Since it first appeared in 1972, computer numerical control, also known as computerised numerical control, has brought nothing but major benefits to the industries that use it. The importance of CNC today is such that almost all conventional machine tools have adopted it in their systems to achieve greater precision and efficiency and to speed up production.
What is CNC?
CNC refers to a system of automated machine tools that operate through programmed commands held in a storage system (a computer). This is precisely what sets CNC apart from conventional machines, which are operated by handwheels or levers. Although it is a revolutionary technology and the most advanced in the industry, CNC was invented in the twentieth century. The first machines date from the 40s and 50s, but advances in technology gradually adapted them to analogue and digital equipment until CNC officially emerged in the 70s.
This was made possible by the falling cost of processors and their miniaturisation. It was then that the terms computer numerical control and computerised numerical control came into use.
How computer numerical control works
On every machine tool, parts are machined using a coordinate system, which defines the path the cutting tool must follow. With CNC, this is done by a computer program, which in turn is executed by the machine's computer. The movement of the axes on a CNC machine is made possible by control loops made up of linear scales (encoders) and the central unit. Each of the machine's axes is controlled by these loops.
Each machine tool works on different coordinates. A lathe, for example, uses the X and Z axes. The first allows longitudinal movements of the carriage, while Z handles the cross movements. Milling machines, on the other hand, add a third axis, Y, which allows vertical movements.
The importance of CNC
The importance of CNC for machining workshops lies in its ability to carry out multiple tasks in a short time and with minimal human intervention. Computer numerically controlled machines make it possible to speed up production processes, which means shorter lead times and, of course, lower product prices and labour costs. CNC also allows a single operator to run several machine tools at the same time.
Beyond these benefits, CNC makes it possible to machine highly complex parts that could not have been produced on conventional machines or that would have been very expensive to machine. Before CNC, for example, a part that needed several machining operations had to go through different machines: a lathe to shape and drill it, and then a grinding machine. And with very small parts requiring high precision, the results might not be as intended, or one operator might have to spend a long time machining the part, which meant high production costs. With CNC, everything can be done on a single machine.
CNC is not only used in the metalworking industry for precision machining, however. The technology is also used to make parts in other industries, such as woodworking.
Features and benefits of CNC
Greater precision
Because CNC works with software for programming, the results are far more precise than with conventional machine tools operated manually. And since the processes are controlled by this software, they can be completed quickly and with fewer errors on the parts.
In addition, the machines' CAM and CAD software can repeat the same process thousands of times with the same level of precision. In series production, for example, there is no need to reconfigure the machine again and again: it stores what it has to do and always repeats the process exactly.
The importance of CNC for factory safety
The machines work almost entirely automatically, so operators are not exposed to the machines, which improves safety and reduces the risk of accidents. Many allow the integration of robotic loading arms, so the operators' only task would be programming the equipment.
Less waste
Computer numerically controlled machines work by metal cutting, but they have the advantage of reducing metal waste. This is because these machines are designed with systems for managing the chips, which remove this waste automatically and therefore more cleanly. Finally, CNC machines can separate the different types of chips so that they can be reused.