[quote="Sid03"]M_D- thanks for the input.
I have been adding 1.5A to the current needed to try to compensate for the Ti racking. I may call the manufacturer tomorrow and see if I can get and exact surface area of the different clips im using. Do you guys think the exact surface area of the rack should be accounted for, or only a percentage of it since the Ti conducts differently? ………….quote]
I wish I could answer that with certainty, but I can only say that I don’t think you want to compensate for the Ti with the amps per square foot as the aluminum. We have been using the 720 rule for some time now. When I try different current densities, I use this factor to estimate the time needed to comparably match the thickness of parts done at another density. Right now, we are usually going to 600, which seems to be working well (parts are dying nice, and no real problems are evident). So if we are using 10 amps per square foot of parts, we anodize for 60 minutes (60 x 10 = 600). If we use 12, we go for 50 minutes (50 x 12 = 600), and so forth. On the 6061, for red we go a little longer to a full 720, and it seems to give a noticeable difference in the depth of color possible when dying red. It may not be the thickness per se that is helping; it may be the pore structure instead. I don’t know for sure why, it just helps.
One difference I notice between 6061 and 2011 is this; the 6061 seems to be more tolerant of “over” anodizing than the 2011. One thing that is puzzling though, is that 2011 doesn’t build the thickness as fast as 6xxx series. But if we anodize the 2011 at the same rate and time as 6061, it looks like a good match. There again, it may be the pore structure balances it out, rather than actual thickness. But, if we anodize longer than usual, the 6061 takes longer before it deteriorates than the 2011 does.
On some of our parts, the racks even exceed the total part area. If the Ti needed as much current as the aluminum, I think that we would be needing to add more current or add more time, if you compare the dying tendencies we see with Ti racking against parts anodized with aluminum hanging wire where the wire area is either insignificant, or calculated in and compensated for.
At some point, I will carefully do some identical parts with both aluminum and Ti racking, and see what I learn.
I know this is just general and highly unscientific, but it is working. The unfortunate thing about it is not being able to factor it all like the LCD instructions outline. If one were doing odd batches, where the part surface area to rack surface area varied constantly, then it might be pretty tough to maintain any predictability at all. As it is, we are using either a little different current or time for various parts, to compensate for the area ration between the racks and parts. It has been from trial and error, seeing the tendencies, and adjusting accordingly. That’s why Fibergeek has rightly referred to it as Kentucky windage.
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