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Anodising
| Terryd | 29/03/2010 16:02:05 |
 1946 forum posts 179 photos | Of course mgj, I should also have pointed out that when using washing soda basic protection is needed. Thanks for rectifying my omission. Best regards Terry |
| Allen Paddock | 30/03/2010 08:29:18 |
| 24 forum posts | All this talk on anodising reminds me when i worked at at factory called SONA or NC Josephs at Stratford on Avon before it closed down,(( They made tea pots coffee percolators saucepans sugar bowls etc etc all anodising )) I was a maintenance fitter there, The anodising vats were about 40 feet long filed with very hot acid and every Friday we had to drain out the acid put wooden props in the center of the vats on to hold up the agitating mechanism and clean off old lubrication and reapply with new oil ,,It was a really hot smelly job working over the acid tanks as there was always about a foot of acid still in the bottom i hated doing that job. NO safety equipment..Ah memories !!! |
| mgj | 30/03/2010 08:53:51 |
| 1017 forum posts 14 photos | Have I been a bit dim - not knowing a great deal about anodising, or how they degrease ali comercially.? Be warned, both caustic and soda pit ali very aggressively. Soda I know from cleaning flesh off bones boiling up in an ali saucepan, which started to disappear slowly. Caustic from work where we use a .5-1% solution for cleaning pipes. A welder made a stand with ali treads, and the once daily overflow from one wash disappeared a complete 1/4" ali tread plate in less than a week. So you might just get your etch and degrease all in one!! Might be wise not to dawdle while degreasing! |
| Les Jones 1 | 30/03/2010 09:47:56 |
| 2292 forum posts 159 photos | In the process of aluminium dissolving caustic soda (Sodium hydroxide) hydrogen is given off which would be a fire / explosion risk. I would think a brief dip in the caustic soda would be OK. Les. |
| Gordon W | 30/03/2010 10:24:05 |
| 2011 forum posts | I'm no expert in alloy cleansing, many years ago, trying to clean old castor oil off a BSA Gold Star rocker cover with hot caustic soda left it to long, no rocker cover. I found by accident that washing powder ( the stuff that goes in washing machine) in hot water is a good cleaner for ally, have boiled up and recovered a 50 yr. old carb. recently. Also cleaned a silver soldered brass boiler and a S/S silver soldered displacer, very effective. This stuff is hard on the skin and of course wash afterwards. Hope this might be of use. |
| David Clark 1 | 30/03/2010 16:43:36 |
 3357 forum posts 112 photos 10 articles | Hi There
Check out the digital free copy of Model Engineers' Workshop.
It has a good article on anodising.
regards david
|
| Ramon Wilson | 30/03/2010 22:30:32 |
 1655 forum posts 617 photos | Thanks David, Another good article. I think it fair to say I'm now well versed in what to do with all the super help and advice I have recieved. The parts are underway and I hope to be setting up to have a go next week - weather permitting that is!
Regards - Ramon
|
| ZigFire | 30/03/2010 22:35:58 |
| 32 forum posts | Hi Ramon, Just one thin I meant to mention, no matter what anodising process you use, the result will ONLY be as good as the finish on the original parts. Anodising will not "cover up" any poor surface finishes. The better the surface finish the better the anodising result.
Cheers Michael |
| Ramon Wilson | 31/03/2010 11:50:05 |
1655 forum posts 617 photos | Thanks Michael, Yes I was aware of that - I'm taking care not to get any of the parts so far made scratched or dinged. Nearly there, just the cyinder fins to do today.
regards - Ramon |
| thomas oliver 2 | 04/04/2010 22:36:55 |
| 110 forum posts | Try this site for info.on anodising - it is about 33 pages to download, and is commercial but covers the subject adequately. --- www.focuser.com/atm/anodise/anodise.html |
| Ramon Wilson | 04/05/2010 12:28:34 |
1655 forum posts 617 photos | Hi again,
I now have some results - not great - but at least something to report.
First off though I'd just like to say thanks to all of you who have responded so far, your input is much appreciated.
I finally cobbled together the neccessary items to have a go at this process and have jury rigged a set up using a 20 volt power supply that was made years ago to drive the cross slide milling spindle motor. Control was via a Variac on the input side and a test meter ut in circuit to measure the current. A spot of 'alchemy' provided dyes - two greens from Dylon cold water dyes and two from disolving whole tubes of artists water colour into about 300mls each.
