Molded Parts 5 and 6

  • Molded parts for anodizing masking

Custom Molded Parts for Anodizing Masking: 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 well. At the time, this anodizer was using a liquid, UV-cured paint-on maskant. While it usually got the job done, the liquid mask didn’t always work – rejects of parts were occurring.

One reason for this was the liquid mask itself; it needed to be applied several times. Because of this, the edge of the masked area was uneven. On top of all this, the 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, sometimes the liquid mask failed. 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.

Viadon Designs a Perfect Custom Mask

Enter Viadon. We designed two, custom-molded masks for these parts. The two sides of the part were different; one was flat, and the other had a raised, circular ridge. So Viadon color-coded the two masks so masking operators could quickly identify the parts to go on each side.

A yellow masking plug was designed that had slightly angled edge underneath.

yellow anodizing plug
Yellow Masking Plug

A blue masking plug was designed that accounted for the raised circular ridge.

blue anodizing plug
Blue Masking Plug

(Note: the pictures with the blue and yellow plugs show the old, poor result part with the plug over it. See photo below for the clean lines created by these plugs.)

Each masking plug employed a tapered outer edge, so that a large washer would be able to distribute pressure to the surfaces that contacted the aluminum, completely masking the steel insert. This was achieved via a ¼” bolt that was placed through a hole in both of the plugs.

The Final Results of a Perfect Custom Mask

With a simple wingnut tightened down on this assembly, the resulting masking lines were perfectly round.

Clean anodizing masking lines from custom plugs
Clean anodizing masking lines from custom plugs

There were no uneven edges. Reject parts dropped from 10% - 15% down to zero. And most importantly, the anodizer saved a lot of money, as the time required to mask them went from 2 days to 30 minutes!

Another satisfied Viadon customer! Viadon delivered a solution saving our client time and money and increasing their customer satisfaction.

To find out more about custom masking parts for your next metal finishing project, Contact the professionals at Viadon.

Viadon. A Cut Above.