I just switched ti Ti racks, and had some surprising results

[acidrain]

Well, it's been kind of dead around the forum lately, so I thought I would share some resent upgrades I've done.
It all started with my cheap submersible pump that went out for the second time... they work OK for awhile, but failed (both times) right when I was going to do a job.
So... I picked up a nice Little Giant non-submersible pump off eBay for $80.
It's plumbed differently, so I had to re-do all that.
In addition I moved my entire system to a different part of my shop, built some nice benches, and built a new big combination heat exchanger/de-smut and degreasing station.
It is a welded aluminum tank, full of water and heated to 110F with a hot water tank element. It has places for a small tank of de-smut, and second small tank of SP degreaser. This all sits inside of a insulated plywood box. It maintains the heated liquids nicely.
In addition, the acid pump lines are routed through 3/4in PVC pipe, which is configured into a coil inside the heated water, and back into the acid tank.
The acid pump is controlled with a thermostat on the side of the acid tank. It maintains the temperature of the acid to within a couple of degrees of my target of 68F.
So now my de-smut, degreaser, and ano tank are temperature maintained.
So, about the Ti racks...
While the tank was down, I ordered some 1/8in Ti rod from McMaster Carr.
3ea. 6ft lengths of type 2 rod cost $82, plus shipping. Right after I ordered it, I found it locally at www.onlinemetals.com for half the price.
I was able to bend it into kind of a U shape to fit into the SS bus bars I use for racking. The bus bars have holes drilled every 2in. both vertically and horizontally so that they intersect. The horizontal hole is tapped, and a SS thumb screw is used to hold the racking wire.
The business ends of the Ti rods were bent into a modified U that acts as a inside clamp. I made them all the sizes that I need, along with some threaded ends. All for holding paintball gun parts. They work really nice.
OK, so now the title of the thread... a wierd unexpected observation:
My first run after assembling all this stuff, and making the new Ti racks was with a scrap. The process went perfectly, but I was surprised by the purple Ti rod (it came out anodized). Then I remembered that somebody said when you use Ti racks for the first time, you should pickle them by running them by themselves.
This made me think that If I did a large normal run, and used the one pickled Ti rack, along with the un-pickled ones, maybe it would affect the one part on the pickled one differently than the parts on the un-pickled ones.
So I ran all 18 feet of Ti racks all at once... by themselves at 6 amps CD.
I calculated the surface area of the parts that were submerged in the acid, and ran the calculated 1.5 amps for two hours. This is where it gets interesting: The volts curve acted like you would expect... quickly climbing to ~13v, except it didn't level off. The volts kept climbing until it maxed out my power supply at 31v., then switched from CC to CV and started dropping amps.
At the end of the two hours, the amps were at .1, and the volts were still at 31.
Lets see if I've interpreted this correctly:
The Ti racks have very little current loss into the acid, and therefore, need no special attention during normal ano runs. I don't need to add current to account for the different material... I just ignore the Ti.
Anybody back up those assumptions?
Sorry for taking you here the log way... It's been boring around here lately.

[sswee]

Is there ever an end to upgrading? I am just about to upgrade to a larger tank(again), a chiller, and Ti racks. I was told about the pickling of the Ti racks. If I remember correctly, the Ti racks can be ignored unless they are rather large and then you may have to add a little current if very much of them is submerged. I would not think your setup would need any consideration of the Ti, current wise. If there is no current loss to the electrolyte, will it still transfer power to the part? I would have thought it would have more than .1A .

If your pump is plumbed through your tank warmer and controlled with a thermostat, does it only run when a temp change is needed?
SS

[acidrain]

I ran some parts today, and couldn't be happier with the Ti. I don't know what took me so long (Oh yeah, cost :P).
Yes, the pump only comes on when the tank temperature falls.
Wierd thing about that... the tank temp. has been too high at times, and I assumed the thermostat was not sensitive enough, so I switched off the pump. I went to bed last night with the tank temp at 75F, and expected to wake up to a ~70F tank, but no... still at 75F. Then I realized that the convected current through the heating coils has caused a rise in temperature... Doh. I turned off the valve, ran my air agitation, and it cooled right down.

[sswee]

How was everything electrically compared to before Ti?

[acidrain]

This run was all 7000 series parts. Normally I run 6000 series, so I know the voltage will run lower than the 6000, but it was a little surprising. From memory:
Target CD- 6 a/sf.
Timed run- 90 minutes for a .75mil ano layer.
Voltage quickly rose to only 10+ volts, stayed steady for about 20 minutes, then slowly declined for ~1 hr. In the last 10min., voltage bottomed out at 5.5v, then began to rise again. Rose to about 6v+, then dropped a bit. Wierd.
The parts came out perfect... nice deep blue dye, and no burns at the contact points.
With the 6000 series, my voltage usually rises to ~12v-13v, then is level for the entire run. If I run to a full 1mil (2hrs), it will drop off a bit in the last 15min.
My next run will be with 6000 series. We'll see if the voltage is lower with that run.

[sswee]

How much of the Ti is in contact with the parts? Does the Ti have pretty good tension using it that way? I have used aluminum rod like that but didn't always have good tension on the part due to the grade of some of the rods.

Have you made any runs with your pump running much of the time. The reason I ask is when I ran aeration on 6000 series the voltage ramped quickly for 15 to 20 minutes then slow climbed for the rest of the run. After changing over to an acid pump for agitation with a very aggressive flow, the fast ramp of the voltage occurs in the first 5 minutes, then slow climbs for the rest of the run.
SS

[Sid03]

I mentioned before about the Ti racks. They actually call it "priming" the racks. The first time you use the Ti it will conduct.

In my testing I noticed exactly what you said.......no current is needed to add to compensate for the Ti racking. I followed the advise of somebody on here that used to swear that the Ti racking had to be compensated for, until I actually did some testing. The only time the Ti made a difference was if I ran a part on a Ti rack with alot more surface area.

I somehow figured that all the Ti rack manufacturers and anodizing specialist couldnt be wrong........they weren't.

[acidrain]

I don't use the pump for agitation... only heating/cooling.
I still use air agitation, and I'm happy with the results, so I've stuck with that.

Good to know Sid03.

Just for fun I'm going to run some samples... one batch of Ti racked parts, then a second batch of aluminum racked parts. I'll have those results in a couple days.

[rclint]

I just got my outfit going all the way as well, a 30 gallon igloo cooler, and a TE-5-MD-HC. It really moves the electrolyte, built a cart for my cooler, on caster so I can move it around. I want to tinker with the racking as well

I also noticed using the pump for agitation, the current ramp is constant, no matter if it's fast or slow, it may ramp fast then slow down, but no pauses. Using hand stir agitation is now for the birds, I should have got this going long ago.

Still working with cast, with agitation I notice much more even colors when dyed, I think using the agitation grows a more uniform anodize layer, but no way to prove that, I do know my finished work looks better with agitation.

I will check that link to the TI wire, the one thing I wished could be done is time, I know always something, if we could anodize a finished part in 30 mins it would really be a big step, but burning parts may be aproblem, and a power supply large enough to do this

Clint

[sswee]

Sid03,
When you said;
The only time the Ti made a difference was if I ran a part on a Ti rack with alot more surface area.
Did you mean running a part with less SA than the Ti rack?
SS