Burrs

Burrs are a term used for two distinct kinds of phenomena that share a rough or adhesive quality: plant seed structures that cling to fur or fabric, and protrusions or rough edges left on a material after a cutting or shaping operation.

In botany, burrs (seed burrs) are fruits equipped with hooks, spines, or sticky surfaces that attach to animals, humans, or clothing. This attachment facilitates seed dispersal, a strategy known as epizoochory. Common examples include burdock (Arctium spp.), beggar-ticks (Bidens spp.), and stickseed (Hackelia spp.). The hooked or bristly structures can persist in the environment long enough to transport seeds to new locations. While useful for plant dispersal, burrs can be a nuisance to people and livestock and may contribute to the spread of invasive species.

In manufacturing and machining, a burr is a raised or rough edge left on a workpiece after cutting, drilling, punching, grinding, or casting. Burrs can be sharp and may create fit problems, trap moisture, cause corrosion, or lead to injury. They can form internally or externally and vary in size and shape depending on the process and material.

Deburring is the common set of techniques used to remove or reduce burrs. Methods include manual filing or grinding, deburring blades, chamfering or counter-sinking edges, tumbling or vibratory finishing, abrasive blasting, and, in some cases, chemical or thermal treatments. Effective burr management is important for product quality, safety, and longevity.