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TIME REQUIRED FOR HARD ANODIZING



(-----) 2006

Q. DEAR SIR,

WE ARE MANUFACTURING HARD ANODISING COOKWARE. THE AVERAGE TIME FOR PROCESSING IS 90 MINUTES. WHEN WE RECEIVE SOME MATERIAL THE TIME GOES UP TO MORE THAN 120 140 MINUTES FOR THE SAME LEVEL OF HARD ANODISING. MY QUESTION IS :
1. DOES THE METAL CONDUCTIVITY CHANGE THE TIME REQUIRED FOR PROCESSING?
2. DOES THE TEMPER OF METAL CHANGE THE TIME REQUIRED FOR PROCESSING?
3. WHAT IS THE BEST TEMPER AND CONDUCTIVITY LEVEL TO GET THE BEST AND FASTEST RESULTS ?

THANKS & REGARDS,

MOHAN BHOGALE
COOKWARE - INDIA
^


First of two simultaneous responses -- 2006

A. Anodizing time is controlled by current density going through the part. Temperature and concentration differences would be reflected on the ending voltage difference applied provided the current density be the same.
Additionally, Temperature and concentration will surely affect the results of HCl bubble test, Voltage Break-down, hardness, etc.
However, different material has different thickness build-up speed at the same current density. 5052 is faster than 7075, while 7075 is faster than 6061.

John Hu
- Singapore
^


Second of two simultaneous responses -- 2006

A. Mohan

1] Yes

2] Yes

3] Alloy and temper choice will depend upon your manufacturing and application requirements. Best choice will be performance oriented, and fastest choice will be economically oriented.

Willie Alexander
- Colorado Springs Colorado
^



Hardcoat anodizing is taking longer than it used to

April 16, 2014

Q. Hi, I have been hardcoat anodizing for 30 years. Lately I am having a problem with how long it takes to get the required thickness. It used to take about 90 minutes to get a 2.5 mil thickness, now it's taking approx. 180 minutes to get the same thickness. My system is capable of 70 volts and 70 amps and is self regulating. When I preset the current to the load I have and start to bring the volts up they stop at 8.7 volts with the current up to working current. It takes approx. 20 minutes for the volts to rise and another 20 minutes to reach starting volts of 24. My tank is 60 gallon with a 10% sulphuric and 28 °F. This is the first time I have came across this problem. My titrations are 180 g/l sulphuric acid and 2 g/l aluminum content. I am not sure of the iron content because I am not sure how to check it. If anyone has any idea on what is going on, please let me know.

Thanks,George

George Uhl
- Franklin, Pennsylvania U.S.A.
^


April 2014

A. Hi George. Although there could be a number of explanations, my first guess is that the rectifier is having a problem like single phasing. If it's practical to measure the input current with an Amprobe you may be able to detect this. Or if you have access to a ripple meter or an oscilloscope you can see such a problem. Or depending on the rectifier design you may be able to spot a defective diode.

Regards,

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