International Standard ISO EIA
Introduction
CNC programming is a crucial step in the process of creating and running CNC machines. It is the code that enables machines to produce precisely the parts and products that manufacturers need. International Standard ISO EIA, commonly called G and M code, is the widely used language of CNC programming.
ISO EIA stands for International Organization for Standardization, Electronic Industries Alliance. This is an international governing body responsible for setting and maintaining numerous international standards and codes. Although the ISO sets the standards, individual countries may implement their own variation of the ISO EIA standards. This is why different countries may use slightly different versions of G and M code for CNC programming.
G and M Codes
ISO EIA codes consist of two main components – G codes and M codes. G codes instruct the machine on which geometric functions to use, such as drilling, milling, tapping and turning. M codes guide the machine in the statistical process control (SPC) for setting and troubleshooting.
These commands are used to control tools, feedrates, machine speed, coolants and other machine functions. Because the G and M codes are universal, they are used in most CNC programming applications, regardless of the machine being used.
Program Structure
G and M code instructions inform the machine as to what operations should be done. These instructions must be structured properly so that the program will execute properly. Each program begins with a title block identifying the machine, the program, date of program creation and the other information specific to the machine. The initial comments provide additional information such as the toollist, the feedrates and any other setup information needed. The main body of the program contains G and M codes, which are organized in specific sequences for the particular job being done. A comment line is placed at the end of each operation to explain what is performed. Finally, the program is ended with a special M30 command.
Benefits
ISO EIA codes are used throughout the CNC machining industry because they are easy to learn and use. They follow a logical sequence, so even a novice programmer can create a program with little difficulty. Furthermore, these codes are not tied to a particular machine brand or type, making them highly versatile. Finally, G and M code can be used with different machines in different parts of the world, making it useful for global machining operations.
Conclusion
ISO EIA is a widely used and accepted language for CNC programming. Its use provides the benefit of uniformity, which allows CNC programmers to quickly create programs for virtually any type of CNC manufacturing. G and M codes provide a logical and consistent system for controlling CNC machines, allowing them to produce the precise parts and products that manufacturers need.
