Blasting (Topic: 14113)

Abrasive blasting with shot or grit is only used to a limited extent on aluminium to clean or apply a decorative finish to surfaces. Steel abrasives are not favoured, because of corrosion problems. Blasting is therefore best carried out with materials such as fused alumina and glass beads. The process is particularly suitable for producing a good basis for coating.

Attractive satin finishes can be obtained by vapour blasting in which a fine abrasive suspended in water is used to produce a satin finish. This can subsequently be given an anodic treatment. Combinations of blast treatment and polishing can give decorative and artistic finishes on architectural fittings such as shop fronts. Clear anodising is usually the post-treatment.

Abrasive blasting has an important value in producing mechanically advantageous effects on aluminium alloys which are subject to stress or fatigue. Shot peening work-hardens the metal surface, whilst the impact prevents the spread of cracks.