What is CNC Machining?
CNC machining is a subtractive manufacturing technique. Using a variety of cutting tools, material is removed from a blank part or workpiece until the desired shape is achieved. CNC stands for Computer Numerical Control. This means that computer software is used to control the movement and operation of the machine tool. These CNC machines include machining centers, turning and milling centers, EDM wire cutting machines, thread cutting machines, and so on. Currently, the vast majority of machine shops use CNC machining technology. The coordinates of the position of the workpiece in the Cartesian coordinate system (X, Y, Z) are converted into a program language through programming. The CNC machine controls the axes of the CNC machine by recognizing and interpreting the program language. Material is automatically removed as needed to obtain a finished workpiece. CNC machine tools process workpieces in a continuous manner. It is suitable for large quantities and complex shaped workpieces.
CNC Machining: A Brief History
CNC machining has a long history. As early as about 1760, the British engineer John Wakefield invented the first mechanical lathe, which is regarded as the beginning of the machining industry and greatly promoted the development of the industrial revolution. This is regarded as the beginning of the machining industry, which greatly promoted the development of the industrial revolution. 1950s, CNC technology began to be applied in the field of machining. This marked a new stage in CNC machining, which greatly improved machining accuracy and efficiency.
With the development of science and technology and the integration of the global economy, the manufacturing industry is faced with rapidly changing market demand. CNC machining can meet the demand for small batch, multi-species production. Reduce the production preparation, machine tool adjustment and process inspection time, improve production efficiency and reduce costs. In the 21st century, information technology has developed rapidly, and intelligent manufacturing and Industry 4.0 have emerged. Through the application of intelligent technology, the production process is more intelligent and efficient. This brings new opportunities for CNC machining.
How Does CNC Machining Work?
CAD Programming
CAD software enables designers to digitally create accurate models of parts and products. With CAD, designers can detail the geometry, dimensions and features of a part, providing a clear and accurate blueprint for subsequent machining processes. In CNC machining, CAD-generated design files can be imported directly into CAM software, providing the basis for tool path planning and machining process development.
Calibration program
Calibrating the CNC program is critical to ensure accurate and safe machining. Common methods of calibration include simulation using CNC simulation software. Simulate the actual machining process in the software. Check that the tool paths and cutting parameters are reasonable and that there are no collisions or other problems.
Tool Selection
Choosing the right tool is an important factor in achieving good machining results with CNC Machining. According to the cutting performance of the part material to select the tool. Processing of high-strength steel, titanium alloy, etc., it is appropriate to use good wear resistance indexable carbide tools. When roughing, choose a tool with good rigidity and low precision. When semi-finishing and finishing, choose tools with high durability and high precision.
Mounting the work piece
To ensure that the positioning datum coincides with the design datum to reduce the positioning error. For the hardness of the work piece and large processing volume, the fixed strength should be large. For small hardness of the work piece, the fixing force should be moderate to prevent the work piece from extrusion and deformation. After clamping, consider the force point of the clamped fixed work piece. Ensure that the position of the work piece does not move during processing. Also follow the six-point positioning principle. Limit the horizontal movement of the work piece in the X, Y and Z directions and the rotation around these three axes.
Adjusting parameters
When machining for the first time, take some safety measures to avoid losing control of the CNC machine. Utilize the single program segment function, feed speed multiplier function, and CNC machine lock function to verify machine operation. When setting parameters, comprehensive consideration should be made according to the material of the machining work piece, the material and size of the tool, and other factors. For materials with higher hardness, reduce the cutting speed and feed appropriately. For smaller tool diameters, reduce the depth of cut accordingly.
Start machining
CAM software translates CAD designs into actual machining instructions, guiding the CNC machine to perform precise cutting, drilling, milling, etc. CAM software can automatically plan tool paths based on the CAD model of the part and the machining requirements. CAM software can simulate and validate the machining process. Before the actual machining, the simulation can predict the possible collision, over cutting and other problems. Timely adjustment of machining parameters and tool paths can reduce scrap rates and machine downtime.
Checking the quality
The quality inspection criteria for CNC Machining cover a number of areas. The first is surface roughness, which is checked using external A-gauge standards. Next is dimensional inspection, where the dimensions of the product are accurately measured using an external dimension tester. Structural inspection is also critical, checking the machining accuracy and structure of the part by direct measurement. Polishing is also checked to ensure the surface finish. Finally, comprehensive performance testing is performed. This includes tensile, thrust, and fatigue tests. The mechanical and quality performance of the product is evaluated to ensure that the final product meets customer requirements.
