Different from last week’s post, in this test, the customer wanted a uniform, matte surface finish. In order to provide some comparison, two parts were blasted to show the surface finish differences. These parts were blasted with similar sized blasting media at the same pressure.
In the part at the top of the picture, you can see the blasting result is a satin-matte surface finish. While nothing like a near-mirror finish, the part does reflect some light. Upon very close-up inspection, you would be able to see very light peening on the surface – sort of like rolling hills. This finish was achieved by blasting with the Glass Beads – 100/170 Medium-Fine grade.
The part on the bottom is more of a flat-matte finish and does not show any indication of reflectivity. On a micro scale, this part is etched rather peened and looks like sharp peaks and valleys. This finish was achieved by blasting with Aluminum Oxide Grit – 120 Mesh.