Kerf is the width of material removed by the cutting stream. In abrasive waterjet cutting, the mixing tube influences that width. The kerf needs to be considered when the programmed path is placed relative to the finished contour.
A nozzle dimension is a starting point
The mixing-tube diameter is relevant to the cut, but the finished kerf should be measured. As a mixing tube wears, its bore and the resulting cutting width can change. Treat the current nozzle condition as part of the setup record, rather than relying indefinitely on the value used when it was new.
The jewel orifice and mixing tube perform different tasks: the orifice forms the water stream, while the mixing tube guides the abrasive stream toward the workpiece. Their dimensions should not be used interchangeably when discussing cutting width.
Width and taper are separate checks
The width at the top of a cut can differ from the width at the bottom. This is taper. Feed rate and the behavior of the jet through the material affect the cut face; a correct contour offset does not by itself establish that the wall is perpendicular.
For a mating part, decide where the dimension matters and inspect that surface. For a through-thickness fit, inspect the cut face as well as the top outline.
Put compensation on the scrap side
Tool compensation accounts for the cutting width when the head follows the drawing. For an outside profile, the path must preserve the part boundary; for an internal opening, it must preserve the opening. Check the direction and side of the offset in the controller's preview before running the job.
Use the controller's definition of tool offset. Record whether its input expects a cutting width or an offset distance; do not transfer a value between different definitions without checking it.
Verify the setting with the part
Cut a test feature in the intended material and thickness using the proposed settings. Measure an external feature and an internal opening, and check taper where it affects the fit. Record the nozzle condition, working pressure, abrasive setup and feed rate with the measurements.
When a dimension drifts, review the measured kerf and nozzle condition alongside the program. Changing the drawing to conceal an unexplained offset error makes the next setup harder to reproduce.
See cutting speed and cutting thickness, or request a quote for the proposed configuration.