What is CNC?

CNC stands for computer numerical control, which is a technology that uses a microcomputer installed on a tool to automatically control processing tools. The CNC machine will run according to coded programming instructions, such as the movement of the machine, the feed rate of the material, the speed, etc. There is no need for an operator to manually control the machine, so CNC helps to improve efficiency and accuracy to a large extent.

From the development of the first CNC machine tool in the 1940s to 2022, CNC technology has been continuously developing and has played a vital role in different industries. In this blog, we will introduce this technology in more detail, including the working principle of CNC, the different processes of CNC machining, and its advantages.Let's continue reading.

How does CNC work?

In a CNC system, a microcomputer is used to perform all basic functions according to a program loaded in the machine control unit, which can send commands to the servo drive to achieve various functions, such as turning on and off the motor and coolant, replacing tools and pallets. In addition, all CNC operations are continuously monitored by feedback equipment (such as proximity sensors, pressure sensors, etc.). Therefore, if any errors occur, the system will generate a “fault message” to alert the operator.

Types of CNC machine tools

CNC milling machine

Usually, CNC milling machines are composed of a three-axis system, namely X, Y and Z axes. Some advanced milling machines can accommodate three additional axes. This kind of machine can run programs composed of number and letter prompts, which can guide the workpiece across different distances. As for programming, G code and other unique languages developed by the manufacturing team can be used for milling machines.

lathe

CNC lathes can perform high-precision and high-speed cutting, and lathes use indexable tools to cut workpieces in the circular direction. The lathe has similar functions to a CNC milling machine and can also be controlled by G code and other unique codes, but the lathe has only 2 axes (X axis and Z axis). CNC lathes are suitable for manufacturing complex products that cannot be achieved by hand.

Plasma cutting machine

CNC plasma cutting machine is mainly used for cutting metal materials, and in a few cases it can also be used for cutting other surfaces. During the cutting process, compressed air and electric arc combine to produce plasma, which can provide sufficient speed and heat to cut metal.

CNC electric discharge machine

Electric discharge machining (EDM) is a process that uses electric discharge to shape a workpiece into a specific shape.

During the processing process, a continuous discharge is generated between the two electrodes, which can remove unwanted materials from the workpiece. In EDM, the material is placed between the two electrodes, and then the machine calculates the amount of discharge that each electrode needs to generate.

CNC laser cutting machine

Its working principle is similar to that of a CNC plasma cutting machine, the only difference is that the laser cutting machine can be used to cut various materials such as metal, plastic or hardwood. The intensity of the laser can be adjusted according to the different densities and intensities of the materials used.

CNC router

CNC router is a very practical machine, it uses a computer to control the cutting machine, can be applied to a variety of materials, such as steel, wood, aluminum, plastic and so on. Compared with other machines, it has higher productivity and reduces waste by manufacturing different items in a short time.

CNC machining

A variety of materials can be used for CNC machining, including plastics, metals, wood, glass, etc., which makes it a very popular technology in a wide range of industries such as automobiles, medical care, electronics, and telecommunications.

CNC machining steps

Step 1: CAD model design

In the first step, we need to design a 2D or 3D CAD model. This is usually done by using computer-aided design software. Information such as the size and geometry of the product will be included in the CAD file.

Step 2: File conversion

In the second step, we need to convert the CAD file to a CNC-compatible file format, usually “G code”, so that the CNC machine can recognize it. Here, we will use computer-aided manufacturing (CAM) software to run such files, which will generate digital programming code to control these machines.

Step 3: Machine setup

Before the machine starts working, we need to set it up. For example, we need to test speed and positioning to ensure good performance.We need to install the required tools on the appropriate machine parts. This is a very important step, because incorrect settings can also damage the machine and parts.

Step 4: Processing operation execution

In the last step, the CNC machine tool will start working according to the instructions issued by the program. Every action of the machine tool and the tool will be carried out in strict accordance with the program, so the final product processed by the CNC will be exactly the same as the original design.

Common processes of CNC machining

CNC milling

In the CNC milling process, rotating multi-point cutting tools are used to remove excess material and make parts with specific shapes. The whole process is controlled by a computer to ensure the high precision of the parts. The process can also be used for rapid prototyping and finished parts.

The milling process is not complicated: first, we need to design a CAD model that can be either 2D or 3D. Secondly, convert the CAD file to a “G code” so that the CNC machine can recognize it. Finally, set up the CNC milling machine and start working.

CNC turning

CNC turning is usually carried out on a CNC lathe or turning center, and unwanted materials are removed by combining the rotational movement of the workpiece with the translational movement of the tool. CNC turning is a very cost-effective technology with a high material removal rate and can be used to cut wood, metal and plastic. The mechanical design of CNC lathes is simpler than that of CNC milling machines, and the cost is lower when producing the same parts.

Advantages of CNC

High production efficiency

CNC machines can automatically perform a series of actions, all we need to do is program and set up the machine. Only a few steps are involved, and more importantly, as long as the machines are not faulty, these machines can work 24/7 without interruption. Therefore, it can greatly improve production efficiency.

Consistency and accuracy

Compared with manual processing, CNC machine tools are controlled by computers, which helps to eliminate manual errors and improve the accuracy and consistency of different batches of products. Therefore, CNC is very suitable for projects that require high product quality and reliability.

Cost-effective

Although the initial cost of CNC machines is high, their high productivity and low manufacturing error rate make them an affordable choice for many manufacturers. Think about it, if there is any human error that leads to rework or repair, what will be the cost? In addition, less manpower is required in this process, and skilled operators can operate multiple machines at the same time. CNC technology is becoming more and more popular, which also helps to reduce the cost of these machines.

Suitable for various parts

CNC is versatile and can be applied to different parts. On the one hand, it can manufacture parts of different shapes from simple to complex with high precision. On the other hand, we can reprogram the CNC machine to manufacture brand new parts in a short time.