  The tank was filled with acid that was mixed several years ago as a pickle though never used. It appears very 'clean'. Having thought about it I'm sure I mixed this with clean rain water.
The cathode is a lead strip about 75mm wide and runs down the side, across the bottom and half way up the other side.
The hanging wires are from 1.5 mm ally welding wires bent back on itself and pushed a tight fit into a hole drilled into the test pieces (these were parted off from the stock the cylinder heads were made from - probably HE30 though not certain.
The first test piece was cleaned in cellulose thinner dried off then washed in the cold (room temperature) washing soda degreaser. 20 mins or so produce a rather striated effect which I put down to poor degreasing. It did however have a different 'feel' to it rubbing it across some wet and dry on a flat surface. It would not however take any colur. After ringing someone I knew who had some experience with anodising I was told to make sure the soda degreaser was hot and to increase the current and time to about 40 - 60 mins. His experiences weren't very encouraging regarding the colouring however as he had had a similar lack of take up. What he had been able to get to take albeit poor colour though had been acheived by an increase in amperage.
The second piece was left in for 50 mins and the current increased. This resulted in a much better part - a smooth and uniform nice grey finish. Dissappointment then to find despite an hour in the dye not so much as a speck of colour anywhere. I mixed up the violet dye as I have read that greens can be difficult but no luck there either.
These are the second (left) after treatment and the third part before
 I decide then to do as Bernie had suggested and use a 12volt battery to get a much higher current. Left in the same amount of time this did not come out any near as evenly coated as the second and as you can see left a deep pitted hole near the hanging wire.
Despite the much higher current this did not take up any dye either.
  The second part will not pass a current across the surface. The third will in areas - passing the test probe over the surface leads to intermittent connection.
My thoughts so far are that the current needs to be increased lightly more than the first set up can give. The time could be slightly longer perhaps. The biggest area for improvement has to be the connection between the hanging wires and the parts as I think that the area of contact is too small and probably reduces throughout the process.
I've bitten the bullet and ordered a decent supply unit which is something that's been needed for some time but always got by without.
I'm perplexed by the lack of dye take up at this time but quite impressed by the surface finish on the second piece. I will try inks next and wonder if solvent based dyes would work too
If anyone has any furth < |
| Ramon Wilson | 04/05/2010 12:30:36 |
1655 forum posts 617 photos | If anyone has any further thoughts to help overcome this problem then I'd be pleased to hear from them.
Hope this of interest - it's certainly taken my mind off machining for a while!
Regards for now - Ramon |
| Dave Martin | 04/05/2010 16:58:40 |
| 101 forum posts 11 photos | Ramon,
From a quick look/read here, areas I would definitely look at are (a) anodising electrolyte make up and control, (b) ano tank temperature control, (c) current density & control, (d) electrical contact, and (e) using proper dyes.
You may find it worth looking at some notes on anodising I posted elsewhere
Dyes - there are some who swear by clothing dyes and many more who swear at them! (especially their un-reliability) You will find a small investment in proper anodising dye takes a major unreliability away. You have to remember you're trying to get the dye molecules down into the honeycomb matrix - so if either (i) the matrix is too fine (ano'ed at too cool a tempeature) or (ii) you have dye moleules that are too big, you won't get much/any dye in there.
Dave Edited By Dave Martin on 04/05/2010 17:03:09 |
| Ramon Wilson | 04/05/2010 20:13:36 |
1655 forum posts 617 photos | Thanks for this Dave.
I have printed off your info and have read it through several times. I have several other articles some quite old but yours is much the best description so far.
Though I'm fairly happy with the 'cleanliness' of the electrolyte - I'm confident it is unadulterated, though it is not mixed with distilled water - it's obviously too weak - possibly 10 to 1 so this will be improved.
Temperature, well that was well down on your recommendation I guess - really cold outside and as you see this was carried out by the door with a fan blowing the fumes away. Would an aquarium heater be of use?
The PSU I have ordered has a current control facility up to 2.5A so given that I only intend to do relatively small parts I'm hoping this will be adequate.
I have a small piece of Ti sheet so will try to get a few strips out of it and make up some ally screws
The dyes? well as you say all I have read points to hit and miss using clothing dye. As I would like to make a good job of this I shall definitely get the right thing before the next attempt. I certainly won't have another go until I feel I have all the parameters in the right order!
