CNC (Computer Numerical Control) machines are utilized extensively in metalworking industries to cut, shape, and form various metal components with high precision and efficiency. When it comes to cutting metal on CNC machines, several processes can be employed, including milling, turning, drilling, and threading. This article delves into the intricate details of how CNC machines cut metal, unraveling the technology that underpins this crucial aspect of modern machining.
The Development History of CNC Machine
With the continuous progress of social production and science and technology, various new industrial products are emerging one after another. As the foundation of national industry, the mechanical manufacturing industry’s products are becoming increasingly precise and complex, especially in the fields of aerospace, navigation, military and other mechanical parts that require higher precision, more complex shapes, and often smaller batches. Processing such products requires frequent modification or adjustment of equipment,
Ordinary machine tools or highly specialized automated machine tools obviously cannot meet these requirements. Meanwhile, with the increasing market competition, enterprises urgently need to further improve their production efficiency, improve product quality, and reduce production costs.
A new type of production equipment – CNC machine tools – has emerged.
Parsons Corporation officially accepted the commission and collaborated with the Servo Mechanism Laboratory of the Massachusetts Institute of Technology to successfully produce the world’s first experimental prototype of a CNC machine tool in 1952. In 1959, Keaney&Trecker successfully developed the Machining Center for the first time in the United States.
The Working Principle of CNC Machine
CNC machine tools are mechanical equipment that perform machining operations through computer control, and their working principles cover multiple key aspects. The following is an overview of the basic working principles of CNC machine tools:
1. CAD/CAM Design and Program Generation
The process of cutting metal begins with Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM). In the CAD environment, engineers design a three-dimensional model of the desired part. CAM software is responsible for converting the design into a machine-understandable cutting path. The generated program includes crucial information such as tool paths, cutting speeds, feed rates, and more.
2. CNC Control System
The generated CAM program is transmitted to the control system of the CNC machine tool. The CNC control system serves as the brain of the CNC machine, interpreting the program instructions and translating them into actual movements. This system typically consists of a controller, servo system, and input devices. The controller interprets the CAM program and converts it into control signals for axis motion.
Within the CNC program, a thread size chart can be incorporated as a reference. This chart includes information about standard thread sizes, pitch, and other relevant dimensions. By integrating this chart into the program, the CNC machine can automatically select the appropriate cutting tool and machining parameters based on the desired thread size.
Thread Size Chart (inch/mm)
3. Work Coordinate System
To accurately position the cutting tool and workpiece, CNC machine tools utilize a work coordinate system. This system establishes a three-dimensional coordinate system, enabling precise tool positioning along the X, Y, and Z axes. The CNC control system uses this information to ensure accurate cutting.
4. Motion Control
One of the key components of CNC machine tools is motion control. Through the servo system, CNC machines can accurately control the motion of the tool along the X, Y, and Z axes. This includes linear interpolation and circular interpolation, ensuring that the tool follows the predetermined path accurately.
5. Cutting Process
With everything set up, the CNC machine tool initiates the cutting process. The cutting tool engages the metal workpiece, following the pre-determined toolpath with precision. The CNC control system controls the cutting speed, feed rate, and depth to achieve the desired results.
6. Real-time Monitoring and Feedback
Advanced CNC machine tools are equipped with real-time monitoring systems that track key parameters during the cutting process. Sensors and feedback mechanisms ensure cutting quality and make adjustments if needed. This real-time feedback helps improve production efficiency and part quality.
8. Post-Processing and Finishing
Once the cutting process is complete, post-processing steps may include deburring, cleaning, or additional machining for fine-tuning. CNC machine tools can be programmed to execute these post-processing steps, ensuring a comprehensive and refined end product.
The Benefits of CNC Machine for Metal Machining
The widespread application of Computer Numerical Control (CNC) machine tools in metal processing brings numerous advantages, ranging from enhanced precision to improved production efficiency. Here are some notable benefits of CNC machine tools in metal machining:
1. High Precision
CNC machine tools control tool movement through computer programs, achieving highly precise machining. This ensures the accuracy and consistency of metal parts, surpassing the precision levels achievable through manual operations.
2. Complex Part Machining
CNC machine tools can effortlessly handle the machining of parts with intricate shapes. Program designs allow precise control of tool movement in various directions, enabling highly complex cutting operations.
3. Automated Production
CNC machine tools realize a high level of automation in the production process. Once an appropriate program is written, the machine can run continuously, reducing the need for manual operations and increasing production efficiency.
4. Production Flexibility
The flexibility of CNC machine tools allows them to adapt to the production of parts with different shapes and specifications. By simply modifying the program, it is possible to quickly switch to production modes for different parts, reducing changeover time and production costs.
5. Reproducibility and Consistency
As operations are controlled by computer programs, CNC machine tools maintain a consistent quality level in mass production. Cutting parameters for each part can be accurately replicated, ensuring product consistency.
6. Shorter Machining Cycles
CNC machine tools typically operate at higher speeds, reducing machining cycles. This is crucial for meeting urgent orders or enhancing overall production efficiency.
7. Reduction of Human Errors
Since CNC machine tools primarily rely on pre-programmed instructions, the likelihood of human errors is minimized. This increases the reliability and stability of the manufacturing process.
Applications:
Beyond the artistic process of metal cutting, CNC machine tools find applications across diverse industries. From aerospace and automotive to medical device manufacturing, their adaptability shines. The advantages of CNC machining, including high precision, automation, flexibility in production, and reduced human errors, have elevated these tools to the forefront of modern manufacturing, where efficiency and quality take center stage.
FAQ
Generally, CNC machines are capable of cutting materials ranging from thin sheets (as thin as a fraction of a millimeter) to thick blocks or plates measuring several inches in thickness. High-powered CNC machines with specialized cutting tools can handle thicker materials, while others may be limited to thinner materials.
The CNC metal process, short for Computer Numerical Control, involves the use of computerized systems to control machining tools and equipment for shaping and cutting metal components with precision and accuracy. This process typically begins with the creation of a digital design or model using computer-aided design (CAD) software. The design is then translated into instructions, or G-codes, which are fed into the CNC machine. The CNC machine interprets these instructions to precisely control the movement and operation of cutting tools, such as drills, mills, or lathes, to shape the metal workpiece according to the desired specifications.
