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"Picture frames get "flow lines" after anodizing"


My name is Lee HC from an anodizing services company in Malaysia.

I work as an QA Executive in the company and recently we face problem
of flow line in our picture frame profile after anodizing.

The process flow as below :
Degreasing - Rinsing - Brightening - Rinsing - Anodizing - Rinsing - Rinsing - Rinsing
- Dying - rinsing - hot seal - rinsing - Drying.

Al raw material series used is 6063.

Anybody can advise me on the removal of flow line from the picture frame visible surface after brightening or anodizing process?


Lee Hwa Chang
Nanyang Strategies Sdn Bhd - Selangor, Malaysia


It would help to know at what exact stage of the process that you see the flow line. I suspect that you may be leaving the hot dye on too long before rinsing and/or sealing as I have seen this happen first hand.
Perhaps you could detail your process better.

Michael Null
Plater - Methuen, Ma, U.S.A.


Thanks Mr Micheal,

Below is the exact parameter control:

Degreasing at temp 40 ~ 50 °C abt 10 mins time
Rinsing at abt 40 C
Brightening at 80 °C 2 mins
Anodizing at 21 C 30 mins
Dying is 20 mins
Hot seal is 70 ~ 75 C at 2 mins

Perhaps this would provide sufficient info to you.


Lee HC
- Selangor, Malaysia.


Dear Mr Michael,

Thank you for you reply.

My process parameter as below :
Degreasing - 40 - 50 C, 10 mins
Brightening - 80 °C , 2 mins
Anodizing 22 C, 35 mins,10V
Dying - 30 mins
Hot seal - 2 mins

Hope the above will provide sufficient info for you.


Lee HC
- Selangor, Malaysia.

April 6, 2010

I don't see a deox step listed after the brite-dip. It would also help to know if you are performing any rinsing of the parts/racks as the load comes out of the brite-dip bath. Both the b-dip itself clinging to the parts, and the fumes coming off the parts (while the b-dip is clinging to the load) can leave flow marks on an aluminum surface. If the fumes are attacking the aluminum, the orientation of the streaks will be toward the ceiling (based on the parts racking), and if b-dip is dripping from the parts, the streaks (or flow marks) will be in a downward direction toward the floor.
The best way to prevent this would be to continuously rinse the bar/racks/parts as they are being raised out of the b-dip bath. Continue rinsing (if possible) as you move the load over into the deox bath.

Jim Ploski
Automatic Anodizing
Chicago, Illinois
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