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Barrel / Basket / Bulk Anodising

RFQ: Searching for company/person in Europe having knowledge/business setup for bulk black anodizing small aluminum parts in vast volume (millions). Yes, minor aesthetic issues are okay ...

Mate Gal
- Hungary
September 22, 2022
    privately respond to this RFQ   ^
Ed. note: As always, gentle readers: technical replies in public and commercial replies in private please (huh? why?)

Need supplier for bulk anodizing small parts in Europe

RFQ 20-50 mm aluminum parts needed to be black anodized, mainly for aesthetics. Small flaws ok...
Volume is millions of Pcs per month.

Mate Gal
- Hungary
September 22, 2022
    privately respond to this RFQ   ^
Ed. note: As always, gentle readers: technical replies in public and commercial replies in private please (huh? why?)

⇩ Closely related postings, oldest first ⇩

Q. Hello,
I am a graduate chemical engineer and have been working for an anodising company for 18 months. We anodise components for the Cosmetic industry, so, quality surface finish is paramount.

I have been asked to investigate barrel anodising. I understand the quality will not be as good as our rack anodising, but how do you barrel anodise gold without having lots of touch marks on the components? Is there a high level of rejects? Any information would be most helpful. Thank you.

Jonathan Holgate
Lancashire, UK

A. You cannot use a barrel to anodize!

You have to have excellent contact or the parts will make and break the connection and arc, destroying the parts. What you may be referring to is for small parts, they stuff them in a special titanium tube with lots of fine holes and literally squash the parts with a nut on the lid. You will have lots and lots of contact points that will show. Definitely not for a cosmetic finish.

James Watts
- Navarre, Florida

"The Surface
Treatment &
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Aluminium and
Its Alloys"

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A. My company does all types of anodizing including BULK. You absolutely can anodize in a basket. We have done this for over 40 years & while, yes, you will have touch marks, many cosmetic parts are done in bulk anodize. Bulk anodizing is a specialty and the more experience you have doing it...the better the results.

David A. Kraft
- Long Island City, New York

A. Dave, My reply stated that you could do parts in BULK. The original letter stated that his parts were for the cosmetic industry, not cosmetic parts. Will you buy your best girl a compact that has a nice touch mark on the cover versus one that does not have any?

I have never met a customer that would accept contact marks anywhere but where it was covered by another part. The paintball industry will not accept it, the military generally will not accept it, the auto industry generally will not accept it, the archery industry will not accept it, the bicycle industry will not accept it, the electronics industry generally will not accept it, so, who will accept it on other than screws? Especially the COSMETIC industry.

James Watts
- Navarre, Florida

A. This one is clearly loaded with semantics issues.

Some of us may be picturing a plating barrel when Jonathan says 'barrel' -- but perhapshe may not care whether it's called a barrel or a basket or a rose as long as it permits bulk anodizing.

Then we have the term 'bulk', which to most people certainly induces visions of large containers of randomly oriented small parts which will make contact with each other, and consequently leave touch marks, at numerous points.

Then we have the question of 'cosmetic industry', which Mr. Holgate defines as a field where "quality surface finish is paramount".

My own feeling is that the chance of this project being a success is slim when he says quality surface finish is paramount though.

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

A. The shop where I once worked used to bulk anodize pencil ferrules (the metal band that holds the eraser) by the millions, when pencils were still made in the U.S. We bright dipped and gold anodized a large number, but the most popular color was Eberhard Faber's premium pencil, on which the ferrule was anodized black, where contact points would have been most noticeable. But contact points were not as much a concern as a lot of other issues. You obviously can't anodize in a traditional plating barrel, but you must use titanium baskets. Parts must be packed as tight as possible (An amazingly small percentage of parts bend). A doughnut-shaped basket is best for maximum circulation and best color uniformity, as you are packing a lot of surface area into a small, confined basket, hence a lot of amps, and hence a lot of watts of heat are generated, which can give you shades of gold across the whole dark-to- light spectrum.

Other problems include: Rinsing, rinsing, then more rinsing. Parts are best processed loose in all tanks except anodizing. Solution control is highly critical through the whole line. Load- to- load color matching is not at all easy.

We had to use an almost full-time inspector to pick out voids and bent parts (mostly voids), as no matter how hard you tighten the baskets, some parts will be loose.

