Stylus Profilometry
Is stylus profilometry a 2D or 3D method?
The basic instrument measures a 2D line profile; stitched scans can be assembled into a larger 3D surface profile in some systems.
What parameters does it commonly report?
Ra, Rq, Rz, step height, waviness, and form, depending on the filtering and evaluation method used.
When is it preferred over optical profilometry?
Contact stylus profilometry is preferred when a shop needs high-accuracy contact data, especially on standard industrial metal components, deep grooves, or surfaces where optical reflectivity is problematic.
Stylus profilometry is a contact surface-metrology method that uses a low-force, sharp stylus tip to trace a surface line and record height versus position. The resulting profile is used to calculate Ra, Rq, Rz, step height, waviness, and form. As a contact method, it provides traceable, standards-based roughness evaluation on cleaned, stable surfaces.
On the shop floor, stylus profilometry earns its place whenever a drawing calls for traceable, profile-based roughness data on relatively flat machined areas. The operator clamps or stages a clean, dry part away from vibration, selects the right stylus, and orients the traverse across the machining lay unless the print specifies otherwise. Software then applies the chosen cutoff and filter settings to separate roughness from waviness and form, producing Ra, Rz, or step-height values that can be compared directly to the specification. In practice, the method is used on finished metal faces, ground features, coated surfaces, and precision wood or composite finishes. Multiple measurements at different locations are often averaged to reduce local variation. Contact profilometry is preferred over optical areal mapping when the feature is a relatively flat line profile and the shop needs standards-based, high-resolution height data with a clear audit trail.
Dirty or Burr-Laden Surfaces: Cutting fluid, chips, dust, or edge burrs create false peaks and valleys, inflating roughness values and making a good part look out of tolerance.
Wrong Cutoff or Filter Setup: A mismatched cutoff wavelength or filter level can mix roughness with waviness or form, yielding numbers that do not represent the actual functional finish and causing bad decisions.
Contact Force on Soft Finishes: The stylus can scratch or deform soft coatings, plastics, and delicate millwork finishes, while the resulting distortion also corrupts the reading itself.