The two trade associations, the Metal Finishing Association of Northern California (MFANC) and the Metal Finishing Association of Southern California (MFASC) are announcing their 2010 Supplier Showcase taken Tuesday and Thursday, February 16 and February 18.
February 16, 2010
SUPPLIER SHOWCASE
Quiet Cannon
Montebello, CA
4:00 PM - 8:00 PM
February 18, 2010
VENDOR SHOWCASE
Nepredak Hall
San Jose , CA
The Surface Finishing Academy will host the second anodizing workshop at the Embassy Suites - Silicon Valley coinciding with the annual MFANC Supplier Showcase Night in San Jose. The MFANC event will immediately follow our workshops on February 18th.
All SFA students will receive complementary general admission to the Supplier Showcase, and MFANC members may receive a 10% tuition discount for either of our San Jose courses. Please contact Paul Fisher at the Surface Finishing Academy if you have any questions or need more information.
If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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Metal Finishing trade associations work together with SFA and AluConsult to increase the knowledge in the finishing industry
Chromic Acid Anodizing
As told in an earlier post regarding different anodizing electrolytes, the Chromic Acid Anodizing, CAA, was the first commercial anodizing process patented in 1923 by Bengough and Stuart.
Chromic acid anodizing is mostly used for protection of critical structures with all kinds of joints. The corrosion resistance is excellent relative to the thickness of the coating, which normally lies in the range of 0.08 – 0.2 mil. The oxide film is softer and less porous than those formed by the other processes, and is formed without any significant fatigue loss of the material. The film is easily damaged and the color is light opaque gray. When this film is sealed in a dichromate seal a greenish color appear.
The process is voltage controlled with a ramping in the beginning of the process increasing up to 40V depending on the type specified. Two types are specified in the military specification MIL-A-8625F, Type I and Type IB, whereas the first is conventional coatings produced by a voltage of around 40volts and Type IB uses a voltage of 20 to 22 volts.
Other specifications are AMS 2470 and ASTM B 580 for Chromic Acid Anodizing.
The anodizing process steps for Chromic Acid Anodizing are usually more simple than the ones for the Type II anodizing (SAA = sulfuric acid anodizing). The work should be cleaned by vapour degreasing and if necessary an additionl alkaline cleaning. After a final rinse in clean water the work should be ready for anodizing.
Different customers call out different process parameters which sometimes makes it difficult to handle a variety of customers.
Some of the various customer specifications are:
Chromic acid anodizing is mostly used for protection of critical structures with all kinds of joints. The corrosion resistance is excellent relative to the thickness of the coating, which normally lies in the range of 0.08 – 0.2 mil. The oxide film is softer and less porous than those formed by the other processes, and is formed without any significant fatigue loss of the material. The film is easily damaged and the color is light opaque gray. When this film is sealed in a dichromate seal a greenish color appear.
The process is voltage controlled with a ramping in the beginning of the process increasing up to 40V depending on the type specified. Two types are specified in the military specification MIL-A-8625F, Type I and Type IB, whereas the first is conventional coatings produced by a voltage of around 40volts and Type IB uses a voltage of 20 to 22 volts.
Other specifications are AMS 2470 and ASTM B 580 for Chromic Acid Anodizing.
The anodizing process steps for Chromic Acid Anodizing are usually more simple than the ones for the Type II anodizing (SAA = sulfuric acid anodizing). The work should be cleaned by vapour degreasing and if necessary an additionl alkaline cleaning. After a final rinse in clean water the work should be ready for anodizing.
Different customers call out different process parameters which sometimes makes it difficult to handle a variety of customers.
Some of the various customer specifications are:
- Boeing BAC 5019
- Cessna CSFS020
- Eclipse EAC1006A
- Bombardier MPS160-10
The main use of Chromic Acid Anodizing is due to the fact that residues from the chromic acid trapped in parts that are difficult to rinse does not lead to corrosion. Another important feature is the fact that Type I coatings keep the aluminum materials fatigue strength and the very thin layer makes a minimal dimensional change.