The process is as much art as science, as in many types of metal finishing. Before you go out and buy the equipment to get into what can be a nightmare, I would recommend you have David or some bulk anodizer in your country anodize a drum full of your parts and send you back the loads uninspected, so you can see what to expect.

phil johnson
Phil Johnson
- Madison Heights, Michigan


Look into this for a way to keep rack plating your parts, but doing the racking and deracking at least twice as fast as by hand. Endura Corp. in Nokomis, FL builds a real neat racking machine. If you combine this with a modified multiple insert rack that I think Vulcanium makes (possibly Servasure) you should make life on your rackers a lot easier as well as a lot faster. I would guess that it could easily reduce rejects also. Really sounds like a win-win situation.

PS, both Endura and Vulcanium will be at Sur-Fin next month, so you could get hands on trial and face to face contact as to your needs. Sure beats faxes.

James Watts
- Navarre, Florida

I'm going to back James on his statement, Dick at Endura has an excellent machine for fast, production racking and unracking of small parts on compatible racks (he makes plating and painting racks too). Call him and ask him for the video he has, it shows you, in real life examples, how well this setup works. The cost around 5K for a manual machine and around 6-7K for a hydraulic. He stated to me at one time that if you have a lot of work that someone would be better off using the hydraulic units, less stress on the body = 's less fatigue = more production = more profit. Simple equation, wonderful idea. If I had a use for those things, I'd snatch a group of them up in a heartbeat.

Matthew Stiltner
- Toledo, Ohio

A. Mr.Holgate, You may consider the cold chemical oxidation of aluminum, a process (known as Decoral) which produces a 1 to 2µm thick transparent aluminium oxide film that can be coloured and works in slow rotating polypropylene barrels.

Emmanuel Popesco
- France

Ed. note: Readers, you can read about the Decoral process in topic 2951, "Non-electrolytic blackening/coloring of aluminum: Decoral process"

Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

Q. I am looking for information on basket anodizing.I am interested in knowing if it is possible to get a high quality finish with the ability to dye various colors with the basket anodizing process.

Scott Ebert
- Fridley, Minnesota, USA

A. Basket anodizing is going to have one or more contact marks with zero anodizing and thus zero dye. I do not think that this meets a normal definition of high quality. There are many kinds of tips for anodizing racks. Some are amenable to loading machines. while it does not meet the speed requirement, it will produce a high quality part and probably much faster than what you are currently using.

James Watts
- Navarre, Florida

A. A variety of colors, yes. High quality, maybe, depending on the particular parts and the experience level of the anodizer. You'll have more, and more random, contact marks, and you may have some difficulties getting consistency.

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

A. Ability to dye - YES. High Quality - No.

All the rack manufacturers, some listed in, sell baskets which tightly clamp small parts in a basket. Except for contact marks which will remain bare, the parts on the outside of the basket will get a good anodic thickness with ability to absorb dye. The parts closer to the inside of the basket will not get as much thickness as a function of current distribution and solution agitation.

Basket anodizing is suitable ONLY for color coding small parts and fasteners, leaving some lack of uniformity and a bare contact mark(s) on each part.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina

A. Scott,

The quality of basket anodizing does depend upon the configuration of the part, but that being said it is very possible to get a high quality finish on certain parts using basket anodizing. Furthermore, because of the bulk processing aspect, it is possible to do this at a much lower cost and shorter turn-around time then with conventional rack anodizing. Once anodized the parts can be dyed in the same manner as any other anodized part. Contact marks are left undyed, but (depending on the configuration of the part, parts with many or large flat surfaces are not good candidates) typically are very small and insignificant.

My company specializes in the bulk anodizing of fasteners in the aerospace and automotive industries. We are QS 9000 certified and regularly provide a very high quality and consistent finish. Please feel free to email me if you are interested in further details.

Jim Gorsich
Compton, California, USA

A. I agree with Mr. Gorsich that it's a question of what you are looking for and that a few contact marks don't obligate us to call a finish low quality. After all, virtually every plated or anodized part has at least one contact mark. If it was a watch case, contact marks would probably condemn it as low quality; but I have seen products such as hose barbs bulk anodized and they were fine for their purpose.

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

thumbs up signThank you! for your responses. I appreciate all of the input on this topic. I am looking for a jewelry like finish, with consistent color and no visible racking marks on the exposed surfaces. By your answers I surmised that basket anodizing would not work for this situation. Thanks again!

