Computers and Technology

What is CNC machining and how does it work?

What is CNC machining?

CNC machining

CNC stands for Computer Numerical Control, which means computer numerical control. It refers to controlling the amount of movement, rotation speed, etc. of tools such as drills and cutting tools numerically.

Old machine tools like lathes and milling machines have been used in the past are manually operated by workers.

Since lathes and milling machines, which require precision in units of 1/100 mm and 1/1000 mm, are in the area of ​​craftsmen there was a problem that even inexperienced people could not make satisfactory products.

However, in the case of a CNC machine tool equipped with a computer control device. If the movement amount of the work piece or tool is replaced with the coordinate values ​​of the X, Y, and Z directions. And the program is input, the machine will automatically perform the rest. Unlike conventional machining, where experience is important, CNC machine tools can be used with the same dimensional accuracy.

CNC machining is common at many manufacturing sites in order to cope with labor shortages and mass production. Computer-assisted manufacturing is a mechanism to generate machining details with CAM based on CAD shape data after designing parts with CAD.

Specifically, it generates a tool path and machining conditions that encode the movement path that the cutting tool follows.

How does CNC machining work?

A CNC machine consists of a computer, which input the corresponding program according to the needs of the work. You can do everything on computer like cutting and programming dimensions. So, that the computer knows specifically what to do and performs all the machining. A CNC machine works like a bot: as soon as a program runs, all commands are executed.

Commonly used CNC-operated machine tools, including but not limited to: lathes, milling machines, drilling machines, etc. The main motive of these machines is to cut parts of the metal into the proper shape. These machines are generally run by humans (by the specialists who operate these machines). And since most work pieces require precise cuts, the operators have considerable expertise required to complete accurate work pieces.

However, the CNC machining machine can minimize the role of the operator. The operator only requires to enter the instructions program in the computer. And load the required tools on the machining machine, after which the computer will automatically perform all other operations. The computer will guide the machine tool to perform numerous cutting operations according to the instructions.

Advantages and disadvantages of CNC machining

Leading machine tool consumers in 2020, with a breakdown by select country. In that year, China accounted for approximately 32 percent of the world’s machine tool consumption. As you can see its CNC machining has become vital for big economies like China. Let’s talk more about its advantages. When requesting CNC machining of parts from a contractor, you must understand the advantages as well as the disadvantages. Here, we will explain the basic advantages and disadvantages.

Advantages of CNC machining

The main merits are as follows.

Stable product quality

A CNC machine ensures stable product quality. In general general-purpose machine tools, machining must be done manually, such as by operating the handle. Machining a high-precision product in the order of one-hundredth of a millimeter requires a certain level of skill .And manual work can cause differences in finish due to operational mistakes and workers.

High processing efficiency

Since CNC machine tools are automatically machined, one of the merits is that they can be used for mass production. With lathes and milling machines, tools such as cutting tools and end mills must be replaced manually, but CNC machine tools also automatically replace tools.

Therefore, one worker can manage multiple machines at the same time, which can contribute to solving the shortage of personnel and reducing costs.

High safety

A machine tool is a mechanism that rotates tools and work pieces to perform machining. Therefore, in general-purpose machine tools, there was an occupational accident in which a worker was caught in a rotating part during machining and suffered an accident. However, CNC machine tools are automatically machined inside a rugged cover, reducing the risk of an accident.

Disadvantages of CNC machining

The disadvantages are as follows.

High initial cost

Machine tools equipped with CNC generally tend to be more expensive than general-purpose machine tools. Moreover, since software such as CAD and CAM and peripheral devices must be installed.

Requires program expertise

Since CNC machine is performed by a program called NC code, specialized knowledge of the program is compulsory. If you can’t imagine the finished image from the floor plan, programming from scratch may cause processing mistakes.

Also, even if there is a mistake in the numerical value or the compatibility. The machine will not let you process according to the input contents and will not make adjustments during processing like human beings. Therefore, it is necessary to check the program regularly and review the dimensional accuracy.

Types and characteristics of CNC machining

Various machining can be performed by numerically controlled CNC machining. The main processing methods include drilling, milling, and lathe processing. Here, we will explain each feature.


Drilling is the process of drilling holes by applying a rotated tool to the work piece. Machines for drilling are not only old drilling machines, but also milling machines and machining centers that use NC cords.

The types of drilling include holes for bearings, screw holes etc. And the types of tools used for each are different.

The most commonly used method of drilling is to make a hole through the work piece. Remaining is used for finishing the hole. And the inner diameter and dimensional accuracy of the hole are adjusted to smooth the hole of the drill.

CNC milling machine and its features

Milling involves cutting a work piece fixed to a table by rotating a cutting tool like milling cutter or end mill attached to a rotating shaft. The fixed work piece is moved in the X and Y axis directions .And the rotated tool is moved in the Z axis direction to control the cutting amount on three axes. Tools used include front milling cutters and side mills.

CNC lathe machine and its features

Lathe machining is suitable for machining cylindrical products. You can rotate the centered work piece and apply a fixed tool called a bite to scrape the outer circumference, taper it, and perform centering and parting off.

There are mainly general-purpose lathes and NC lathes in lathes. And general-purpose lathes adjust the cutting amount by operating the handle in the same way as general-purpose milling machines. Nowadays, computer-based CNC lathes have become the mainstream, and CNC lathes are also called NC lathes at manufacturing sites.

CNC laser machine and its features

The CNC cutting machine has the characteristics of fast cutting speed and small cutting seam in the cutting process. The design of the industrial master machine ensures the high speed and stability of the laser cutting process. Optional fiber lasers with different powers can perform high-speed precision machining of cutting and punching of various metals and materials. The cutting quality is always maintained. Laser machines are used in sheet metal processing, environmental protection equipment, chassis electrical cabinets etc.

What do CNC machinists do?

CNC machinists work with CNC heavy machinery to produce parts and tools from metal or other materials. Computer numeric controlled machining is a precision machinery that cuts, grinds, or drills into the material.

How Much Do CNC Machinists Make?

In the USA, the Bureau of Labor Statistics (BLS) reports the May 2021 median annual salary for computer numerically controlled tool operators is $42,260 per year. This means half of CNC machinists made more and half earned less. Be aware that salary depends on several factors, including experience, employer, demand and cost of living in the area.

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