What is CNC machining? Overview of CNC machining process

CNC machining is a manufacturing process in which pre programmed computer software instructs the movement of factory tools and machinery. This process can be used to control various complex machinery, from grinders and lathes to milling and router planers. By using CNC machining, 3D cutting tasks can be completed in a set of prompts.

The CNC machining process is an abbreviation for “computer numerical control”, which is opposite to the limitations of manual control and replaces the limitations of manual control. In manual control, on-site operators need to prompt and guide the commands of machining tools through joysticks, buttons, and wheels. For onlookers, a CNC system may resemble a set of conventional computer components, but the software programs and consoles used in CNC precision machining distinguish it from all other forms of computation

How does CNC machining work?

After activating the CNC system, the required cutting will be programmed into the software and assigned to the corresponding tools and machinery, which will perform the specified dimensional tasks like robots.

In CNC machining programming, code generators in digital systems typically assume that the mechanism is defect free, although there is a possibility of errors, which becomes even greater whenever the CNC machine is oriented to cut in multiple directions simultaneously. The placement of tools in a numerical control system is outlined by a series of inputs called part programs.

On CNC machine tools, programs are inputted through punch cards. In contrast, programs used for CNC machine tools are inputted into the computer through a small keyboard. CNC programming is retained in computer memory. The code itself is written and edited by programmers. Therefore, CNC systems provide greater computing power. The best thing is that CNC systems are never static, as new prompts can be added to pre-existing programs through modified code.

Numerical Control Machine Programming

In CNC precision machining, the machine operates through a numerical control system, in which a software program is specified to control the object. The language behind CNC machining, also known as G-code, is used to control various behaviors of the corresponding machine tool, such as speed, feed rate, and coordination.

Basically, CNC machining can pre program the speed and position of machine tool functions and run them in repetitive, predictable cycles through software, with almost no manual operation required. Due to its functions, this process has been adopted in various corners of the manufacturing industry, particularly in the fields of metal and plastic production.

For beginners, they will conceptualize 2D or 3D CAD drawings and then convert them into computer code for CNC systems to execute. After entering the program, the operator will conduct a trial run to ensure that there are no errors in the coding.

Open/Closed Loop CNC Machining System

Position control is determined through open-loop or closed-loop systems. Using the former, the signal runs in a single direction between the controller and the motor. In a closed-loop system, the controller can receive feedback and perform error correction. Therefore, closed-loop systems can correct irregularities in speed and position.

In CNC machining, motion is usually oriented along the X and Y axes. Conversely, by positioning and guiding the tool through stepper or servo motors, these motors will replicate the precise motion determined by the G-code. If the force and speed are minimized, the process can be operated through open-loop control. For all other aspects, closed-loop control is necessary to ensure the speed, consistency, and accuracy required for industrial applications such as metal products.

Fully automatic CNC machining

In today’s CNC protocols, the production of parts through pre programmed software is mostly automated. Use computer-aided design (CAD) software to place the dimensions of a given part in place, and then use computer-aided manufacturing (CAM) software to convert it into an actual finished product.

Any given workpiece may require various machine tools, such as drill bits and cutting tools. To meet these needs, many machines today combine several different functions into one unit. Alternatively, an installation program may consist of multiple machines and a set of robotic arms that transfer parts from one application to another, but all operations are controlled by the same program. Regardless of the settings, the CNC precision machining process allows for consistency in part production, which would be difficult to manually replicate if not impossible.

Different types of CNC machine tools

The earliest CNC machine tools can be traced back to the 1940s, when electric motors were first used to control the movement of existing tools. With the advancement of technology, mechanisms have been enhanced through the use of analog computers and ultimately digital computers, leading to the rise of CNC machining.

Nowadays, the vast majority of CNC armories are completely electronic. Some of the more common processes in CNC machining operations include ultrasonic welding, drilling, and laser cutting. The most commonly used machines in CNC systems include:

CNC milling machine

The CNC machine used for CNC machining can run on a program composed of prompts based on numbers and letters, which can guide workpieces at different distances. The programming for the grinder can be based on G-code or some unique languages developed by the manufacturing team. The basic milling cutter consists of a three-axis system (X, Y, and Z), although most newer milling cutters can accommodate three additional axes.