-friendly cutting fluids and cutting processes, reducing noise, vibration, and waste emissions during the machining process, achieving the sustainable development of CNC machine tools. For example, adopting micro-lubrication technology or dry cutting technology to reduce the amount of cutting fluid used, reducing environmental pollution; by optimizing the transmission system and control system of the machine tool, improving the energy utilization efficiency, reducing the energy consumption of the machine tool.
Networking and Informatization: With the development of industrial Internet and Internet of Things technologies, CNC machine tools will achieve a deep connection with the external network, forming an intelligent manufacturing network. Through the network, remote monitoring, remote operation, remote diagnosis and maintenance of the machine tool can be achieved, as well as seamless integration with the enterprise’s production management system, product design system, supply chain management system, etc., achieving digital production and intelligent manufacturing. For example, enterprise managers can remotely monitor the running state, production progress, and machining quality of the machine tool through mobile phones or computers, and adjust the production plan in time; machine tool manufacturers can remotely maintain and upgrade the sold machine tools through the network, improving the after-sales service quality and efficiency.

 

VIII. Conclusion
As the core equipment in modern mechanical machining, CNC machine tools, with their remarkable characteristics such as high precision, high efficiency, and high flexibility, have been widely applied in numerous fields such as aerospace, automobile manufacturing, shipbuilding industry, mold processing, and electronic information. With the continuous progress of science and technology, CNC machine tools are developing towards high-speed, high-precision, intelligent, multi-axis simultaneous and compound, green, networking and informatization, etc. In the future, CNC machine tools will continue to lead the development trend of mechanical manufacturing technology, playing a more important role in promoting the transformation and upgrading of the manufacturing industry and improving the industrial competitiveness of the country. Enterprises should actively pay attention to the development trends of CNC machine tools, increase the intensity of technology research and development and talent cultivation, make full use of the advantages of CNC machine tools, improve their own production and manufacturing levels and innovation capabilities, and remain invincible in the fierce market competition.