FANUC 3D interference checking: CNC built-in versus PC-based implementations and model validation
The FANUC function catalog distinguishes built-in CNC checking from a PC/FOCAS2 implementation. The article identifies validation priorities for geometry, tool data and communications, including the impact of fixture changes.
Contents
If 3D interference checking produces a false alarm or misses a fixture, first identify the implementation and the geometric objects it actually checks. A three-dimensional display alone does not establish complete coverage.
Technical differences between the implementations
Pages 107 and 109 of the FANUC Function Catalog (2024) describe built-in CNC 3D interference checking and the PC-related function respectively. The PC function's ordering table lists the 30i-B, 31i-B5, 31i-B and 32i-B. Available versions and supporting software must match the machine configuration.
| Implementation | Basic method described by the manufacturer | Project validation priorities |
|---|---|---|
| Built into the CNC | Real-time spatial checks inside the CNC using geometry and tool data | Correct geometric objects, coordinate relationships and current tool |
| PC-related function | A PC-side CAD system checks interference during actual machine motion through the FOCAS2 interface | Validate data synchronization, communication faults and machine response as well as the model |
The last column presents this article's proposed validation priorities; it does not mean the official product has already completed these checks for every machine.
Simplified geometry must cover the actual shape
The catalog describes built-in checking that represents relevant regions with geometric elements such as planes, rectangular solids and cylinders. A model's value lies not in visual appearance but in covering the actual shapes that could interfere.
For example, modeling a clamp with a raised section as only a low base can leave that raised section outside the checked geometry. Conversely, an oversized model that includes space intended to remain clear can generate unnecessary interference alerts. In either case, return to dimensions and coordinate relationships; do not simply enlarge or shrink a boundary to clear an alarm.
Assessing toolholder or fixture changes
The same tool-tip position does not mean the entire tool assembly has the same shape. After fitting a thicker holder or changing projection length, check the tool model against the actual installation. Changing clamps, jaws or tailstock position requires corresponding geometry and reference updates. Revalidation may be needed even if the program is unchanged.
Use approved offline or dedicated validation methods to check known close-approach regions, and establish whether mode changes, manual operation and abnormal states are within the acceptance scope. Do not test protection by causing actual parts to collide.
State the coverage with the conclusion
Handover should identify modeled objects, validated operating modes, handling of PC or communication faults, and responsibility for updates after changes. Results of 3D interference checking cannot replace an assessment of personnel safety. This site also does not treat promotional success-rate claims in a catalog as a guarantee against collisions. Other functions are covered in the OPTION section.