Custom Masking Parts for Anodizing: A Case Study
Are custom molded parts more expensive in the long run? Perhaps not - consider this case.
In 2012, a prominent Illinois anodizer contacted Viadon about some aluminum parts they were having difficulty masking adequately. At the time, this company was using a liquid masking for anodizing. While it usually got the job done, the liquid mask didn’t always work – rejects of parts were occurring, and not a small quantity.
One reason for this was the liquid mask itself; it needed to be applied several times on each part, on both sides. Because of this, the edge of the masked area was uneven. On top of all this, the cost for labor required to mask these parts was enormous; it often took two full days to apply liquid mask to these parts, not to mention the stripping required after anodizing.
Most problematically, the liquid mask was failing. This would be less of an issue if the entire part was aluminum, but the area to be masked was a steel insert going through the inside diameter. Because Type II anodizing was being used, sulfuric acid was a part of the process. And when sulfuric acid touches steel? Well… the steel “burns” away – or more accurately, it quickly corrodes the steel leaving a hole with no steel there.
Obviously this was an unacceptable result for the anodizer’s customer.