Post-processing
First, the finished work piece is cleaned. Then quality inspection is carried out. Then surface treatment is carried out. For work pieces that need to be assembled, carry out assembly operations and final debugging and inspection. In the whole post-processing process, the relevant process standards and quality requirements should be strictly followed.
Types of CNC Machines
CNC machines according to CNC trajectory can be divided into: point control CNC machine tools, linear control CNC machines and contour control CNC machine tools.
CNC machines according to the servo system control is divided into: open loop system, semi-closed loop system and full closed loop system.
CNC machines according to the number of linked axes can be divided into: two-axis linkage, two-axis semi-linkage, three-axis linkage, four-axis linkage and five-axis linkage.
CNC machines can be divided into: horizontal machining centers, vertical machining centers, universal machining centers and composite machining centers according to the location of the spindle and table.
CNC machines can be divided into: metal cutting, metal molding, special processing and other types according to the process use.
Materials Used in CNC Machining
Plastics
There is a wide variety of plastic types commonly used in CNC machining. ABS plastic, for example, is commonly used in the manufacture of electronic housings, household appliances, and other products. Nylon plastics, often used in medical devices. Polycarbonate plastics are used in fluidic devices or automotive glass, etc. POM plastics are ideal for making high-precision plastic parts, and PTFE plastics are often used as linings or inserts in electrical insulators and components.
Composites
Composite materials are widely used in CNC Machining. For example, in the aerospace field, the composite blades of aircraft engines require machining because of the large profile error after hot press molding. In automotive manufacturing, composites are also used, for example, in the manufacture of lightweight parts.
In the field of electronics, such as laptop computer design, in order to achieve high strength, low weight and other purposes, will be used in the combination of composite materials of different materials, the combination process involves CNC machining.
Wood
Wood materials used for CNC machining are easy to cut and shape and are often used in industries such as furniture manufacturing and construction. In the actual processing, according to the characteristics of wood CNC machining, milling elements, material properties, etc., you need to reasonably select the technical parameters of CNC machining tools, angle parameters, structural form and cutting amount.
Metals
Materials commonly used for CNC machining include aluminum, stainless steel, carbon steel, brass, titanium, magnesium, monel and other metals. As well as aluminum alloy 6061, Q235 steel, SUS304 steel and so on. Aluminum material processing speed, light weight, non-magnetic, corrosion-resistant and inexpensive. It is widely used in the production of aircraft components, automotive parts, bicycle frames and food containers. Stainless steel has excellent strength and corrosion resistance because it is unaffected by most stains and rust. Used in many applications from surgical equipment to electronic hardware.
Carbon steel is available in a variety of formulations and is often used in CNC machining for its durability, safety and affordability. Brass is easy to work with, has a smooth, clean surface, and is often used in the manufacture of medical equipment, consumer products, and more. Titanium is heat- and corrosion-resistant and is used in medical implants, aircraft components, jewelry and more. Magnesium is one of the lightest structural metals with excellent machinability and is used in a variety of industrial applications.
Advantages of CNC Machining
High precision and consistency
Typical accuracy for CNC machine tools has reached 2 to 4 thousandths of an inch, or 0.05 to 0.10 mm, with repeatability close to or better than 8 thousandths of an inch, or 0.02 mm. This means multiple identical parts can be easily produced with the same accuracy and consistency, ensuring consistent processing quality. CNC machining centers ensure machining accuracy mainly through various measures.
First of all, the accuracy of the equipment itself is very important, including machine tools, cutting tools and measuring equipment, all need to meet high standards. Reasonable process design is also key, such as carefully selecting tools and determining appropriate cutting parameters. Tool compensation is necessary and performed regularly to cope with the impact of tool wear on accuracy. The correct choice of work piece clamping method and position can ensure the stability of the work piece during processing and avoid a decrease in accuracy due to vibration or displacement. Temperature control is equally important. A stable working environment temperature or the use of thermal deformation compensation technology can effectively reduce dimensional errors caused by temperature changes. In addition, the operator’s skill and experience also have a significant impact on accuracy, and regular training is required to improve their skill and knowledge levels. For example, in the aerospace field, the precision requirements for parts are extremely high. Through the above measures, CNC machining centers can accurately process parts that meet strict standards.
