# What G-Code and M-Code Mean in CNC Machining

Computer Numerical Control machines process materials to meet the specifications of programmed instructions. CNC machines include lathes, grinders, machining centers, and many other tools.

The machinery has become very popular in the manufacturing industry because it can be used with a wide variety of materials and provide much greater accuracy and consistency than other tools.

Furthermore, CNC machines can operate without the need for an individual operator to control the equipment. But a CNC machine still needs to be programmed by a human being before it can begin producing parts. That is where G-Code and M-Code come in.

## An Overview of G-Code

If you are interested in becoming a programmer, there are now a number of different industries that you can work in, including the manufacturing sector. As a CNC machine programmer, you would create a sequence of codes and data to form a program that tells the CNC machine precisely what to do.

With the right tooling, the program can then ensure the machine produces accurate and repeatable parts. It is a great idea to use a used CNC machine when job training because it is more affordable; especially when learning cases.

In order to create a CNC machine program, you need to learn G-Code. In basic terms, it is the software programming language that is used to control a CNC machine. Thankfully, G-Code is written in a logical and straightforward way, even with complex CNC machining.

The “G” is followed by a number. That number is a command that changes the geometry. For example, “G00” is a command for the machine to make a rapid movement to a specific coordinate position.

So, it basically enables the CNC tool and the part it is producing to move from near to far and vice versa. Other commands include “G01,” which controls the movement of the linear feed, and “G02” and “G03,” which perform the move in a clockwise or counterclockwise direction.

The code for such operations is also followed by a geometric location. So, the “G” and the proceeding numbers are followed by coordinates for the machine’s X and Y axes. For example, take the G-Code of “G00G58X-120.Y-5.”

You already know that the first three digits refer to a rapid movement. “G58” is the code that specifies the work coordinates that change the geometry relative to the work offsets, such as part origin. The numbers that follow “G58” in the example of “G00G58X-120.Y-5” therefore indicate the X-axis needs to be “-120mm” and the Y-axis needs to be “-5mm.”

The G-Code can repeat actions for as long as needed. With the right use of code and coordinates, CNC machines can consistently perform and be flexible enough to produce a variety of parts from a multitude of materials.

## An Overview of M-Code

M-Code in CNC machining basically organizes miscellaneous functions. Think of them as non-geometry machine functions. They include things like pallet change, the on and off of coolant, and the start and stop of spindle rotation.

The functions often vary depending on the precise CNC machine being used. Also, M-Code is more specific for different machinery and is more customizable than G-Code. Both M-Code and G-Code are vital for a CNC machine to perform correctly.

Like the format of G-Code, M-Code consists of the letter “M” followed by a number. For example, M00 instructs the program to stop whatever it is currently doing, while M03 is used to rotate a spindle clockwise, M08 is used to turn coolant on, and M09 is used to turn coolant off.

## Final Thoughts

Are you good at programming and interested in machining? If so, spend some time learning more about CNC machines, M-Code, and G-Code so you can determine whether it is the right career path for you.