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Aluminum and Titanium Anodizing Equipment – Can we use one line for both?

Aluminum and Titanium Anodizing Equipment

Since we are an anodizing equipment manufacturer for both aluminum and titanium anodizing, we have some potential customers ask us about doing aluminum and titanium anodizing in a single line (changing out chemistries, so not at the same time).  The two processes are different enough that the design does not lend itself well to do so, and here are a few reasons why.

Aluminum Anodizing Equipment

First off, let’s take a look at the processing steps for aluminum.  We’ll borrow a graphic from our article about “How to Anodize Aluminum” to review the process steps involved:

aluminum anodizing equipment process steps

Aluminum Anodizing Process Steps for Sulphuric Acid Type II Anodizing

 Listing the process steps without including the rinses that go with them, we see that we will require the following for aluminum anodizing equipment-

1. Cleaner

2. Etch

3. Deox

4. Anodize

5. Seal

Titanium Anodizing Equipment

Now let’s take a look at the steps involved for titanium anodizing equipment.  We will borrow another graphic to illustrate the process steps involved, but this time from an article about “How to Anodize Titanium”  from our website on that subject at http://anodizetitanium.com/:

Process Steps for Titanium Anodizing Equipment

Titanium Anodizing Process Steps

 Looking at the graphic and again removing the rinse tanks, you can see that the process steps for titanium anodizing equipment would have the following-

1. Cleaner

2. Etch

3. Anodize

Aluminum vs. Titanium Anodizing Equipment

Comparing the two processes, there are more process steps involved for aluminum anodizing equipment  (there is a deox step in aluminum anodizing but not in titanium anodizing, and usually a sealing step as well) which would require additional anodizing equipment.  What is not shown in the charts is that different chemistries are used to anodize aluminum than those to anodize titanium, and those different chemistries have different operating temperatures. 

As an example, the etch for aluminum anodizing is usually done with 140 to 160 degree F sodium hydroxide, which will attack the surface of the aluminum.  This would have little or no effect, though, on titanium parts.  To etch titanium, a much more agressive etch chemistry must be used, usually containing nitric acid, ammonium persulfate or ammonium bisulfate in combination with ammonium bifluoride or hydrofluoric acid, and these chemistries can be anywhere from ambient up to about 140 degrees F.   The etch for titanium will be very reactive with carbon steel or stainless steel, which are often used as the material of construction for aluminum etch anodizing equipment  (even polypro would likely have issues with the titanium etch at operating temperature, which could be used as an alternative material to use for aluminum etch anodizing equipment).

Because of the different chemistries and temperatures involved, we would usually use different tank or tank liner materials, as well as the heater and the pump materials of construction.  Plus, the rectifier voltage and amperage requirements, the proportion of cathode-to-anodes, the cathode materials, and the increased DC cable and contact requirements for aluminum anodizing would make it difficult to design a line to do either process well, and yet do the other process efficiently, within the same anodizing equipment.

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