Anodize density

[jcmmachining]

This it to all that have a lot of anodize experience. I'm beginner and have the LCD system with the 20 amp digital rect., I have been doing jobs now for about 2 months and set my loads around 6-8 amps depending on the job size and the volts vary from 13 volts down to about 5 volts at times , I have to say that I'm not good with math on figuring out the SA, but i check the parts when finished and i use a volt meter to measure continuity show a high resistance the needle doesn't even move. now are the parts anodized or not. does the sealer put a coating on the part that will give me a high resistance. my racking is Ti and are not coated , the parts are small also. not like the picture before showing a Ti rack with washers but good size parts. some of my Ti racks have aluminum fingers and some have Ti fingers. I notice that the parts have to stay in the tank for 80 min. or i will get a continuity reading on the volt meter. i have not tried to set the amps higher for a lower anodize time. but always keep the parts in the tank for 80 min. How do i know if the part is under or over anodized. or are they anodized at all.

[sswee]

The only true way to know how the anodize coating is, is to measure coating thickness with a Eddy current meter. A meter too expensive for the majority. Parts anodized too long have a chaulky residue on them that can usually be buffed off if it's not to excessive. The cheap way to check the anodize, would be to dye a test part to see how the dye takes. The 720 rule has been proven and I haven't had any problems since I started using it for my setup. I could give you better figures if I had more info on your run. A amp setting of 6-8A at a current density of 4.5A calculates a surface area of 192 to 256 square inches. A 192 in sq SA at 4.5 CD calculates to a 6.0A setting for 84 min. to get .5 mil coating with a peak voltage of 11.25V. The use of Ti racking will change alot. You will need to up your current to compensate for the racking. How much will be dependant on the racking you have. If I remember right M_D uses Ti racking and can help in that area. From what I can see and calculate your probably anodizing too thin because of the Ti racking. Your current and times are good for wire hanging.

[acidrain]

You absolutely have to know the surface areas of your parts....
Length x width for square/rectangle areas,
Pi (3.14 inches) x the radius squared (radius x radius) for circular areas,
Pi x the diameter for measureing around a cylinder or round bar.
Don't forget to measure the insides of the parts too.
I ano mostly paintball gun parts, and have an accurate list of every part I've ever measured. Now when I do a job, I just reference my cheat sheet.

Also, the acid to water ratio for your ano tank, temperature of the electrolyte during anodizing, and target current density all have an effect on the quality of the results and how much voltage is drawn. If your ano tank is above 75 deg F., you may disolve the anodic layer as fast as it is grown.

M_D can speak to the Ti racking, but why are some of the fingers aluminum? You realize that any aluminum racking parts need to be stripped after each use.

Once you get your SA figured out, maintain exact electrolyte temperatures, and account for the surface areas of your racking system, I'm sure you will have much more consistant results.

[jamerson]

cheat sheet

I know you did all the hard work ,but is there any way you could e-mail me that list . I mainly anno raw shockers from sp.