beadformation

Bead formation is the process by which discrete beads are produced from a liquid or melted material as it solidifies or fragments, forming small spheres or near-spherical particles. It occurs in a variety of disciplines, including metalworking, polymer science, and colloid and interface science.

In welding and brazing, a weld bead is the deposit of molten filler metal along a joint. Its shape and dimensions depend on heat input, travel speed, electrode or nozzle geometry, shielding conditions, and base-metal wetting. Improper bead formation can lead to defects such as porosity, undercut, or lack of fusion.

In polymer science, beads are produced by droplet-based processes such as suspension or emulsion polymerization, where droplets of monomer or prepolymer are stabilized and polymerize or solidify into beads. Bead size distribution is governed by agitation, stabilizer concentration, interfacial tension, viscosity, and polymerization kinetics.

In microfluidics and emulsion technology, bead formation can be achieved by flow focusing or jet break-up, producing monodisperse droplets that can be solidified to form beads or used as carriers. Parameters include flow rates, channel geometry, interfacial tension, and phase viscosity.

Bead formation is assessed by size uniformity, sphericity, and surface quality; common metrics include average diameter and polydispersity index. Understanding bead formation helps optimize materials performance in coatings, composites, and biomedical assays.