What is M Code – Know your CNC Machine Programming Language

A miscellaneous code, often abbreviated as M code is a programming language tasked with governing the stationary assignments of your CNC machine. They are typically exploited in tandem with G codes and this integration leaves your machine with an excellent automation level.

History of M Code

Halfway through the 20th century, a tremendous upsurge in automated manufacturing machinery was recorded. This consequently heightened the demand for programming languages to facilitate the swift operation of these automated machines.

Thankfully, John T. Parsons and Frank L. Stulen came up with the M code around this time.

To achieve this insane feat, they were aided by the Massachusetts Institute of Technology. The experiments that led up to the invention of the M code were hugely funded by the US Air Force. Thanks to these pioneering engineers, you can enjoy the automated and precise machining of distinct manufacturing machinery.

Why You Need M Code

If you own an automated manufacturing machine such as a CNC lathe machine, you must understand the essence of programming languages like M codes. Miscellaneous codes play a pivotal role in ensuring that your CNC machine undertakes its set roles with utmost automation and precision. This code will help you:

· Complement the G Code

The G code controls various essential functions of your CNC machine. Its coverage is however limited hence the need for a complementary programming language like M code. Integrating these two elaborate languages rewards you with a comprehensive language that allows you to govern virtually all functionalities of your CNC machine. For instance, fusing these two codes will allow you to regulate your machine’s movement and non-movement functions.

· Maximize Your CNC Machine’s Performance

Automation inevitably improves the efficiency and performance levels of distinct machinery. M codes facilitate the automation of essential functions in CNC manufacturing machines like milling systems. For instance, you can use an M code to initiate automatic machining tool changes. This will minimize time wastage consequently elevating your production volume and rate.

· Broaden Your Machine’s Application Spectrum

Thanks to M codes, you can accomplish several manufacturing processes with ease and great success. These codes can relay varying instructions to your CNC machine thereby prompting the implementation of distinct tasks. For instance, you can instruct your system to activate the cooling system using the M08 or halt the spindle rotation using the M05 code.

Structure of M Code

Virtually all machining operations dependent on Computer Numerical Control (CNC) owe their success to M codes. These codes act as languages that allow you to communicate with your CNC machine. They are generally standard codes but you might notice slight variations in machines manufactured by distinct manufacturers.

The typical M code demonstrates a relatively simple structure, which comprises a letter and numerical value. The designated letter for M codes is ‘M’, which is an abbreviation for miscellaneous. When broken down, the M code is as follows:

• M Designator: Miscellaneous codes always feature the letter ‘M’ at the start. This letter serves as the code’s identifier. This designator informs your CNC machine of the auxiliary task it is about to execute.
• Numerical Code: The designated letter is generally accompanied by a number and this number is responsible for articulating the specific function your machine should undertake. These codes typically range from 00 to 99.
• Additional Parameters: Certain M codes contain additional elements, which typically come after the numerical value. These values are separated by a space and they are tasked with expounding or specifying the provided instructions.

An example of an M code with an additional element is MO6 T1. When broken down, the M stands for stands for the miscellaneous function. 06 stands for the specific function, which is tool change while T1 specifies the cutting tool to be changed.

You must be wary that M codes are case sensitive hence you should avoid inputting these codes in lower caps. For instance, if you key in m06 instead of M06, you will get an error message.

Types of M Codes

CNC manufacturing machines or systems are typically tasked with a myriad of distinct functionalities. To allow them to successfully undertake these functionalities, varying types of programming codes are necessitated. When commanding CNC machining using M codes, you can exploit the following options:

