Hardcoat Anodize

[kparham]

I seem to read a lot of information regarding the advantages to anodizing by current density than by voltage. Of the material I've read there is always a ramp rate given for voltage anodizing but no ramp rate for current anodizing. So my question is this, does the current need to be regulated by a ramp rate,
and if so how will the time to ramp influence the thickness calculations.


K-man

[sswee]

I am not familiar with the specifics of ramp rates for voltage anodizing. I have been taught to anodize with current density by Fibergeek and M_D. Following the 720 rule, that states that a 1 mil coating can be grown in 720 amp minutes at a 1A CD, to make the needed calculations for run time. Calculate the surface area(SA) and the needed current for the desired CD. The needed current is set on a CC capable power supply. The PS ramps the voltage to maintain the desired current giving a more even growth of the coating. The ramp rates vary with the kind of material, acid concentration, tank temps, and a few other variables. This is the benefit of CC anodizing. It compensates for many variables.

As to your question directly, using a CC capable PS the ramp rate is automatically controlled as needed by the PS. If your using a method or PS that is not CC, you need to constantly adjust the voltage to maintain a CC. Anodizing by voltage, the parameters of a setup need to be controlled more.

If there are any more questions, just ask. SS

[blackcote]

Originally Posted by sswee

...you need to constantly adjust the voltage to maintain a CC. Anodizing by voltage, the parameters of a setup need to be controlled more.

So just thinking out loud here... I have something I want to try. Do you know what parameters need to be controlled more precisely in CV anodizing? Or what parameters can be more relaxed in CC anodizing? I guess that's the same thing, but I think you get the point.

[sswee]

From what I've read and conversations with others, tank temps should be held closer although I don't remember what is optimum. The acid concentration and the aluminum content of the electrolyte. Basically the parameters are the same, it's just the ranges or tolerances of each are much more relaxed in CC because the PS automatically compensates for the variances. I don't know if I answered any of your questions. It's been awhile since I went over anything on CV anodizing. I would be interested in what you found on the ramping in CV anodizing. I never did find much on the subject. Feel free to email me direct.
SS