Free personalized metal finishing help!
Haziness or Cloudiness on Type III Anodized Titanium Med Screws
(-----) October 11, 2021
First time posting here. We ran into an some defects on a batch of screws during the anodization process. The defect can be described as intermittent areas of matte cloudy finish throughout the length of the screws. In other words, the finish along the body of the screw would be ok then cloudy then ok then cloudy again.
We're cleaning with high alkaline cleaner, #2 ringing with cold RO/DI water, #3 rinsing with hot RO/DI water, #4 acid etching, #5 rinsing with cold RO/DI water, #6 Acid neutralizing with high alkaline cleaner, #7 rinsing with cold RO/DI water, #8 Anodizing with Trisodium phosphate and RO/DI water, #9 and finally rinsing with cold RO/DI water.
I have posted the photos for a better visual of the issue. Any idea as to what may have caused this? I appreciate the feedback.
- Philadelphia, Pennsylvania
October 15, 2021
A. Hi Leo,
My opinion that there is local overheating. Make sure the temperature of the electrolyte is not higher than 70 °F, use large tank for mass anodizing, mask all non-essential surface of the basket or holder (assuming you use titanium baskets), do oxide etching of the basket regularly in-between loads, install moving rack or do electrolyte agitation by any possible means - cooling pump, magnet or mechanical means (in order to prevent local overheating).
October 22, 2021
I would try to slow down the ramping or reduce the amps because if you go too fast to a color you can get a lot more gassing which would affect the surface finish that could cause cloudiness on the parts. The cloudiness seems to be about the same location on different parts, so I would try racking them differently to see if it improves or goes away.
October 23, 2021
Mark is absolutely correct. Forgot to mention this issue. I assumed that low amp setting is on default when titanium color anodizing. But instead of guessing amps numbers we setup voltage raise for at least 30 seconds duration until it reaches the required color number, thus limiting amps by itself.