• M00: This code allows you to halt the operations of your CNC machine momentarily. Once the machine stops temporarily, you can proceed to inspect certain components or even substitute a cutting tool manually. After making the necessary adjustments, you can proceed to re-activate the machine again.
• M01: This code is quite similar to the M00 in that it commands your CNC machine to halt operations temporarily. This code, however, only works when you have activated the optional stop setting. If this setting is off, your machine will bypass this instruction and keep on running.
• M02: This code instructs your CNC machine to end a specific iteration. It asks your machine to halt a CNC program once a specified machining process has been successfully completed.
• M03: This miscellaneous code instructs your CNC machine, particularly your machine’s spindle to start revolving and the rotating direction to assume. It instructs your spindle to revolve in a clockwise manner thus facilitating the execution of certain machining operations like milling and drilling.
• M04: Similar to the M03, this code also instructs your CNC machine’s spindle to activate and rotate in a specified direction. M04 commands your spindle to rotate in an anticlockwise manner and at a specified rotational speed. This paves the way for varying cutting operations including turning and threading.
• M05: This code halts the rotation of your machine’s spindle to allow cutting tool change. It instructs your spindle to halt movement or rotation. In addition to facilitating cutting tool substitution, this code also allows you to transition seamlessly between distinct machining operations.
• M06: Contemporary CNC machines come endowed with a myriad of distinct machining tools. M06 allows you to switch between varying machining tools manually or automatically. This code instructs your machine to retrieve the mounted cutter and substitute it with a designated cutter.
• M08: The M08 code instructs your CNC machine to set in motion the coolant system. This leads to the opening of a valve that lets a cooling fluid flow to your workpiece and machining tool. This fluid also helps with lubrication.
• M09: This code is also responsible for regulating the thermal conditions of your machining operation. However, M09 turns off the coolant system consequently cutting off the supply of a cooling fluid. These codes are essential in maintaining conducive thermal conditions that minimize tool wear.
• M30: This code bears a striking resemblance to M02. However, you must pay special attention to avoid confusing it with the M02 code. M30 signifies the conclusion of your machine’s entire program. After this command, your CNC machine is likely to initiate a shutdown procedure.
• M07: This miscellaneous code works on CNC machines equipped with mist coolant systems. It instructs this coolant system to get going allowing this cooling mixture to cool your workpiece and machining tool. This mist also serves as a lubricant consequently minimizing friction.
• M10: This code sends instructions to machining centers with pallet changers. M10 instructs your machine to unclamp the pallet allowing you to load or unload your workpiece from the pallet.
• M11: Just like the M10, this controls the functioning of pallet-equipped CNC machines. But unlike the M10, M11 is responsible for clamping the pallet allowing you to secure your workpiece in preparation for machining. This prevents unprecedented movement of your workpiece during machining.
• M19: M19 is a miscellaneous code that commands your CNC machining center to position your spindle in a predetermined angular position. This angular positioning, allows you to exploit your machine to accomplish sophisticated cutting operations like internal threading.
• M40: This code commands your machine to suspend its preset tool-changing routine. This allows you to manually intervene and change the routine. Simply put, M40 overrides your machine’s tool-changing sequence. This override gives you a window of opportunity to also inspect certain components.
• M98: This code allows you to call a specific subprogram, which is a block of codes tasked with executing machining operations like threading. These subprograms are typically located within the primary program.
• M99: Just like the M98, this code also regulates the functioning of specific subprograms. However, the M99 code does the opposite. It commands your CNC machine center to end the subprogram and revert to the main program. This is after the subprogram has successfully executed its set function.

How M Code Functions

M codes are like invisible conductors responsible for the successful execution of distinct machining operations undertaken by your CNC machine center. Understanding the nuances involved can help you optimize the operations of your machine. Beneath, we unravel the nuances involved when writing and reading M codes.

· Step 1: Programming

First, a main program is generated and installed in your CNC machine center’s control system. This CNC program is uniquely formatted and structured and it includes both G codes and M codes. It is these M codes that ultimately influence your machine’s non-movement functions consequently impacting its overall functionality.

· Step 2: Interpretation

CNC machines come with computer-controlled control boards, which break down the received M code once received. Your CNC controller reads your M code meticulously and this allows it to unravel the instructions relayed by the code. For instance, if it receives the following M code, M03, it will establish that the code wants the spindle rotated in a clockwise direction.

· Step 3: Implementation

After successfully interpreting the sent M code, your CNC control system is now in a position to execute the corresponding task. For example, if the control system reads the M Code as M03, it will activate the spindle and let it rotate at a specified speed. If the received M code is M06, the machine will automatically change the cutting tool.

CNC Machines Reliant on M Code

Computer Numerical Control has taken automation a notch higher hence its immense adoption across multiple manufacturing machinery. CNC not only elevates your machine’s accuracy but also broadens its application spectrum. Here is a list of CNC machinery utilizing M codes behind the scenes to ensure smooth operation.

· CNC Lathe Machines

Lathe machines have dominated the manufacturing world for ages and with the inclusion of computerization, their prominence has gone a notch higher. CNC lathe machines allow you to machine your workpieces with great precision consequently rewarding you with consistently high-quality components. M codes allow you to control specific actions in lathe machines including spindle movement and tool changing.

