An Introduction to Process Planning and G-Code CNC Machining An Introduction to Process Planning and G-Code

Process Planning Determines appropriate procedures for transforming raw materials into a final product given an engineering design Engineering designs convey information such as dimensions, tolerances and material CNC machining is used to transform engineering design to product

Machine Instruction When the designed product is produced using CNC machine tools, the machine tool controller needs explicit instructions describing the type and order of individual steps required to perform a given task. We use an instruction language called G-Code to deliver these instructions to the machine.

Advantages Does what manual machines can’t do Repeatability Reduce time and warehousing costs Reduced lead time and tooling costs Lower operator skill requirements

Disadvantages Requires large investment Machines do not program themselves Must invest in software and computers High maintenance costs Not cost effective at low production levels

G-Code An alphanumeric code delivering instructions to CNC machine Revolution Mill uses a standard Cartesian coordinate system for tool paths Code is evaluated one line segment at a time called a block

Common G-Code G00 Rapid linear motion G01 Linear motion at preset feedrate G02 Circular feed motion – CW G03 Circular feed motion – CCW G04 Dwell can be timed or untimed G40 Deactivates cutter compensation G80 Deactivates canned cycles

Common M-Code M00 Program stop M03 Spindle on (CW) M04 Spindle on (CCW) M05 Spindle off M07/9 Turn coolant (mist) on/off M06 Change tool M30 End program

Other Codes S Spindle speed F Feed rate T Tool number X,Y,Z coordinate axis motion R arc / corner radius I X-axis center offset J Y-axis center offset