A CNC machine is a machine equipped with a program control system that can logically process programs specified using codes or other coded instructions.
It integrates modern machinery manufacturing technology, automatic control technology, and computer information technology, and uses numerical control devices or computers to partially or completely replace the manual control of various actions of general-purpose machine tools when processing parts. Such as starting, processing sequence, changing cutting amount, spindle speed change, tool selection, cutting fluid start and stop, etc.
It is a high-efficiency, high-precision, high-flexibility, and high-automation CNC equipment integrating light, machine, and electricity.
1. What is CNC machining?
In the beginning, we called this type of manufacturing Numerical Control. It is a technology that realizes automatic control of a certain working process by digital control. The parameters it controls are usually mechanical quantities such as position, angle, speed, and switching quantities related to the flow of mechanical energy.
In the early days of NC technology, due to technical limitations, its NC system had to use digital logic circuits to “overlap” the control system of NC machine tools. This NC system is called a hardware-connected NC system, or NC. The numerical control system can be subdivided into three stages: tube, transistor, and small scale integrated circuit.
With the development of the times, after the 1970s, the development and popularization of computer technology and microprocessors laid the foundation for the emergence and development of modern computer numerical control technology. Due to the powerful functions and strong control ability of small computer technology and microprocessors, people consider replacing the hardware logic circuits of the NC era with computer software program control. The numerical control technology based on this idea and technology is called computer numerical control technology ( CNC ).
In the early days of the CNC numerical control system, the use of computer software program control partially replaced the hardware logic circuit of the NC era. With the continuous development of microprocessor functions, a dedicated CNC numerical control system has begun to appear. This numerical control system is a dedicated numerical control system based on a powerful microprocessor, also known as a central processing unit (CPU). The system is essentially a dedicated small computer. At present, the numerical control system of this structure is widely used. In recent years, the CNC system has been developing towards the PC-based direction. This CNC system has the characteristics of openness, low cost, high reliability, and abundant software and hardware resources, which is the development trend of the future CNC system.
2. Development of CNC technology
Since its emergence, CNC technology has roughly gone through two stages and six eras of development.
Stage 1: Hardware Numerical Control (NC) stage. At this stage, limited by the development of technology, the digital logic control of the numerical control system is mainly formed by hardware connection, that is, the hard-wired system (Hard-Wired NC) is often referred to as numerical control (NC). With the development of electronic components, this stage has gone through about 3 eras of development, namely the first generation in 1952—the tube; the second generation in 1959—the transistor; the third generation in 1965—the Small scale integrated circuits. The hard logic CNC system with hardware connection in the first stage is basically eliminated at present.
Stage 2: Computer Numerical Control (CNC) stage. With the development of computer technology and its penetration into the field of numerical control, at the end of the 1960s, a direct numerical control system (DNC), also known as a group control system, in which a computer directly controls multiple machine tools appeared successively; Computer numerical control system (abbreviated as CNC) in which the computer software program replaces the hardware wiring logic circuit. The development of this stage is currently considered to have roughly experienced three eras of development, namely, the fourth generation characterized by minicomputers started in 1970; the fifth generation started in 1974 with microprocessors as the core; the PC-based computer started in 1990 (PC-Based) the sixth generation.
The specific expression of the development of the above 6 generations of CNC machine tools is:
- In 1952, the electronic tube components were used to form the logic components of the numerical control system.
- In 1959, transistor components and printed circuit boards were used, and a CNC machine tool with an automatic tool changer appeared, called a machining center (MC, MachiningCenter), which made the CNC device enter the second generation.
- In 1965, the third-generation integrated circuit numerical control device appeared, which was not only small in size, low in power consumption, but also improved in reliability and further reduced in price, which promoted the development of the variety and output of CNC machine tools.
- At the end of the 1960s, a direct numerical control system (DNC), also known as a group control system, was successively controlled by a computer to directly control multiple machine tools. The fourth generation is characterized by mini-computerization.
- In 1974, a microcomputer numerical control device (MNC) using a microprocessor and semiconductor memory was successfully developed, which is the fifth generation numerical control system.
- In the early 1980s, with the development of computer software and hardware technology, a numerical control device that can automatically program man-machine dialogue appeared; the numerical control device became more and more miniaturized and could be directly installed on the machine tool; the degree of automation of the numerical control machine tool Further improved, with automatic monitoring tool breakage and automatic detection of workpieces and other functions. In the late 1990s, the PC-Based intelligent numerical control system appeared, that is, the PC is the hardware part of the control system, and the NC software system is installed on the PC. This method is convenient for system maintenance and easy to implement. Networked Manufacturing.
