Rebarba

Rebarba, commonly translated as burr in English, is a rough edge or protruding fragment that remains on a manufactured part after a cutting, punching, drilling, milling, or forming operation. The burr may appear on external edges or inside holes and channels and results from plastic deformation or localized fracture of the material during separation from the workpiece. The size and shape of a burr depend on material properties, tool geometry, and cutting conditions.

Burrs form when the cutting action displaces material rather than cleanly removing it. Factors such as material hardness, tool sharpness, cutting speed, clearance, and part geometry influence burr formation. Burrs can be external, internal, or both, and may be straight, curled, or feathered along the edge.

The presence of burrs has practical consequences. They can pose injury risks to handlers, interfere with assembly or mating of parts, and affect dimensional tolerances, seals, or threads. Burrs can also act as initiation sites for corrosion or fatigue failure if left untreated. Therefore, deburring or edge finishing is a common post-processing step in many manufacturing workflows.

Deburring methods vary by part geometry, material, and production volume. Mechanical approaches include filing, grinding, sanding, brushing, shot blasting, and tumbling. Non-mechanical options include thermal deburring, which burns away burrs; electrochemical deburring, which dissolves excess material electrochemically; and chemical deburring, which uses etchants. Ultrasonic and robotic deburring can combine vibrations with tooling for complex geometries.

In practice, drawings and specifications often define acceptable burr limits to ensure safe handling and proper function. The term rebarba is used in some Iberian-language contexts; in English, burr is the common equivalent.