Use of Titanium.

[usao]

Im considering using Titanium for both electrical and mechanical connections for my parts.
Does the Titanium surface area become anodized during the AL process and do I need to include the surface area of the Titanium supports into the amperage computation?

[M_D]

Re: Use of Titanium.

The titanium doesn't anodize with the same type of coating as aluminum, although the process can color it. Some people refer to this as anodizing, and I suppose technically it is. It only takes seconds or minutes, and by varying the voltage from about 17 to 70 volts it will turn colors right before your eyes. The color it turns depends on what the voltage is. Once it is colored with 24 volts for example, it can't be changed to the colors produced by a voltage lower than that, but the color can be changed to any color produced by a higher voltage.

The surface area of titanium rack does affect the process in anodizing aluminum. If it is a thin wire, where the surface area is next to nothing or quite minimal compared to the aluminum part, it can probably be ignored.

There is a thread at the top (sticky) entitled "The importance of good connections" that has some discussion on titanium racking that might be interesting if you haven’t read it already.

Link: http://www.caswellplating.com/bbs/viewtopic.php?t=2091

Where the surface area is significant, it appears the titanium robs enough current to be a significant factor, perhaps more so at low current densities than typical commercial anodizing current densities. Unfortunately, I can't give you any precise guidelines on how to factor it in, to where you can calculate it exactly like you would the aluminum parts if following the LCD instructions. One square foot of titanium wouldn't be equal to the same area of aluminum; I feel somewhat safe in saying that although it’s probably going out on a limb. For example, if you had aluminum parts totaling 144 square inches (1 square foot) and wanted to anodize at 6 amps current density, they would take 6 amps actual current (not the hanging wire or racking). If these parts were on titanium racking that also equaled 1 square foot (1 square foot of aluminum parts plus 1 square foot of titanium rack) my best guess would be to add 2-3 amps, and set it for 8-9 amps.

I have been using titanium racking for a few months, and at first didn’t appear to have any issues. The more I saw, the more I started to realize there might be issues. Now, I am virtually positive there are issues. Someone (I hate to publicly mention names without consent or prior knowledge, so I’ll leave it up to them if they want it known) who is more capable than I am in the electrical department has offered to help figure this issue out. Hopefully with in a few weeks there could be some more scientific data available than my “best guess” answer, although there is no guarantee of a simple answer.

[Fibergeek]

M_D is referring to me.
He volunteered to send me a a few pieces of commercial titanium racking. I'll do some controlled experiments with this racking and hopefully come up with some formulas to compensate for the current robbing, based on its surface area. I'll try to keep it simple, but we'll see what pans out.

[jtsuttle]

Hey Fibergeek,
This is a quote from the servisure catalog:
"Titanium racks don’t consume current as do aluminum racks. Therefore, you can use your rectifier to anodize parts, not racks."
Just thought it may help in your experimenting.

[Fibergeek]

I saw that bit of nonsense in the Servisure catalog; in order for titanium to not "consume current", it would have to be an insulator not a conductor. If titanium was an insulator, it would be worthless to make the anode connections to the parts, right? Fortunately for racking; Ti is a conductor (being a metal) it just doesn't conduct electricity as well as aluminum does. This means it "consumes" less current than aluminum racking.

Servisure's over-simplicification results in their attempting to violate Ohm's Law, and there are no exceptions to a Physical Law.

[jtsuttle]

I noticed that Caswell does not have the Titanium wires on their website anymore. I have a local welding supply that carries titanium TIG wire. What would be the best alloy to use with alum. anodizing? They have about 6 or 8 different kinds.

[Fibergeek]

The only case where Ti wire has any advantage over Al wire is when you intend to make the electrical connection to the work via spring tension. This is because titanium can be hardened and tempered to a much higher degree than any alloy of aluminum. With this in mind, you want Ti wire with the highest spring temper that you can find.

M_D has advised that the Ti wire Caswell used to provide is too soft to provide much spring tension. Ask your supplier to recommend an alloy with the best spring characteristics.

[jtsuttle]

Spring tension is exactly what I'm looking for; to hold tiny parts with no holes.

Should we not be concerned with other metals in the alloy contaminating the anodize tank?

Some alloys of titanium even have aluminum in them; would these partially anodize and have to be striped later?

What effect, if any, would deox/desmut have on titanium?

[Fibergeek]

Other metals alloyed with titanium are in very small quantities and are well mixed with the titanium, they will have very small to negligible effects. Titanium has excellent resistance to the nitric acid in desmut, no concerns.

M_D or another user of titanium racking could provide insight on whether Ti will require stripping after extended use.

[M_D]

The titanium racks won't need to be stripped. Servi Sure calls it spring grade titanium, they might be willing to tell you more specifics, this is their e-mail: [email protected]

[jtsuttle]

I have emailed servisure two times and they have not responded. Thats when I started bugging you guys. Thanks for your help.