Automation and high efficiency
CNC machining center has a high degree of automation, which can realize automated production, reduce manual intervention and reduce labor costs. When it comes to efficiency, CNC machining centers offer significant advantages. It can effectively save maneuvering time, move quickly to shorten the time of idle stroke, has a larger range of feed amount, can effectively select reasonable cutting amount, and can generally increase production capacity by 3 to 5 times.
The realization of automated production by CNC machining centers is an important breakthrough in modern manufacturing. By using advanced control systems and intelligent programming software, a high degree of automation in the processing process can be achieved. In practical applications, some companies have introduced automated production lines and connected multiple CNC machining centers to achieve one-stop automated processing from raw materials to finished products. For example, in the field of automobile parts manufacturing, through automated production, parts of various complex shapes can be produced quickly and accurately, meeting the needs of mass production.
To save maneuvering time, CNC machining centers employ a variety of strategies. Optimizing the machining program is one of the keys. By rationally arranging tool paths and cutting parameters, unnecessary idle strokes and repetitive actions can be reduced, thereby significantly shortening the machining time. The use of high-speed cutting technology is also an important means to increase cutting speed and feed speed, and greatly improve processing efficiency while ensuring processing quality.
Versatility and adaptability
CNC offers remarkable versatility and adaptability. In modern manufacturing, CNC technology is widely used in various fields, showing strong performance and advantages. In terms of adaptability, CNC systems can quickly adjust processing parameters and paths through programming to adapt to different part designs and production batches. For small-batch, customized production, CNC can respond flexibly and quickly switch production tasks.
With the continuous advancement of technology, CNC equipment has become more intelligent and can realize automated production monitoring and quality inspection, further enhancing its ability to adapt to complex production environments and high-quality requirements. Whether it is high-end fields such as aerospace, automobile manufacturing, medical equipment, or the general mechanical processing industry, CNC plays an irreplaceable role and has made important contributions to improving production efficiency, ensuring product quality, and reducing production costs.
Common Applications of CNC Machining
Aerospace
In the aerospace industry, CNC machining reduces the possibility of human error by automating the manufacturing process and shaping strong yet lightweight specialty metals within extremely tight tolerances for aerospace components. It can manufacture high-precision, high-performance parts, such as spacecraft parts, aircraft fuselage structures and engine parts. In spacecraft manufacturing, small errors can have serious consequences, and the high precision of CNC machining ensures the reliability of parts. For components with complex shapes such as aircraft engine blades, CNC machining can accurately shape their shapes to meet the needs of working in high-temperature and high-pressure environments. At the same time, CNC machining can also process parts that meet the characteristics of aerospace materials to ensure their strength and lightweight.
Automotive
In the field of automobile manufacturing, CNC machining is widely used. From the processing of key components such as engine blocks and crankshafts to the manufacturing of body sheet metal and interior parts, CNC machining is inseparable. For example, engine parts require high-precision machining to ensure performance and reliability, and CNC machining can achieve this. In car body manufacturing, complex curves and shapes require precise machining, and CNC machining can ensure the appearance quality and aerodynamic performance of the car body. In addition, parts of the car interior, such as the center console panel and the seat adjustment mechanism, are also processed by CNC to achieve high precision and good texture.
Electronics
CNC machining has irreplaceable advantages in the precision machining of electronic components. For example, in the manufacture of circuit boards, CNC machining enables precise drilling and milling to ensure that circuit connections are made accurately. In the production of electronic components such as resistors and capacitors, CNC machining can accurately control the size and shape to ensure stable performance of the components. For high-precision components such as camera modules, CNC processing can produce extremely small and complex structures to meet the needs of high-definition imaging. In addition, in the processing of sensitive components such as sensors, the high precision and stability of CNC processing can ensure its measurement accuracy and reliability. For example, pressure sensors in automotive electronics can achieve micron-level accuracy through CNC processing to ensure the stable operation of the automotive system.
Tips for Optimizing CNC Machining Processes
Improve cutting volume to improve machining efficiency
Improving cutting volume is one of the important ways to improve machining efficiency. Cutting quantity mainly includes cutting speed, feed and back draft. Increasing the cutting speed can significantly reduce the machining time. In mass production, it can significantly improve the overall productivity.
Improve the structure of parts process ability
A variety of measures can be taken when designing parts. For example, it is possible to improve the standardization of parts, the generalization of components, and the serialization of products. Reduce the complexity of design and manufacturing by making full use of established processes and standardized parts. Adopt parts with simple surface geometry and arrange them in the same plane or on the same axis.
