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Anodizing problem on AA 5052 Alloy

Q. I AM WORKING WITH HITACHI-ABB POWER-GRIDS INDIA. WE ARE OBSERVING DARK LINE OBSERVED, AT DIFFERENT LOCATION OF SECTION & IN LONGITUDINAL DIRECTION, ON ANODIZED ALUMINUM EXTRUSION. ANODIZED THICKNESS IS 15 - 20 MICRONS. WHAT COULD BE REASON FOR THIS LINES!

61335-1 61335-1dtl

SHAH HEMANT
- VADODARA, GUJARAT, India
September 24, 2021

A. Hi Shah. Maybe I'm misunderstanding, but I don't see how you can extrude a shape like that, and I'm not seeing anything to give me a sense of scale.

That short black line could be etching, but are you sure it's not mechanical damage -- a scratch?

Luck & Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
October 2021

Q. Sir, we are using extruded rectangle section of 255 mm width & 20 mm thickness, 400 mm length. This section machined from both side of section & its thickness reduced to 18 mm. After machining this section is anodized in sulfuric acid bath to obtain 15 micron thickness. After anodizing line marks observed at different location in longitudinal direction as shown in photograph.

SHAH HEMANT [returning]
- VADODARA, GUJARAT, India
October 7, 2021

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