Bead Blasting: Media Types & Surface Finish
The default prep pass before most finishes — it removes tool marks and gives the coating something to grip.
Request a quoteWhat actually happens to the part
A high-velocity stream of media is directed at the surface. The media cuts or peens the surface depending on its hardness, which either removes a layer or work-hardens the surface.
| Parameter | Value |
|---|---|
| Glass bead (non-reactive) | Light duty, cosmetic, no contamination risk |
| Aluminium oxide | Standard prep for paint and anodise |
| Stainless steel shot | Peening, adds compressive stress |
| Common grit | Ra 1.6–3.2 µm uniform matte |
| Masking | Threads, bores and datum faces |
| Surface roughness | Ra 1.6–3.2 µm, uniform matte |
| Typical lead time added | Add 1–2 working days |
What this finish does to your tolerances
This is where most prototype surprises come from. A finish is not decoration — it moves dimensions, and the drawing has to account for it.
Light blasting removes a few micrometres and rounds every sharp edge. On a cosmetic part this matters — a 0.05 mm chamfer will be visibly rounded. We increase the edge break before blasting on cosmetic work.
Suitable for
- Almost every metal
- Aluminium, steel, brass, copper
- Blast before anodising or powder coating
Not suitable for
- Precision mating surfaces and datum faces — blasting will move them
- Very fine tolerances on a thin wall — the part flexes during blasting
- Soft plastics — media will embed and mar the surface
What engineers ask about Bead Blasting: Media Types & Surface Finish
Do I need blasting before anodising?
Almost always, yes. Anodising grows from the surface, and any tool mark or contamination under the layer shows up magnified in the finished part. Blasting gives a uniform substrate.
Why did my edges look rounded after finishing?
Blasting and coating both work on edges. On a cosmetic part we specify a larger chamfer or radius up front so the finished edge matches the intent.