The Shop > Finishing
Parkerising technique
awemawson:
I can see the need for a 'Parkerising VAT' in the workshop. I would dearly like to Pakerise the fingers of the Edwards Box Pan Folder that I am currently re-building, but each one weighs about 15 kgs and there are 12 of them I think.
I visualise something like a tea urn with a built in thermostatically controlled heat source, suitable suspension points, and a lid to keep the vapours in. I see you mention using a stainless steel pan - maybe there is a stainless catering urn I could press into service. (It just so happens the postman has just delivered a catalogue from a catering supplier I've used in the past!)
PekkaNF:
Very nice write-up. Did you encounter any problems and how they were encountered?
I have experimented pretty much same way. I did read a lot and got really confused. There was really many different receipts with very many different ingredients and some claimed very different results from "same" methods.
I pretty much did the same than you with few differences:
I managed to source clean 85% phosphoric acid, therefore it was easier to calculate "exact" concentration, which actually does not seem to be very important, but it is nice to know for future use.
I also managed to source very nice manganese dioxide from a pottery supply store, turns out it is used for coloring pottery or something.
I used a cheap deep-frier, it had all the works I needed. Vat, thermostat, immersion heater. I used it as baine marie to bring it to a rolling boil and one vat of parkerizing solution was brough to 92C something....IR thermometer was not very reliable on these, but I found very cheap and good enough caramel thermometer from cookingware shop.
Looks like avoiding grease/dirt is the most fundamental thing....I even found very cheap clean uncoated/lubricated iron wire - it was sold to tie rebars together. Bundle of 0,7 mm 30 cm long precut wire cost few euros.
Tried liquid lawn fertilizer in different composition as preblack and it seemed to produce a bit more even results.
I have had hard time figuring out proper post rinse, water repellent (de-water) and oiling. Everything seem to work. Everything seems to be used. Worst idea was to use alcohol....needed instant oiling or developed some kind of rust right under your eyes.
I got best results with boiling hot distilled water rinse, followed by compressed air and then immersed into warm straight mineral oil and then let oil drip out until next day.
Pekka
Buksie:
Hi Guys
Yes I agree this is a usefull process, it makes my parts look a little better. One thing I forgot to mention, I found that if a part is case hardened it appears to be lighter in colour compared to the same part that was not hardened, anyone here with the same observation?
PeteW: I have not parkerized precision parts with close tolerances where measuring was required, I did however read on one of the many internet sources that Parkerising helps with oil retention and improves the wear life and bedding of the part, I have not put this to test yet, this will definately be a future experiment and something to try.
PekkaNF: You confirmed my observation that the recipe does not have to be followed by the letter, you mentioned that you use lawn fertiliser as a pre black, would you mind giving some more information on that process? Is it KNO3 based fertiliser?
awemawson: to me it sounds more like you want to construct a industrial setup, I think it is a good idea to use a thermostatically controlled vat to control the temperature, I am convinced you will get more consistent results if you can regulate the temperature of the mixture, that way you can time the process and get the same shade of black for diffirent parts, I think.
BR.
B.
awemawson:
--- Quote from: Buksie on September 03, 2013, 09:07:26 AM ---awemawson: to me it sounds more like you want to construct a industrial setup, I think it is a good idea to use a thermostatically controlled vat to control the temperature, I am convinced you will get more consistent results if you can regulate the temperature of the mixture, that way you can time the process and get the same shade of black for different parts, I think.
BR.
B.
--- End quote ---
:ddb: :ddb: Well if you're going to do it you may as well set yourself up properly :ddb: :ddb:
PekkaNF:
--- Quote from: Buksie on September 03, 2013, 09:07:26 AM ---.......
PekkaNF: You confirmed my observation that the recipe does not have to be followed by the letter, you mentioned that you use lawn fertiliser as a pre black, would you mind giving some more information on that process? Is it KNO3 based fertiliser?
--- End quote ---
I etched the part 10 mins of "preblack solution" that consist raw liquid fertilizer and 3% of phosphoric acid at room temperature (about 20C). Then hot water rinse of 10 minutes before dunking into park solution.
The fertilizer was NPK 13-1-3
Sorry the choice of languages
http://www.nelsongarden.fi/prod/Giva-Grass-GTI-25l_374331/Kasviravinteet-Giva_47979/FIN/SEK#
Burlap tells that the Nitrate is 4%, ammonium nitrate 3% and urea 6% plus 1% P and 3% K. This was pretty much the only form of nitrates I could get.
I made some notes of using also 3% HCL 11 min. It did react, but had no apparent effect on end result with tempering steel.
If anybody is interested my recipie for park is:
19,5g phosphoric acid ( 23g of 85% phosphoric acid)
1 litre Purified water
10g manganese dioxide, most of it does not dissolve
4 g of degreased wirewool
Cured classical way. Funny thing was that first 90C park did not produce very black, but next 92C experiment produced flocking mentioned often and made very nice jet black parts.
I am a bit middle of interior decoration of my garage (got grinding machine into garage just two hours ago...still on dollies) and some sundry things to make before I'll make some more tools that needs emergency bling.
Pictures:
Park with deep frier
Several end products, the one on the top with fertilizer pre-black
The preblack solutio with example, as you see I used sanding not sand blasting (I don't have sand blasting equipment).
Pekka
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