Alloys are not allowed to contain more than 5% copper or 7% silicon, and total alloying element must not exceed 7.5% according to MIL-A-8625F. The alloys should be in one of the following temper before anodizing, T4, T6 or T73.
The electrolyte should consist of 50 - 100 g/L chromic acid and with a temperature of 95 - 105F. The purity of the chromic acid should not be less than 99.5% CrO3. Chloride is the worst contamination for the electrolyte and shouldn´t exceed more than 20 g/L. Chloride present in the electrolyte causes etching of the aluminum.
The hexavalent chromium content, the free chromic acid, decreases during the process and the trivalent chromium and aluminum increase.
Most of the Chromic Acid Anodizing is processed at 40 V, the low voltage is only used for special alloys which are difficult to handle at the higher voltage, as e.g. 2014 and 7075. Ramping is essential is this type of anodizing.
An easy way to remember the ramping time is the following;
For the all the alloys using 40 V, use 40 minutes to increase the voltage to 40V and then anodize for another 30 minutes. For the alloys using 20V, the same pattern can be used, use 20 minutes to get to the 20V and then spend another 30 minutes at that voltage.
The two different voltages used for Type I and Type IB create a slighty difference in the oxide film formed which can be seen in SEM images below of the surfaces.
Type IB, 22Volt
Type I, 40 V
The specifications for the performance of the coatings are a little different than for hard anodizing but the same procedures should be used. The difference is the weight of the formed coating which should be min 200 mg/ft2 and the coating should pass 336 hour in a salt spray test for Type I coatings.
It has to be mentioned that hexavalent (CrVI) compounds, often called hexavalent chromium, exist in several forms. Hexavalent chromium is recognized as a human carcinogen via inhalation. For more information check out, United States Department of Labor or The European Union directive, Directive 2002/95/EC.
If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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Aerospace article in Metal Finishing
Check out the new issue of Metal Finishing for the article "Overview of Anodizing in the Aerospace Industry".
If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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Anodizing in different acid solutions
The Chromic Acid Anodizing, CAA, was the first commercial anodizing process patented in 1923 by Bengough and Stuart, followed closely by the first Sulfuric Acid Anodizing (SAA) process patented in 1927.
The oxalic acid was introduced by the Japanese in the middle of the 1950´s. The main interest today is as an additional acid in Hard Coat Anodizing (HCA) to produce a harder coating faster than obtained with a pure sulfuric acid electrolyte.
Phosphoric Acid Anodizing (PAA) and Boric Sulfuric Acid Anodizing (BSAA) are both developed by the Boing Company, the first one as a structural bonding surface and the other as a replacement for the Chromic Acid Anodizing for non-critical fatigue parts.
If you find this article useful and you would like to know more please contact me blog@aluconsult.com__________________________________________________
Anodizing Workshop all over US
I'm excited to annouce my new LinkedIn account and would like to invite my readers to link up with me over there. You can find me here http://www.linkedin.com/in/annedeaconjuhl
Speaking of LinkedIn, I have also created an event for the first Anodizing workshop that we have scheduled for 2010 - you can find out more here http://events.linkedin.com/Introduction-Anodizing-Workshop/pub/197688
We'll be taking this course on the road, and will cover most of the country - so chances are that we'll be to a town near you soon, and I hope to see you there.
Also don't forget to check out my article on the front cover of the Finishign Talk newletter. Click here to get a free copy of the issue Finishing Talks 1 Newsletter in 2010.
If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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Speaking of LinkedIn, I have also created an event for the first Anodizing workshop that we have scheduled for 2010 - you can find out more here http://events.linkedin.com/Introduction-Anodizing-Workshop/pub/197688
We'll be taking this course on the road, and will cover most of the country - so chances are that we'll be to a town near you soon, and I hope to see you there.