3. The emergence and development of CNC machine
Machining using digital technology can be traced back to the 1940s and was realized by Parsons Corporation, a small aircraft industry contractor in the USA. When they manufacture the frame of the airplane and the rotor of the helicopter, they use the all-digital computer to process the data of the machining path of the wing, and take into account the influence of the tool diameter on the machining route, so that the machining accuracy reaches ±0.0381mm (±0.0015in), was the highest level at the time. In 1949, the company started joint research with the Massachusetts Institute of Technology (MIT), and successfully trial-produced the first three-coordinate CNC milling machine in 1952, which is the currently recognized symbol of CNC machine tools. This machine was an experimental machine, and by November 1954, on the basis of Parsons’ patent, the first industrial CNC machine was officially produced by the American Bendix Cooperation.
Since 1960, some other industrial countries, such as Germany and Japan, have successively developed, produced and used NC machine tools. The earliest NC machine tool that appeared and was used NC milling machine, because it can solve the curve or surface parts that are difficult to be performed by ordinary machine tools and need to be contoured. The early numerical control system used electronic tubes, which were bulky and high power consumption, so it was not popularized and used in other industries except in the military sector.
After 1960, point-controlled NC machine tools have developed rapidly. Because the numerical control system of point control is much simpler than the numerical control system of contour control, the numerical control milling machine, punching machine, and coordinate boring machine are developed in large quantities. According to statistics, 85% of the approximately 6,000 NC machine tools actually used by 1966 were point-controlled machine tools.
The machining center is one of the bright spots in CNC machine tools. It has an automatic tool changer, which can realize the processing of workpieces in one clamping and multiple processes. It was originally developed by Keaney & Trecker Corp. in March 1959. This kind of machine tool is equipped with taps, drills, reamers, milling cutters, and other tools in the tool magazine automatically selects the tools according to the instructions of the punched paper tape, and installs the tools on the spindle to process the workpiece through the manipulator. It reduces the time for loading and unloading parts on the machine and the time for changing tools. Today, machining centers have become a very important variety in CNC machine tools. There are not only vertical, horizontal, and other boring and milling machining centers for machining box parts, but also turning centers and grinding centers for rotating integral parts. cutting center, etc.
The early CNC system is a hardware-connected NC system, and its corresponding machine tool is called an NC machine tool. In the 1970s, the NC system entered the CNC era, and the CNC machine tools after that can be called CNC machine tools.
In 1967, the United Kingdom first connected several CNC machine tools into a flexible processing system, which is the so-called FMS. After that, the United States, Europe, Japan, etc. have also successively developed and applied.
In the 1980s, a flexible manufacturing cell (FMC) with 1 to 4 machining centers or turning centers as the main body, coupled with automatic workpiece loading and unloading and monitoring and inspection devices appeared in the world. This unit is low-investment, quick-acting, and can be left unattended for long periods of time alone or integrated into an FMS or higher-level integrated manufacturing system.
In the 1990s, the Computer Integrated Manufacturing System (CIMS), including market forecasting, production decision-making, product design and manufacturing and sales, was managed and controlled by computer integration. On the basis of and manufacturing technology, various isolated automation subsystems scattered in the product design and manufacturing process are organically integrated through computer technology to form an integration and intelligence suitable for multi-variety and small batch production to achieve overall benefits. manufacturing system.
To sum up, it can be seen that CNC machine tools have become one of the important components in the modern manufacturing production system, and it is also the basis for realizing computer-aided design (CAD), computer-aided manufacturing (CAM) and other modern manufacturing technologies.
4. Why choose CNC machining?
CNC machining is a fast, precise, and universal machining method, suitable for manufacturing any quantity of product orders, without the need to make a mold, that is economical.
5. Why choose DFM Rapid today?
We are a CNC machining China shop in Dongguan. We have 20 CNC milling and turning machines in our shop. We can offer you CNC rapid prototyping and low-volume CNC machining services for plastic and metal parts. Also, surface finish like anodized, powder coating is available.
Material Choice: Common metal materials on the market such as stainless steel, mild steel, aluminum, copper, brass, magnesium alloy, titanium alloy can be used for CNC machining. Plastics can also be CNC machined. Such as acetal, POM, ABS, Polycarbonate, PMMA, PEEK, and more.
What is the maximum part size your machine can handle?
Our maximum part size is 2000 x 600 x 600 mm, 78.7 x 23.6 x 23.6 in
What is the tolerance range that CNC machining can do?
It depends on the dimension of the parts. Normally our standard of tolerance is from +/-0.01mm to +/-0.15mm.
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