G-code is the most widely used computer numerical control programming language. It is primarily used in computer-aided manufacturing to control automated machine tools and has many variants. G-code instructions are given to the machine controller (industrial computer), which tells the motor where to move, how fast to move, and what path to follow. The two most common cases are that in machine tools such as lathes or mills, the cutting tool is moved according to these instructions, cutting away material through the toolpath, leaving only the finished part and/or the unfinished part precisely positioned around three Any of up to nine axes in three dimensions, relative to the toolpath, and one or both of which can move relative to each other. The same concept extends to non-cutting tools such as forming or polishing tools, additive methods such as photo-drawing, 3D printing, and measuring instruments. All CNC machines rely on G-code to function.
G-code programming is used in conjunction with M-code. M code stands for machine code and controls various functions of CNC machine tools that are not directly related to motion. These functions include commands such as machine loading programs, program pauses and coolant flow.
The Application of G Code in NC Machining
G code is the most widely used CNC programming language, mainly used in computer-aided manufacturing to control automatic machine tools.
G-code plays a vital role in CNC programming. CNC machines cannot understand conversational language. They use a dedicated set of machine language commands. Programmers compile these commands into G-code files that instruct the CNC machine how to operate. G code is an instruction in the NC program, generally called G instruction, using G code can realize fast positioning, reverse circular interpolation, forward circular interpolation, intermediate point circular interpolation, radius programming, and jump processing.
Are all G-codes common in CNC machine tools?
There are more than one hundred G-code commands for CNC programming. Most G-codes are common to every CNC programming operation. However, certain G-codes are specific to types of operations such as milling, turning, drilling, etc. G-code listings may vary between different CNC manufacturers. Not every machine supports all G-codes. Additionally, machines with unique features or multi-axis machining capabilities may have additional G-codes. The manufacturer may provide instructions for G-code for CNC programming in the reference yearbook accompanying the machine tool. The G-code may vary slightly depending on the specific build model you are using, before referring to your machine’s owner’s manual, check your equipment’s CNC programming design for differences.
Knowing G-codes is essential for learning CNC programming and making any part by automating the machining process, there are many different G-codes for different instructions. You can refer to the table below for G-codes to use when working on a CNC programming project.
|Commonly used G code types in CNC machine tools|
|G-code that controls motion and toolpaths in CNC programming|
|G00||Machine tool moves quickly|
|G01||Machine tool linear interpolation|
|G02||Clockwise circular arc interpolation|
|G03||Counterclockwise circular arc interpolation|
|Plane selection G-code program specifies a two-dimensional plane in the X, Y, Z axis Cartesian coordinate system|
|G17||XY plane selection|
|G18||XZ plane selection|
|G19||YZ plane selection|
|G-code programs for dimensions indicate which units of measure are selected|
|G20||Change unit measurement to inches|
|G21||Change unit measurement to mm|
|Tool compensation codes take into account parameters such as tool length and tool radius. Using these commands increases the precision of the entire CNC operation.|
|G40||Cancel tool length compensation|
|G41||Cutter Compensation Left|
|G42||Cutter Compensation Right|
|G43||Tool Length Compensation|
|Workpiece offset, zero offset ensures that the workpiece is in the true zero position|
|G54||Work Offset 1|
|G55||Work Offset 2|
|G56||Work Offset 3|
|G57||Work Offset 4|
|G58||Work Offset 5|
|G59||Work Offset 6|
|Canned cycle G-code program|
|G73||High-speed deep hole drilling canned cycle. Chip breaking while drilling|
|G74||Peck drilling canned cycle, usually used for face grooving. For tapping only.|
|G75||Quick grooving cycle for CNC lathe|
|G76||Fine Boring Canned Cycle and Threading Cycle|
|G81||Standard Drilling Canned Cycle|
|G82||standard drill with dwell at the bottom of the hole|
|G83||Deep hole peck drilling cycle, retracts the entire hole|
|G84||Right-hand tapping cycle for threading into pre-drilled holes|
|G85||Reaming cycle or Boring cycle|
|G86||Bore and stop canned cycle; the spindle stops when the tool reaches the bottom of the hole|
|G87||Boring cycle for enlarging the hole diameter with special tools|
|G88||boring cycle with P command; P indicates the number of seconds to stay|
|G89||Back boring cycle with dwell|
|cancel code||speed and feed|
|G50||zoom out||G94||Feed per minute mode|
|G80||Cancels all active canned cycles||G95||Feed mode per revolution|
|G96||constant surface speed|
|G97||constant spindle speed|
|G90||Use absolute mode for positioning||G98||return to initial plane|
|G91||Use incremental positioning||G99||return fast plane|
|G10||Program Offset Input||G51||Zoom|
|G22||Store travel limit||G52||Temporarily move the program to zero|
|G23||Store stroke limit cancel||G53||Return to Machine Zero|
|G27||Zero Check||G60||one-way movement|
|G28||Return to Zero||G61||Exact stop check (modal)|
|G29||return from reference position||G64||normal cutting mode|
|G30||Second position return to zero||G65||Custom macro call|
|G31||Jump function||G66||Custom macro modal call|
|G44||Negative Tool Length Compensation||G67||Cancel custom macro modal call|
|G45||Single offset increase||G68||coordinate rotation mode|
|G46||Single Offset Reduction||G69||cancel coordinate rotation mode|
|G47||Double Offset Increase||G92||Program Work Offset|
|G48||Double Offset Reduction|
Precautions for writing G codes for CNC machine tools
CNC machine tools need to cut different materials, including many materials with high hardness. Therefore, writing errors in G-code may cause safety hazards to machines, operators and work areas. It is a relatively common accident that props are damaged due to collisions. Therefore, factors such as workpiece offset and tool length offset should be considered when writing G codes to ensure that tool damage does not occur.
When writing G code, you need to keep the following points in mind at all times:
- Be familiar with the functions of the CNC system (such as the g command of the fanuc system);
- Understand the structural characteristics and performance indicators of machine tools;
- Master the setting method of processing route and process parameters;
- Familiar with the types and specifications of the knives used, and choose the knives reasonably
- Familiar with the use of commonly used measuring tools.
- Use various measuring tools correctly.
- Correct use of fixtures.
- Pay attention to safe and civilized production, and always remember safety first.