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ngr1
12-03-2004, 01:04 PM
Hello, I read somewhere that sand blasting can be used to alter the finished of aluminum as well as blend in minor imperfections and machining marks left by cutters (i.e. end mills).

In searching futher I have found material such as Glass Bead, Aluminum Oxide and Silicon Carbide can be used in the blasting process.

Does anyone have any info regarding this topic they could share?

Thanks... Norman

HuFlungDung
12-03-2004, 01:39 PM
Add dry ice to the list, too. It might be hard enough to blast aluminum with, and no mess!

buscht
12-03-2004, 02:06 PM
Our suppliers use small glass beads to even our surface texture on aluminum castings. Sand is sharp and actually cuts into the aluminum skin causing pitting.

I'm sure glass beads will work well on machined aluminum parts

kenlambert
12-03-2004, 05:11 PM
aluminum oxide works well to clean up imperfections glass leaves a smoother finish (nuts)

NeoMoses
12-04-2004, 04:14 PM
Glass bead will leave a nice matte finish. It is fairly easy to blend imperfections less than 0.005" or so. Taller discontinuities will take more time.

most types of true 'sand' are angular, and will leave a rougher finish. However, the rougher the material is, the quicker it will cut.

Mouldmaker
12-06-2004, 05:01 AM
We use glass bead to give Aluminium a "Satin" like finish. It also removes minor imperfections (cutter marks) from the surfaces.

ngr1
12-06-2004, 04:06 PM
Thanks Everyone!

sbrpollock
12-06-2004, 05:37 PM
I tend to stay away from anything but glass bead.

The "sand" type products that have sharp corners leave microscopic indentations with corresponding sharp corners in the bottoms of them. These (I've been taught) create what are called stress-risers that are the starting points of cracks and eventual failure.

Stress-risers are like the score you make in a piece of glass in order to cut it. It snaps right allong where the score is.

Glass Bead leaves indentations that are spherical in the bottom and does not introduce these stress-risers. In fact, many people I'm familiar with actually glass bead high stress pieces like conecting rods just to "relieve" surface stress and eliminate any stress-risers left by other processes.

Want a famous example? Though I never heard the results of any tests (this is pure speculation), the first thing I thought of when I saw that right front wheel break off of Kurt Busch's car (for no apparent reason) during the last race of the Nextel Cup Championship, was If it had been "Sand" blasted at one time.