Anodizing calculations (720 Rule)

[sswee]

dmiom,
Good detailed info but you might have overlooked that his PS has a 15V max. A CD of 6ASF is the highest capable at optimum conditions. Any resistance due to connections, temperature or other parameters will max out the PS.
SS

[bomscho]

did anyone rehost the .xls calculator? maybe this will spare someone answering the thread i just posted about wandering amperage

though i'm not sure how to apply this to odd size parts, e.g. a tube with an irregular solid bit fused to the top. both inside and out anodize and take dye and make the math agony

[bomscho]

woop! don't remember where i found this (dang got too many tabs open) but here's the calculator, as html so you can save it and use it always.

720 Rule Anodizing Calculator

thx

[stayhi]

Originally Posted by sswee

Yes on the area of the part. Racking very seldom needs to be considered.SS

sorry for the noob question, but say if you were taking racking into consideration, would it only be the submerged area?


also, with my 30v Mastech CC PS would i be able to speed up the process[where part size allows] or should i just stick w/ 6amps?


been reading this site like a madman this past week. ive concluded youre the guy to go to for answers though i gotta tell you I really appreciate all the help youve provided me just w/ posts on other peoples threads.

[BobFrapples]

Yes racking needs to be considered, but only the submerged area (if any).
If your racking is above the electrolyte and simply Ti Wire suspends your parts in the electrolyte, then do not take the racking into your calculations.

You can speed up the process. The higher CD you have, the faster the layer will build. However, this causes more heat, higher voltage, higher amperage, and needs more agitation.

[stayhi]

Thanks Bob. I figured with only the wires submerged compensation wasnt necessary. just had to make sure.

any recommendations on where to get Ti racking supplies online? the cheaper the better i can fab up my own racks, just have a hard time finding the stuff down here

[dmiom]

Originally Posted by stayhi

sorry for the noob question, but say if you were taking racking into consideration, would it only be the submerged area?
also, with my 30v Mastech CC PS would i be able to speed up the process[where part size allows] or should i just stick w/ 6amps? .....

Originally Posted by BobFrapples

Yes racking needs to be considered, but only the submerged area (if any).
If your racking is above the electrolyte and simply Ti Wire suspends your parts in the electrolyte, then do not take the racking into your calculations.
You can speed up the process. The higher CD you have, the faster the layer will build. However, this causes more heat, higher voltage, higher amperage, and needs more agitation.

Racking - I would add that the effect depends upon what your racking is made from.

If its from aluminium (which would have to have been stripped to ensure you got good electrical contact) then you need to take the racking surface area into account.

If you are using Ti racks or wire, then once they've been 'pickled' (recent discussion on the board e.g. in here) then their effect is negligible and you can usually completely ignore the SA of the racking (although if the SA of of your Ti racking was say 20 times greater than the SA of your workpiece you might have to make allowance ...)

Current Density - as Bob says, running at a higher current density than the 4.5 - 6 ASF range used in basic LCD (Low Current Density), you will introduce more heat. There will be two results - firstly, the 'bulk' heat of the electrolyte will give accelerated dissolution and a poor coating, and you'll end up with a chalky surface. Typical results are that it looks OK when pulled out and rinsed from the electrolyte tank, looks OK when pulled out from the dye tank, but as soon as you DI rinse it, you may see some dye leaching out. Then, after sealing, if you go to wipe it after spraying/dipping in WD40, you get dyed coating coming off like soot on your towel or cloth. If you cannot reduce your current density, the answer for this is both circulation and, if necessary, chilling. The second effect is increased risk of 'micro hot spots' which, as acidrain has explained on here, can lead to hydrogen bubbles building up on the surface - and for that reason, many run aeration still as well as agitation/circulation. Would suggest get your whole process working reliably using the LCD method first, and then try higher current densities etc.

Originally Posted by stayhi

Thanks Bob. I figured with only the wires submerged compensation wasnt necessary. just had to make sure. any recommendations on where to get Ti racking supplies online? ....

Sources for Ti racking - if the items are small and suitable, 1/8" Ti rod bent into an appropriate spring shape with plenty of pressure gives great results. If you search here in the forum you'll find lots of discussion & advice on racking. For bigger items, I can do no better than recommend the range of clips from ServiSure - e.g. look at the clips of page 16+ of their online catalog (we've no connection with ServiSure - just satisfied customers). Not sure where you're situated "down here" but I imported trans-atlantic from ServiSure and it was worth every penny in terms of predictable results.

Dave

(p.s. If you've any more questions on the racking, aeration etc. itself , can I suggest posting a fresh question rather than here in the 720-rule thread).

[stayhi]

that pretty much covers what i was looking for, posted here as everything asked applied to the thread and wasnt covered yet.[for noobs like myself]

"here" is honolulu so Mahalo for the help, ill go check out airgas tomorrow, but i dont think they stock Ti rod. Mastech arrives wednesday so my annoying noob threads in the weeks to come

[saintrich]

I have read the post on the 720 Rule and I still don’t know how to figure out the surface area sq.ft.
I’m wanting to anodize a gun receiver.
Can anyone help?
Rich

[sswee]

Start a new thread. What kind of gun receiver? Can you post a pic? Most of the calculations are basic. Can get you in the ball park.
SS