Four levels of checking
| Level | What it shows | What it can miss |
|---|---|---|
| Backplot | Tool centre path as lines | Gouges, stock, holders, machine |
| Material removal (stock) simulation | Stock being cut; gouges and leftover material | Machine limits and collisions with machine parts |
| CAM machine simulation | Machine model moving from CAM toolpath data | Errors introduced by the post processor |
| G-code machine simulation | Machine model driven by the actual posted NC code | Only what the model or controller emulation doesn't represent |
The key difference: toolpath vs G-code
CAM-based simulation checks what CAM intended. G-code-based simulation checks what the machine will actually do, including every decision the post made: rotary solutions, retracts, cycles and offsets. For new posts and 5-axis work, G-code simulation is the only way to verify the post itself.
Common tools
- VERICUT (CGTech): G-code simulation, verification and optimisation.
- NCSIMUL (Hexagon): G-code machine simulation.
- CAMplete: 5-axis verification and post-processing workflows.
- NX ISV with CSE: G-code-driven simulation inside NX.
- Fusion machine simulation, Mastercam and SolidCAM simulation modules.
What makes simulation trustworthy
[ ] Accurate machine model and kinematics
[ ] Correct controller emulation (cycles, TCP, offsets)
[ ] Real stock, fixtures and clamps
[ ] Real tool assemblies: holders, extensions, stick-out
[ ] Same work offsets and tool lengths as the machineWhen to use what
Backplot and stock simulation for every program; CAM machine simulation for multi-axis and tight setups; G-code simulation for new posts, 5-axis, mill-turn and high-value parts.
Simulation is only as good as the model behind it. Garbage in, crash out.
Simulation-ready post development
See our CNC post processor development service and verification before running code.