Optimize the programming method
Reduce the number of loops by executing multiple iterations side by side through loop expansion in C programming. Use loop merging to combine multiple loops into one to improve program efficiency. Focus on code optimization to avoid repeated calculations and reduce unnecessary calculation overhead.
The Future of CNC Machining
In the field of new energy, CNC machining plays an important role. Taking new energy vehicles as an example, the efficient, high-precision and high-stability machining of its components is crucial for improving product performance and production efficiency.CNC machining technology makes rapid prototyping and manufacturing of complex automotive parts possible, and can meet the strict requirements of new energy vehicles on components. The vast majority of automotive parts, such as various rotating shafts, rotary shafts, gearboxes, gears, wheel hubs, brake drums, mechanical shafts, threads, etc., are produced by CNC machining.
CNC machining is rapidly developing in the direction of intelligence. Intelligence means that CNC systems are capable of autonomous learning, adaptive control and automatic optimization of the machining process. For example, some advanced CNC machining systems use optimization algorithms to automatically optimize parameters according to the machining situation, improving machining efficiency and quality. At the same time, the new generation of CNC systems also introduced a fault diagnosis system, which can automatically detect and diagnose machine tool failures and improve maintenance efficiency. In the intelligent manufacturing process, CNC systems can be interconnected with other intelligent devices to analyze machining data in real time and provide a basis for decision-making.
Common Challenges in CNC Machining
CNC machining has broad development prospects in the future, but it also faces a series of challenges. From the perspective of prospects, with the continuous advancement of smart manufacturing and Industry 4.0, CNC technology will become one of the key technologies for the digital transformation of the manufacturing industry. However, CNC machining also faces many challenges. The technical threshold is high, and operators need to have rich professional knowledge and operating experience, while technical talents are relatively scarce in the industry. At the same time, the CNC machining industry may lack appeal to young people, resulting in a shortage of talent pools.
In addition, the training system is imperfect and some areas lack complete training resources, making it difficult for people interested in working in this industry to obtain systematic and comprehensive training. In terms of material processing, high hardness and high brittleness materials such as silicon nitride ceramics and silicon carbide ceramics bring difficulties to CNC processing and require special tools and processing strategies. Moreover, as market competition intensifies, companies are facing pressure to reduce costs, improve efficiency and ensure quality, and need to continuously invest in technology upgrades and equipment updates.
CNC Machining vs. Traditional Machining
Traditional machining is usually based on manual operations, such as hand engraving and milling machine machining. Machining accuracy and efficiency are affected by the operator’s skill level and experience. CNC machining is a relatively simple process. CAD drawings are imported into CAM software for machining path planning and G-code generation. The G-code is then transmitted to the CNC machine for machining, which has a higher degree of automation.
In terms of machining accuracy, CNC machining can achieve a much higher level of precision. In some process areas it can even reach the micron level, whereas traditional machining is usually only able to guarantee a lower level of precision. In terms of repeatability and stability, CNC machining is better and ensures consistent results. The scope of production is different, traditional machining is usually suitable for small batch production or personalized products, CNC machining is more suitable for mass production.
Case Studies
Dawang Metals has shown unique process innovation in CNC machining. It has carried out in-depth research and improvement in tool path optimization, cutting parameter selection, and work holding design, etc. By optimizing the tool path, Dawang reduces the empty stroke of the tool and improves the machining efficiency. In terms of cutting parameter selection, after a large number of experiments and data analysis. Dawang found the most suitable combination of parameters for different materials and machining requirements, which improved the machining quality and tool life. Dawang designed a unique work holding fixture, which can clamp the work piece more stably and reduce the vibration and displacement during machining, so as to ensure the machining accuracy. Dawang’s technological innovation not only enhances its own competitiveness, but also provides useful references for the development of the whole CNC machining industry. Dawang’s process innovation not only enhances its own competitiveness, but also provides useful reference for the development of the entire CNC machining industry.
Choosing the Right CNC Machining Service
Dawang Metals has a complete CNC machining workshop and 26 CNC machining centers for efficient production. A professional team of engineers conducts technical research and development and production control. The workers in the CNC workshop have many years of working experience, and they receive regular professional training and practical guidance. Dawang’s CNC machining workshop has served domestic and foreign customers for many years and has gained high trust from customers. If your product requires high-volume, efficient machining, please contact us.