Also don't forget to check out my article on the front cover of the Finishign Talk newletter. Click here to get a free copy of the issue Finishing Talks 1 Newsletter in 2010.
If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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First Anodizing Workshop in 2010
If you didn´t get the chance in 2009 to attend any of my anodizing workshops, THEN you should attend one of the anodizing workshops in 2010. You will have the possibility to join the workshop in the end of January in Phoenix, AZ and a lot of other places during 2010.
So if you still want to get more educated, increase your knowledge about anodizing, get new ideas, understand what happens when problems occur during the anodizing process and talk with a lot of other anodizers from around the US, the possibility is still there.
These anodizing workshops are a cooperation between The International Surface Finishing Academy and AluConsult, world leaders in the area of education and anodizing.
If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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So if you still want to get more educated, increase your knowledge about anodizing, get new ideas, understand what happens when problems occur during the anodizing process and talk with a lot of other anodizers from around the US, the possibility is still there.
These anodizing workshops are a cooperation between The International Surface Finishing Academy and AluConsult, world leaders in the area of education and anodizing.
The outline for the two days anodizing workshop is as follows, changes can happen during the days depending on the individual attendees need.
If you find this article useful and you would like to know more please contact me blog@aluconsult.com
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Hard anodizing of high silicon containing aluminum alloys by pulse anodizing
Sometimes pulse anodizing seems difficult to figure out, specially for the aluminum alloys which are difficult to anodize.
So a question about Hard Anodizing an aluminum alloy with 10% silicon aluminum Alloy to 75µm thick layer with a pulse rectifier, suggesting the current density per square feet will get the following answer.
To get 75 µm you can use different kinds of electrolytes; a suggestion would be an electrolyte with 15wt% sulfuric acid at 54 - 60F or one created from sulfuric acid and an organic acid at a lower or same temperature.
With the sulfuric acid electrolyte established you should then proceed to use 40 A/ft² for the high current density period and 10 A/ft² for the low current density period. Then depending on the geometry you should try different pulse periods. My suggestion is to start with 60 seconds in the high current density period and 20 seconds in the low period.
It is important to remember that a pretreatment with fluoride will improve your result.
Also remember that lower silicon content will give you a possibility to use a higher current density in the high current density period.
Use higher temperature than conventional hard anodizing when processing high silicon alloys, you could try using a high current density period of 20 - 100 A/ft², and pulse periods t1=t2=30 seconds.
You should always consider starting your test runs with voltage controlled anodizing, high current density period 20 - 40V and low 15 - 25 V.
If you find this article useful, Anne Deacon Juhl is available for consulting, please send an inquiry to blog@aluconsult.com
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So a question about Hard Anodizing an aluminum alloy with 10% silicon aluminum Alloy to 75µm thick layer with a pulse rectifier, suggesting the current density per square feet will get the following answer.
To get 75 µm you can use different kinds of electrolytes; a suggestion would be an electrolyte with 15wt% sulfuric acid at 54 - 60F or one created from sulfuric acid and an organic acid at a lower or same temperature.
With the sulfuric acid electrolyte established you should then proceed to use 40 A/ft² for the high current density period and 10 A/ft² for the low current density period. Then depending on the geometry you should try different pulse periods. My suggestion is to start with 60 seconds in the high current density period and 20 seconds in the low period.
It is important to remember that a pretreatment with fluoride will improve your result.
Also remember that lower silicon content will give you a possibility to use a higher current density in the high current density period.
Use higher temperature than conventional hard anodizing when processing high silicon alloys, you could try using a high current density period of 20 - 100 A/ft², and pulse periods t1=t2=30 seconds.
You should always consider starting your test runs with voltage controlled anodizing, high current density period 20 - 40V and low 15 - 25 V.
If you find this article useful, Anne Deacon Juhl is available for consulting, please send an inquiry to blog@aluconsult.com
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