A few questions-
What is in the 'de-smut' bath? and does this need to be at higher temperature than room temp?
I see you recommend washing/rinsing in DI water though other articles recommend washing under running water - presumably that's tap water. Is that likely to have a negative effect? The black container in the pic was filled with rain water the parts well swirled around in it to wash - again is that likely to spoil matters?
Finally would aeration from a small aquarium pump be suitable for agitating the acid?
Many thanks again and for those possibly expecting something a bit more positive in the results don't go far - "I'll be back"
 Regards - Ramon |
| Terryd | 04/05/2010 21:36:10 |
1946 forum posts 179 photos | Of course washing soda can defat but not as much as Caustic soda of course but I assume most users will at least adhere to the normal housewife's safety standards and wear rubber (in my case nitrile) gloves. But then again my gran used washing soda all her life for many purposes and still lived to a good old age. I'm not so sure she would have had the same luck using the caustic version so much  Terry |
| Terryd | 04/05/2010 21:52:01 |
1946 forum posts 179 photos | Hi Dave and Ramon, You are right about the dye problem, The only dye I have seen reported as working is one of the older Dylon types others do not work as far as I know. however the cost of 'proper' anodising dyes, inexpensive as they may seem, is prohibitive for very small scale or one off pieces. Here is a quote from this site:- "The only clothes dye that I have found that works is Dylon Multi-Purpose dye. Other Dylon brands do NOT work. I guess the dye particles are not small enough. Dyes that do not work include the Dylon COLD range and the dylon PURE COLOUR range." Probably those who swore at the dyes Dave, were using the wrong ones? So Ramon, it may be the type of dye you are using as well as the other factors suggested. The site above is well worth investigating even if it is a covered with annoying adverts, you can navigate around those  .I'm not sure if Dylon make these types of dye (Multi-Purpose) any more so it may be worth stocking up if you find a supply at the back of some old haberdashery store .Terry Edited By Terryd on 04/05/2010 22:19:53 |
| Versaboss | 04/05/2010 23:24:42 |
| 512 forum posts 77 photos | Hmm, it seems no one mentioned the fact that some aluminium alloys are 'not suitable for anodising'. I don't know what HE30 is and if it is ok or not, but know for certain that I can't use all the alloys my supplier has if the parts have to be anodised later. I suppose this means also that they can't be coloured. Checking the descriptions in my catalogue, I find the following alloys recommended for anodising: AlMgSi1, AlMgSi0,5 AlMgSiPb AlMgç,5Mn0,7
Unsuitable or bad are: AlCuMgPb AlCuBiPb For some alloys I see no recommendations. It seems the alloys with copper are the bad ones. I hope that this is of some help Greetings, Hansrudolf
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| Terryd | 05/05/2010 07:16:29 |
1946 forum posts 179 photos | Hi Ramon, I just noticed from your post that you used Dylon cold water dyes. These are the ones that apparently don't work. Here is a link which I posted before that may help, Best regards Terry |
| Terryd | 05/05/2010 07:22:55 |
1946 forum posts 179 photos | Hi again Ramon, Sorry about the multiple posts but you might like to look at the proper dyes available here for not too extortionate a price: Regards, Terry |
| Ramon Wilson | 05/05/2010 23:03:15 |
1655 forum posts 617 photos | Hi Terry thanks for these links. Had seen them before - have looked at so many on the subject and on dyes but have forgot to bookmark most (
 ) so this was a timely reminder.The power unit from Maplins has arrived and I have ordered some dye from the link above to see if that improves matters. If that doesn't work then I will try some of the Carswells stuff and if that doesn't work then It's going to remain 'au naturel' !!!.
At this rate it would have been cheaper to visit the guy up the road but then I suppose all I would have is two or three green bits to show for the outlay.
Managed to get my little old Burgess band saw to wend its way through this piece of Ti sheet tonight. Lain under the bench untouched for years it's about 2mm thick and isn't it bloody tough!
Hansrudolph- I have checked out HE30 - it appears this is a discontinued spec and it is now listed as '6082'. The anodising properties are given as good. I was aware that not all alloys will take hence test pieces cut off the stock the parts were made from but thank you for your thoughts on this.
It's a 'holiday' week this week so time is a bit limited - I keep sneaking in the workshop but not for long
 Regards for now - Ramon
|
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