Metalworking on CNC Machines

Metalworking on CNC machines is indispensable where a large number of products with high processing accuracy are required. In addition, CNC machines provide high repeatability of the products.

Such metalworking is becoming more and more popular, but this does not mean that only positive aspects are inherent in it. To better understand what is metalworking on CNC machines, we will tell you about the principle of operation of such equipment and the features of the processes.

The device and principle of operation of a CNC machine for metalworking

CNC machines are controlled by a specially created computer program. Before the advent of CNC, they were controlled manually. Now the computer drives the machine through servos. Human participation in equipment control is practically not required, only for its launch.

CNC (Numerical Control) is control carried out by a computer. It can be considered that CNC machines are a kind of robotic devices.

Metalworking using such equipment is the manufacture of parts under the guidance of a computer, or rather, a special program. Before the advent of CNC, machines had a hydraulic system that stamped products according to a template. The new systems allowed for increased control at all stages of work, for example, the spindle speed or starting the cooler and, of course, the movement of the machining center. Equipment with this control made the job of mass production much easier.

There are many kinds of CNC machines in operation now. These are 3D printers, and routers, and devices for water-jet metalworking, as well as electrical discharge, etc. Let’s consider the principle, as well as the stages of their work.

Specialists write programs for CNC machines using one of the programming languages ​​- G-Code. There are two ways to write programs: working from scratch or using software that can convert a CAD drawing of a product into G-code.

In the recent past, CNC machines, due to their high cost, were used mainly in industry. However, the market is now filled with a lot of affordable equipment. Professionals and amateurs are happy to use them not on an industrial scale, but for personal purposes.

Data input device

It is used to introduce a program to the hardware. Three main types of such devices are now used: these are punched tape and magnetic tape readers, as well as a computer that works through the RS-232-C port.

Machine control unit (BUS)

It is considered the center of the machine and has full control over it. BUS performs the following functions:

• Reading all codes coming to the control unit.
• Decode codes.
• Spiral, linear, circular interpolation in order to create signals (commands) with the help of which the axis moves.
• Communication to the amplifier circuits of the motion commands that control the axle mechanisms.
• Receiving and responding to messages about the speed and location of the drive axes.
• Additional functions, for example, turning on / off the cooler, as well as the spindle, tool change.
• Actuating mechanism.

CNC machines are equipped with a spindle and table. They control speed and position. They are controlled in different planes: the spindle – along the Z axis, and the table – along the X and Y axes.

Drive system

Includes ball screw bearing (ball screw) amplifier circuits, drive motors. The BUS using signals transmits information about the axes, their speed and position to the amplifier circuits. After that, the signal strength increases to bring the drive motors rotating the ball screws into operation. This is done in order to adjust the desktop in the desired position.

Feedback system

It is a measuring system consisting of sensors or transducers that continuously monitor the speed and position of the cutting tool. The control unit receives, recognizes and sends signals. It calculates the difference between the received feedback signal and the original, and then generates a signal that must correct the speed and position.

Remote Control

The console includes a display necessary to visualize operator commands, as well as other machine data. Its location can be customized according to the wishes of the operator.

Principle of operation

The working process is:

• Program selection using the control panel;
• Converting the processes embedded in the program into signals using the existing input mechanism that pre-reads it;
• Storing these signals during the entire metalworking process in the intermediate memory of the program and then erasing them;
• Transmission of a task for starting the operation of these signals using a special unit that controls all movements in accordance with the signals of a given program.

During operation, the machine performs not only basic but also additional functions. An example of an important function would be to feed drive control. A less significant example is the modification of the tool, as well as the modification of the rotation speed.

CNC makes it possible to work in automatic mode, as well as receive:

• Good quality;
• The required surface roughness;
• Programmed dimensional accuracy and conformity to product shapes.

CNC equipment helps not only to automate the entire production cycle, but also to make almost all production mechanisms semi-automatic or automatic. This makes it possible to create multi-station service, saving labor and increasing productivity.

Pros and cons of metalworking on CNC machines

Currently existing technologies make it possible to optimize production, increase the quality of products, and increase the power of CNC equipment.

It becomes more technologically advanced, new advantages of its use appear:

• Increased processing speed. The operator is only needed to start the machine, there is no need for manual reconfiguration. The machine changes cutting tools by itself. Accordingly, several actions are combined. Everything is done in one cycle, which significantly affects productivity growth.
• The production speed of the same type of products is the same. In the past, speed was influenced by various factors, including employee experience. CNC equipment spends the same amount of time on metal processing of the same parts, which is convenient when planning mass production.
• Precision metalworking. A correctly written program makes it possible to obtain identical products for a long time. The accuracy is so high that it does not exceed a micron. Human influence on the metalworking process is completely excluded.
• The ability to manufacture complex parts. CNC machines are excellent at handling details of almost any complexity. Therefore, this equipment is used in high-precision aircraft production and in the automotive industry. An example is the manufacture of products with mirror symmetry. This is an incredibly difficult task for handcrafting, but not for CNC machines.
• Staff reduction. Maintenance of automated equipment requires a small number of professional workers. The workshop requires 2–4 people, as their speed is high – they can service several machines in 12–15 minutes.
• The ability to build an automatic conveyor. If you combine several CNC machines that carry out metalworking into a production line, you can achieve complete automation of production.

At present, such complex personnel training is no longer required to work with the equipment. Despite this, the entire production process depends on the training of the operator of CNC machines, including how the equipment will behave, what will be the results of its work.