Quick question on "old" ano method......

[Sid03]

So, how do you detect PAR with 2000series? Will the voltage stop dropping? As for temp. control......I got a larger container to sit the ano tank in. Going to add water and some ice.....just have to play around and get a feel for how much ice to add right before starting to anodize I guess.

As for ventilation.....any tricks of the trade for that? I do have a wall mounted ventilation fan but it isnt keeping up. I was thinking of having a fan near the ano tank to suck fumes into a dryer hose and run that hose up to the wall vent. Think that would be enough? How lethal are sulfuric acid fumes?

Also, I do alot of 2 color parts. While doing the second color on a part I can see the already colored side starting to dry. Is it bad to let it dry? I try to keep it wet by spray with water every once in awhile......does it matter?

Thanks

[Fibergeek]

I doubt that you will be able to detect PAR if you are using racking, the rack's resistance will hide it from you, I would expect this racking any alloy. Use the 720 rule.

In my setup; I use a 1/4 HP modified aquarium chiller in series with a 420 GPH pump, this combines the cooling system with the agitation system, it works very well. My tank uses 5 gal. of electrolyte, the chiller can maintain a 32 deg. bath temp, with 300W of electrical power being dissipated in it (hardcoat experiments).
Agitation (recirculating the electrolyte very fast) has an advantage over aeration (air bubbles) in that it generates little to no acid mist. This will greatly reduce the ventilation issue all by itself.

Sulfuric acid fumes are both toxic and corrosive, and not only to you. It will rust anything ferrous in the same room in time.

You will want to keep your anodized parts wet until they are sealed, it does matter. A spray with water periodically should do it.

[Fibergeek]

Hey guys, we put together quite a thread here today.

[Sid03]

Hey guys, we put together quite a thread here today.

Well, I seem to be making headway over here. So, you dont think there would be a difference from using one 8X8 cathode to using 4 of them since im using CC anodizing? Keep in mind im doing about 150sq. in. batches at this time.

Also, I would love more info on your chiller setup if you wouldnt mind. I like the circulation pump idea, other then the fact that I could picture a hose breaking somewhere and shooting acid all over my workshop. I remember some people having problems with the pumps burning up in the sulfuric acid and grease from the pump making its way into the ano bath. I would consider a system like yours, if it doesnt break the bank TOO bad

[Fibergeek]

Cathode Area:
An easy way to check this to get your setup working with your usual 4 plates, and wait 10-15 minutes until some anodize has formed and the voltage starts to settle down. Note the voltage and current. Then remove or disconnect one plate. You should see the voltage go up a bit, but the current stays the same. Then do the same with another plate. If the current does change, it indicates that CC control has been compromised. The difference in voltage is proportional to the increase in power dissipation caused by the reduction in cathode area in the anodizing circuit.

Power (Watts) = Volts (V) x Current (A)

I should have thought of this earlier, this will tell you about how much the racking is compromising CC control. If you see little or no change in current with less cathode, the only electrical downside to racking is the added power dissipation. If you see a substantial change, you probably have a problem. M_D should try this too, its quick, easy, and will disrupt your operation for only a few minutes.

I'll describe the pump and chiller I'm using later.

[Sid03]

Would you see any current change since your using a CC supply? Only the voltage will change to compensate for the current change....right?

[Fibergeek]

Right.
CC means Constant Current, the PS is holding the current constant and varying the voltage as the load changes. CV (Constant Voltage) does the opposite.

This simple test will indicate how much the racking is interfering with CC operation. The Ti racking will have some adverse effect on CC operation, because it doesn't anodize with the aluminum. This test should give an indication if its actually bad enough to be a problem. You should do this with a typical batch size, since this counts too.

Do the test, and post your voltage and current readings (before removing a plate and after) and I'll walk you through the math.

[M_D]

I may be able to try that today. My cathode area is pretty large (at about 7 square feet) each compared to the batch size.

The 2011 voltage curve falls off a lot more in our setup when compared to 6011.

One thing I have done to expedite calculating "optimum" anodize times is to load up a rack of parts, and pull one off every 5 minutes or so (and adjust the current accordingly). Then they can be layed out and compared after they are dyed and sealed. It graphically illustrates the difference, the first ones take longer to dye and don't reach the color depth, then they dye progressively faster and deeper, and one anodized beyond that for long enough you can see the effects of too much anodize time.

[Fibergeek]

M_D,
Even with cathode area that much larger than the work you should still see a change in voltage when you disconnect 1 plate, probably not as much as Sid. Ideally the voltage should go up, and the indicated current should remain the same. Kindly post your results also.

Your 5 minute staggered testing would be cheating in true Kentucky Windage anodizing, good idea.

[M_D]

I didn't have time to experiment today. I did read somewhere that the distance between the work and cathodes would change the required voltage. So this past weekend I was moving the racks closer to one side, about 6-7" off center from the vertical cathode sheets, and the voltage would go up 2 or 3 tenths (was running in the 17 V range). So I imagine taking one out would change it allright. I may have time to disconnect one cathode tomorrow.