AiVibeLinear and Circular Interpolation (G01, G02, G03)
Interpolation is how a CNC coordinates several axes so the tool follows a straight line (G01) or an arc (G02 clockwise, G03 anticlockwise) at the programmed feed rate, as opposed to rapid positioning with G00.
In linear interpolation the control moves all programmed axes simultaneously so the tool travels in a straight line to the end point at the commanded feed rate. In circular interpolation it moves two axes in the selected plane along an arc, defined by the end point plus either centre offsets (I, J, K) or a radius (R). G02 cuts clockwise and G03 anticlockwise, viewed from the positive end of the axis perpendicular to the plane chosen with G17, G18 or G19. Rapid positioning with G00 moves at maximum rate, and on many controls each axis moves independently, so the path is not necessarily straight.
Linear and circular interpolation produce most contours, pockets, faces and bores. Adding a linear move along the third axis to a circular move gives helical interpolation, used for thread milling and for helical ramping into material. Some controls also offer spline or NURBS interpolation for smooth freeform surfaces.
Freeform surfaces from CAM are usually approximated by many short linear segments, so tolerance settings and the control's look-ahead affect surface quality and achievable feed. Arc programming errors, such as an end point not lying on the circle, are rejected or interpreted differently depending on the control, which is another reason to verify programs before cutting.
Key points
- G01 moves in a straight line at feed rate; G00 positions at rapid rate
- G02 and G03 cut clockwise and anticlockwise arcs in the selected plane
- Arcs are defined by I, J, K centre offsets or an R radius
- Helical interpolation adds a linear axis to an arc for thread milling and ramping
Where AiVibe comes in
AiVibe designs and manufactures the AiAmbA AI Factory: edge devices plus AI agents that let people talk to CNC, PLC and robot controllers in plain language. Agents only propose changes, and a trained operator confirms each one.
Related terms
- G-codeCNC & Precision Machining
- CNC ControllerCNC & Precision Machining
- ToolpathCNC & Precision Machining
- Feed RateCNC & Precision Machining
- Cutter Radius Compensation (G41, G42)CNC & Precision Machining