Why does my math not jive with 720 Calculator?

[RedRiver]

OK...Here we go, buckle up!

I know this seems elementary to many of you and in all honesty the 720 rule is no mystery to myself. In an attempt to better understand the calculation of PAR, however, I have chosen to omit nothing and show my proceedure from start to finish. Please, correct me if I am wrong!! I feel that I now have a handle on it, however, I may still be "out there"...So let me know.

As I have come to understand it over the past few days, in theory, I could mathematically calculate my entire anodizing process using the 720 rule and PAR as follows (assuming that I am working within a perfect environment) :

Parameters within my anodizing line (the constants) :

- Electrolyte contains a 9.4% (by volume) sulfuric acid content.
- Electrolyte operates at a consistant temperature of 70F.
- A current density of 12 ASF is always utilized.
- 0.95 Ohms of resistance per 1 square foot of surface area being anodized.

Parameters within my anodizing line (the variables) :

- Surface area is part/batch specific.
- Coating thickness is decided upon prior to anodizing.
- Total current will fluxuate in direct relation to surface area.
- Duration will fluxuate in direct relation to coating thickness.

Utilizing the Above Data in a Theoretical Situation :

Instructions to the Anodizer :
- A coating thickness of 1 mil is to be achieved.

Define the Variables :
- Surface Area of 1 part = .383 sq.ft. (This must be phyiscally measured)
- An entire batch contains 5 parts.

Do The Math :
Total Surface Area = (Surface Area of 1 Part) x (Number of Parts)
Total Surface Area = (0.383) x (5)
Total Surface Area = 1.915 sq.ft.
(Surface area of racking materials has been omitted from this example for the sake of simplicity)

Total Amps = (Current Density) x (Surface Area)
Total Amps = (12) x (1.915)
Total Amps = 22.98 amps
(Adjust your constant current power supply to 22.98 amps)

Duration = (720) / (ASF) x (Thickness)
Duration = (720) / (12) x (1)
Duration = 60 minutes

Calculate PAR :
PAR = (0.95) / (Surface Area) x (Total Amps)
PAR = (0.95) / (1.915) x (22.98 )
PAR = 11.385 volts

[sswee]

You pretty much got the cat by the tail.
A quicker way to figure peak voltage by Ohm's law
V = I * R
12A * .95O = 11.4V
SS

[RedRiver]

Cheers!!

Thanks!! You've been outstanding SS. Pat yourself on the back for me.

- Dan