Bead Blasting
Propelling fine glass beads at the surface under pressure to create a uniform matte texture. Removes tool marks and machining lines without altering dimensions.
About Bead Blasting
Bead blasting is a surface finishing process that propels fine spherical glass beads at high velocity against a workpiece surface using compressed air. The impact of millions of tiny beads creates a uniform, non-directional matte texture that effectively conceals CNC tool marks, minor scratches, and surface irregularities. Unlike angular abrasive media (such as aluminum oxide grit), glass beads are spherical and do not remove significant material, preserving the dimensional accuracy of machined parts.
Bead blasting is one of the most popular finishing operations for CNC machined parts because it produces a clean, professional appearance at low cost and fast turnaround. It is commonly used as a standalone finish for internal components or as a preparatory step before anodizing, powder coating, or other coatings. The uniform matte texture improves paint and coating adhesion and creates an aesthetically consistent surface across multiple parts in a production batch.
The process is versatile and can be applied to virtually any metal or hard plastic. By varying the bead size (#80 coarse to #220 fine), air pressure (30-80 psi), and nozzle distance, operators can control the resulting surface roughness from a pronounced matte finish to a subtle satin texture. Bead blasting is non-toxic, generates no chemical waste, and the glass media can be recycled multiple times before replacement, making it an environmentally responsible finishing method.
Finish Properties
How It Works
In bead blasting, parts are placed inside an enclosed blast cabinet equipped with a compressed air nozzle. The operator directs a stream of fine glass beads (typically soda-lime glass, 40-200 µm diameter) at the workpiece surface at pressures ranging from 30-80 psi. The spherical beads strike the surface and create tiny overlapping dimples that collectively produce a uniform matte texture. The operator systematically covers all exposed surfaces, adjusting angle and distance to ensure consistent coverage. The process is typically performed manually for complex geometries or in automated tumble-blast systems for high-volume production. After blasting, parts are cleaned with compressed air to remove residual media and debris.
Design Guidelines for Bead Blasting
Mask critical sealing surfaces, precision bores, and threaded features before bead blasting to prevent texture from affecting fit or seal integrity.
Specify bead size in your finish requirements—#120 is the standard for a balanced matte finish; use #80 for aggressive texture removal or #220 for a finer satin finish.
Apply bead blasting before anodizing or coating rather than after, as it improves adhesion and creates a more uniform coating appearance.
Be aware that bead blasting will round sharp edges slightly (approximately 0.05-0.1 mm)—account for this on features where sharp edges are functionally required.
For consistent results across multiple parts, specify air pressure and distance parameters in addition to bead size to ensure batch-to-batch repeatability.
Compatible Materials
Materials that can be finished with bead blasting.
Bead Blasting FAQ
Bead blasting has negligible dimensional impact. Glass beads are spherical and relatively soft compared to the metal substrate, so they deform the surface plastically at a micro level without removing measurable material. Typical dimensional change is less than 0.01 mm, which is well within standard CNC machining tolerances. However, repeated or aggressive blasting on soft metals like pure copper may produce slightly more surface displacement.
Bead blasting uses spherical glass beads that produce a smooth, uniform matte finish without material removal. Sandblasting uses angular abrasive media (aluminum oxide, silicon carbide, or steel grit) that aggressively cuts into the surface, producing a rougher texture and removing material. Bead blasting is preferred for cosmetic finishing of precision parts, while sandblasting is used for heavy cleaning, rust removal, and creating aggressive surface profiles for coating adhesion.
Yes, bead blasting can be applied to hard engineering plastics such as ABS, polycarbonate, nylon, and PEEK at reduced pressures (15-30 psi). Softer plastics may deform or develop an uneven texture. Glass beads are the preferred media for plastics as they are less aggressive than angular abrasives. Always test on a sample part first, as results vary significantly between plastic types.
Bead blasting can serve as a final finish for parts where a matte appearance is desired and corrosion resistance is adequate for the application. However, bead-blasted surfaces on bare aluminum or steel are more susceptible to fingerprints and oxidation than coated surfaces. For parts exposed to moisture, chemicals, or handling, following bead blasting with a clear anodize, passivation, or clear coat is recommended to maintain the appearance and provide lasting protection.
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