R.Scott Ebert [returning]
- Fridley, Minnesota, USA

Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

Q. We are looking for a process to anodize small, 1 x .750 x .375 t shaped, Aluminum parts in house. We are looking to do about 150000 per week. Currently using chemical conversion with zinc phosphate that is waxed but it is not being consistent. Exterior part - needs to last. Prefer anodizing.

Jim Guffey
- Perry, Kansas, USA

A. You have not given us enough information to give a good answer. Anodize will cost more than phosphate! Your part is small so is going to be a little bit tough to rack. You might do basket anodizing, but you will have several contact points of various sizes on each part with no coating. Several anodizing choices. type 2 which is regular sulfuric anodizing, type 3 which is hard anodizing or what we refer to as type 2 1/2 which is a poor man's hard coat that is done with an additive and a higher temperature.
This quantity is not to be taken lightly for in-house work. You will need a significant dedicated facility. Can you run 24/7 or 24/5. If so, it can be downsized appropriately. Always leave room for increased production at a later time without a major rework of the facility. since you are going to generate chemical fumes and a lot of moisture, even with a good exhaust system, it should be physically separated from the machining operation. Very doable, but not something that you jump right into without hiring a consultant or a very broadly based anodizing foreman and listen to him/her. A lot of engineering items to look at.

James Watts
- Navarre, Florida

A. Perhaps you can tell me what machines I need to make the parts; I'm sure, just like you envision anodizing as simply "dipping", making the parts is nothing more than cutting up sheets of aluminum with tin snips and then bending them up with pliers (or something like that). Except that federal, state and local regulations on air emissions, discharging rinse water, hazardous chemicals such as concentrated sulfuric acid, and resulting hazardous wastes make the proposition of your anodizing much more inconceivable than my making machined aluminum parts! All kidding aside, you stick to "whittling" parts and I'll stick to "dipping" them. There are a number of good anodizing job shops in the mid-west which can be found at this website or other finishing based sites.

milt stevenson jr.
Milt Stevenson, Jr.
Syracuse, New York

A. Bulk anodizing is perfect for that type of scenario, but I can't tell from your description whether your part is perfect for bulk anodizing or not. Because the location of contact marks can't be controlled during the bulk process, the best results are obtained with parts that predominantly curved surfaces (for example, rivets and screws - a combination of which my company does between 2000 and 4000 pounds per day).

I'm going to try to give you a call to offer a quote, but if for some reason you don't hear from me, please contact me through the link below.


Jim Gorsich
Compton, California, USA

Q. I want to start Anodizing specifically for Aluminum pencil ferrule in different colors please guide me with the process. Also if there is any other process to get different glossy finishes in different colors on aluminum.

Sohil Sheth
metal finishers - Gujarat, India
September 24, 2013

Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

Q. I have a need to anodize several thousand stamped aluminum parts of the following size: 1-1/2" diameter 1/16" thick.

I'm not expecting a perfect finish on these parts but I would like the whole part to take some color.

Can I expect to achieve these results through basket anodizing?

Thanks in advance for any suggestions.

Brandon Carrere
- Houma Louisiana USA
January 9, 2015

"I'm not expecting a perfect finish on these parts but I would like the whole part to take some color."

A. It depends. If they are flat parts, say washers, which will lay together, the answer is, probably, no. On the other hand, if they are formed enough that they make only point contact, the answer may be yes.

You'll have to try it and see.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina
January 9, 2015

⇦ (tip: readers rarely show interest in abstract questions, but people's actual situations usually prompt responses)   smiley face

Q. How to do Anodizing for small Parts size about 1mm x 1 Length
Please suggest best method?

Shalem Raju Bhavigada
Employee - India
March 13, 2020

A. Hi Shalem. Bulk/basket anodizing is surely the cheapest method, but there would not be other methods if one way was "best". It always "depends" (on factors you haven't told us yet)  :-)

How many parts do you have to do, what alloy are they, do you need dyed or non-dyed, how thick must the anodizing be and why, what reject ratio is acceptable? Please send a photo or drawing of the part to for posting here, then hopefully the readers can suggest whether bulk/basket anodizing is worth pursuing or the parts must be racked. Thanks!


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
March 2020

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