Marking a cylinder means choosing between a rotary axis and a 3D scanner
A flat scan field over a curved surface goes out of focus. Two established answers exist, and they suit different part mixes.
A standard marking system focuses to a plane. Present it with a cylindrical surface and the centre of the mark is in focus while the edges are not, because the surface curves away from the focal plane. Beyond a modest arc, the mark degrades visibly.
Rotary axis
Mount the part on a rotary stage, mark a narrow band at the top where the surface is effectively flat, index the part, mark the next band. The system stitches bands into a continuous mark around the circumference.
This suits cylindrical parts of consistent diameter — tubes, shafts, rings, medical instruments. It is mechanically simple and produces good quality because every band is marked near focus.
The costs are cycle time, since indexing takes time, and stitching quality: band boundaries can show if synchronisation between rotation and marking is imperfect. Continuous rotation with synchronised marking avoids visible seams but demands tighter control.
3D scanning
A three-axis scanner adds a movable focusing element ahead of the deflection mirrors, so focal distance can be changed dynamically. The system marks the curved surface directly by adjusting focus as the beam moves across it.
This handles arbitrary surfaces, not just cylinders, and it avoids mechanical part motion entirely. Cycle time is lower because there is no indexing.
The requirements are a 3D model of the surface, accurate part positioning relative to the model, and calibration of the focusing axis. Positional error translates directly into focus error, so fixturing accuracy matters more than in flat marking.
Choosing
Consistent cylindrical parts in volume generally favour rotary: simpler, cheaper, well understood. Varied geometry, conical or complex surfaces, or parts that cannot be rotated favour 3D scanning.
Mixed production often ends up with both, which is a legitimate outcome rather than a failure to standardise. The error worth avoiding is buying a flat marking system for curved work and discovering the focus limit after installation.
This article was produced by the LasersNews AI desk and reviewed by our editors.
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