Manufacturing automation is an extremely efficient way to produce goods. This approach has become ever more popular with the advent of innovative technologies in recent years. A concept that helps machines work properly is called computer numerical control, abbreviated as CNC (computer numerical control). Let's learn about what CNC is!
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1. What is CNC?
What is CNC?
CNC stands for "Computer Numerical Control" meaning computer numerical control, is a concept that indicates how machine tools work based on how those tools work. Specific coded instructions are sent to what is called an internal microprocessor in the control system of the machine tool. This microprocessor basically acts as a mini computer that can receive information. This internal processor accepts the informative instructions it receives, interprets how they are executed, and then physically performs a desired function for a machine. The big benefit of CNC is that these pre-coded functions can be much more specific - and done with much more precision - than what someone can manually do with a machine tool.
Of course, computer numerical control is primarily intended to help automate processes, make them more efficient, and reduce - or even eliminate - the amount of manual labor involved in their execution. With that said, CNC is often used with computer-aided design (CAD) programs and computer-aided manufacturing (CAM) programs. Commonly used CNC machines include lathes, mills, routers, plasma cutters, waterjet cutters, and grinders.
2. Importance of CNC in manufacturing
Computer numerical control is an extremely high-tech and important process in today's manufacturing world. Skilled engineers must program the files used by the microprocessor in a machine tool to make a machine work properly and efficiently. It's amazing how quickly so many different goods can be produced, but CNC technology is the key backbone that sets these processes apart.
Importance of CNC in manufacturing
3. CNC system components
A CNC system consists of a human-machine interface (HMI), a programmable numerical controller, an integrated feedback device, a servo and motor actuator as well as a spindle and motor actuator.
Digital controller
The numerical controller executes the CNC program software, which includes part program translator, trajectory generator, motion control and discrete logic program. Current numerical controllers provide features, such as object contours, circles, linear, spirals, and polynomial interpolation, and conversational programming. Conversation programs calculate the geometry of a part from a few known points and contain canning cycles so that a part program can be copied from available data directly on the blue print. .
System software embedded in the digital controller provides precise control in advance of servo drives and spindles. It communicates with the servo actuator to coordinate motor shaft speed and position. The drives provide the position commands and torque control necessary for speed regulation. Such embedded software is usually proprietary and is included as part of the vendor's hardware revenue.
CNC system components
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Motor and main bearing
The spindle rotates the tool in milling applications and the work piece in turning applications. Many machine tools have multiple spindles to provide a wide range of operations. Typical multi-spindle applications mount a large horsepower spindle in a relatively low speed range for material removal in the roughing stage and use a low horsepower high speed spindle for the finishing stage. The main shaft motor is usually a 3-phase AC squirrel cage induction motor. Each spindle motor requires a separate variable speed AC actuator with integrated power supply.
Variable speed (variable frequency) AC drives are available with three control modes: constant volt/hertz control, open loop sensorless flux vector control and closed loop flux vector control . While constant volt/hertz actuators were widely used in older CNC systems, flux vector actuators are more common in newer CNC systems. There is a clear distinction between these drive technologies from an application perspective. While volt/hertz actuators operate with relatively constant torque, since torque is proportional to volt/hertz, flux vector actuators provide better control over speed and acceleration, as they change torque based on the applied load. They provide higher torque, which is often required at low speeds. Drives
The main module is usually provided as a module ready to be installed into the control panel.
Servo Drive and Motor
The accuracy of a CNC system depends on its ability to measure changes in position along its axis and drive the motor under full torque and speed to target positions. The servo drive and motor, which performs position control along the axis, is an integrator, suitable for a CNC system. Servo system features four-quadrant operation, speed and current feedback, high acceleration torque, dead band-free speed control, and quick and precise accuracy to meet changing needs speed.
Two types of servo motors are DC Brush and brushless servo motors. The brush type servo motor converts DC power to the field winding through a harmonic converter. The brushless servo motor has a permanent magnet rotor and depends on an electronic servo actuator to provide switching for the field windings. Brushless AC servo system uses sine wave while DC brushless servo system uses trapezoidal wave. AC systems are widely used because of better low-speed operation, reduced motor locking, and reduced torque ripple. The servo drive processor is usually a Digital Signal Processor (DSP) and receives commands from the numer-ical controller.
OS HMI
Part programming and discrete logic programming are performed from the HMI station and sent to the CNC controller. While proprietary OS-based HMI stations are still in use, Windows-based PC-based HMIs are gaining in popularity.
PC-based HMI stations make it possible for CNC systems to use PC-based CAD/CAM and other graphics software to program the CNC sub-troller automatically. In the case of proprietary CNC systems, even though they can use PC-based HMIs, digital controller CPUs are still proprietary. Programming of the CNC CPU is done by linking the PC HMI to the CNC controller hardware.
On the other hand, an open CNC machine uses a PC-based HMI as well as a controller that uses PC-based hardware. Such open CNC machines can exchange information with third-party PC-based software and communicate with other equipment using RS232 and standard LANs such as Ethernet. The open CNC system separates the HMI from the programming software. However, most open CNC machines retain a control system that runs on a proprietary Real-Time Operating System (RTOS) to control the movement of the axes.
This article helps you understand what CNC is and the content about CNC. Hope this article will answer some of your questions.
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