FANUC Tilted Working Plane: what to check before 3+2 machining
Tilted Working Plane helps organize programs around inclined machining faces. Using a hypothetical angled-hole scenario, this article explains the relationships among TWP, machine orientation and workholding datums, and lists the information to check before 3+2 machining.
Contents
When a part has machining faces in several orientations, programmers often want to describe holes or contours in each face’s local directions. Tilted Working Plane (TWP) can help organize such programs, but the software coordinate definition and the machine’s actual orientation must still be checked together.
Applicability and function description
The official FANUC TWP description explains that the function supports programming around inclined surfaces and reduces manual geometric calculations. The 31i-B product information lists TWP among five-axis-related functions. This article discusses machines equipped with the relevant function. It does not imply identical configurations across all 31i-B, 0i or other series. Check the manual for the applicable software version for definition methods, soft keys and commands.
Start with the angled-face hole requirement
The following is a programming-analysis example. Suppose an inclined face of a workpiece has a regular hole pattern. First define the face’s origin, two in-plane directions and normal vector, then organize hole spacing and depth. This expresses the part’s geometric requirements. The machine definition and program sequence must determine the rotary positions selected and the approach to the workpiece.
In what is commonly called 3+2 machining, inspect rotary-axis positioning for the required orientation and the subsequent three-axis cutting as two stages. The ability to define a tilted plane does not by itself establish simultaneous five-axis machining capability. Nor does a change in displayed coordinates prove that the table has reached the required orientation.
A suggested information checklist
- Check that the machining-face orientation and datums in the drawing agree with the workpiece datum established after clamping.
- Record the rotary-axis arrangement, positive directions, effective travel and the machine builder’s rotary-axis positioning and locking conditions.
- Verify the tilted-plane definition used by the postprocessor, especially angles, directions and transformation order. Avoid mixing examples from other machine models.
- Check approach, withdrawal and indexing paths before and after positioning. A reachable cutting position does not prove that the intermediate indexing motion is collision-free.
- Archive the validated program, coordinate settings and fixture revision together for checks when the job is repeated.
Recognizing common misconceptions
“The same tilt angle should produce the same axis position” overlooks machine kinematics and possible orientation choices. “The program needs no check after changing the setup” overlooks datum changes. “TWP eliminates calibration or measurement” confuses program representation with actual geometric accuracy. Validate these assumptions against the machine’s conditions rather than merely comparing how similar the code looks.
Before trial machining, complete simulation, path review and controlled validation as required by the machine manufacturer. This article does not provide a universally executable indexing program. For tool center point control, see TCP configuration checks, or return to the OPTION section for more material.