Created By:Vani Mathur | Created Date :15 March, 2023
Numerical control (also known as Computer Numerical Control and commonly referred to as CNC) is the automated control of machining tools (such as drills, lathes, mills, grinders, routers, and 3D printers) with the help of a computer. A CNC machine processes a piece of material (metal, plastic, wood, ceramic, or composite) to specification by following programmed coded instructions and without a manual operator directly controlling the machining operation.
A CNC machine is a powered maneuverable tool and often a powered maneuverable platform, both controlled by a computer according to specific input instructions. Commands are given to a CNC machine in the form of a sequential program of machine control commands such as G code and M code and then executed. The program can be written by a person or, much more commonly, generated by computer-aided graphic design (CAD) or computer-aided manufacturing (CAM) software. With 3D printers, the part to be printed is "sliced" before the instructions (or the program) are generated. 3D printers also use G-code.
CNC offers much higher productivity than non-computer aided machining for mass production, where the machine must be controlled manually (e.g. with devices such as hand wheels or levers) or mechanically with ready-made pattern guides (see pantograph mill). However, these benefits come with significant costs in the form of capital expenditures and job setup time. On some low-volume and prototyping jobs, a good machinist can finish parts to a high standard while the CNC workflow is still set up.
The resulting instructions are converted (by "post-processor" software) into the specific instructions needed for a particular machine to manufacture the part, and then loaded into the CNC machine.
Since several different tools (drills, saws, etc.) may need to be used for each particular component, modern machines often combine several tools into a single "cell". Other installations use multiple different machines with an external controller and human or robotic operators moving the component from one machine to another. In each case, the series of steps required to manufacture any part is highly automated, resulting in a part that closely resembles the original CAD drawing.
The motion controls multiple axes, usually at least two (X and Y), and a tool spindle moving in Z (depth). Tool position is driven by direct drive stepper motors or servomotors to allow for high precision movement, or in older designs by motors via a series of reduction gears. The controls work as long as the forces are kept small enough and the speeds are not too high. On commercial metalworking machines, closed loop control is standard and required to provide the required accuracy, speed and repeatability.
As the controller hardware evolved, so did the mills themselves. One change was to enclose the entire mechanism in a large box for safety (with safety glass on the doors to allow the operator to control the operation of the machine), often with additional ones Safety interlocks to ensure the operator is far enough away from the work station. part for safe operation. Most of the new CNC systems built today are 100% electronically controlled.
CNC-like systems are used for all processes that can be described as movements and operations. These include laser cutting, welding, friction welding, ultrasonic welding, flame and plasma cutting, bending, spinning, drilling, nailing, gluing, fabric cutting, sewing, tape and fiber laying, milling, assembling and sawing.
The first NC machines were built in the 1940s and 1950s, based on existing tools modified with motors that moved the tool or part to follow points entered into the system on punched tape. These early servomechanisms were quickly augmented with analog and digital computers, giving rise to modern machine tools.