· CNC Milling Machines

Milling machines permit you to perform numerous actions on your workpieces including turning, facing, and drilling. M codes play a pivotal role in ensuring that your milling machine accomplishes these tasks with great success. You can exploit M codes to activate and deactivate your coolant system or even increase or decrease spindle rotation speed.

· Grinding Machines

Grinding machines help you craft components with smooth surface finishes. M codes come in handy in grinding machines since they allow you to control essential tasks like wheel dressing and tool change. This elevates your grinding machine’s precision consequently rewarding you with consistently high-quality products.

·  CNC Laser Cutting Machines

These machining systems deliver consistently high-quality components since they utilize laser cutting. M codes permit these machines to accomplish their set tasks with optimal precision and success by governing their functioning. For instance, you can utilize an M code to instruct your laser cutting machine to focus the cutting tool on a specific area or activate gas assist.

· Electric Discharge Machines

These machining units are renowned and revered for the manner in which they extract unwanted materials from your workpiece. They exploit electrical discharge and this gives them an edge over conventional machining centers. By incorporating M codes, electric discharge machines fine-tune essential functions including flushing and actuation.

Benefits of M Code

It is no secret that M codes have made far-reaching changes in the operation of CNC machining centers. These codes allow you to govern your machine’s key functionalities and this comes with a plethora of rewards. These rewards include;

• Simple: Whether you are a programmer or a CNC machine operator, you will find writing and reading M codes quite easy. These codes are easy to interpret and this permits your CNC machining center to execute the dictated commands with great precision.
• Streamlined Operations: M codes help you eliminate dependence on manual labor since they automate most of your CNC machine center’s operations. These codes allow you to streamline your machining operations thereby facilitating repeatability.
• Readable: Deciphering an M code is quite easy since it only involves two elements. A letter ‘M’, which is an identifier and a numerical value, which specifies your respective command.
• Enhanced Precision: Certain M codes control the positioning and rotation speed of your spindle and cutting tool. This eliminates room for error consequently rewarding you with well-machined components.
• Real-time Processing: Thanks to M codes, you can adjust machining operations without necessarily having to shut down your CNC machining center. M codes are received and interpreted by your machine instantly.
• Flexible: You can exploit varying types of M codes to prompt the execution of distinct machining operations. For instance, you can utilize M03 to activate clockwise spindle rotation or M06 to automatically substitute cutting tools.
• Reduced Workload: Thanks to M codes, all you need to do is monitor the operations of your CNC machine. M codes initiate essential functions consequently eliminating the need for human intervention.
• Improved Control: M codes automatically relay instructions to your CNC machine thus provoking the execution of certain tasks. This allows you to control the precision in which your machine undertakes the specified task.

M Code Simulators

Miscellaneous code simulators allow you to pilot study M codes prior to relaying them on your CNC machine. Thankfully, you can exploit various M code simulators including;

• CNC Simulator Pro
• Mach3
• Mastercam Simulator
• CAMotics
• NCSim
• NC Viewer
• G-Wizard Editor

M Code Vs G Code

G codes and M codes are often mistaken to be the same programming language for CNC machines. They are however distinct codes, which work in harmony to execute and streamline automated machining operations. The underlying table illustrates the key differences between these essential codes.

Features	M code	G Codes
Function	Govern non-movement machining operations.	Govern the movement of machine components.
Main Application	Regulate auxiliary functions.	Control cutting tool movement.
Standardization	They are generally standardized.	Although they are standardized, they come in varying forms.
Example	Clockwise or anticlockwise spindle rotation.	Linear or circular interpolation.
Coolant Control	Activates and deactivates coolant systems.	Does not control the operations of coolant systems.
Tool Positioning	Does not regulate the positioning of your cutting tool.	Regulates the positioning of your cutting tool.

Applications of M Code

M codes play a pivotal role in governing the non-movement operations of your CNC machine center. This has made them indispensable resources when it comes to automatic machining centers. You can exploit them to accomplish the following tasks:

• Program stop
• Optional stop
• End programs
• Clockwise spindle rotation
• Anticlockwise spindle rotation
• Spindle stop
• Coolant system activation
• Clamp on and off
• Feed hold
• Subprogram call

Are you having problems configuring your CNC machines? Well TSINFA engineers are here to provide a permanent solution to all your problems.

More Resources:

CNC Lathe Machine – Source: TSINFA

M-Code and CNC Programming – Source: THOMASNET

CNC M-codes – Source: IQS DIRECTORY

G-code for CNC – Source: WIKIPEDIA