Remove wax from hot water or mineral oil. 3D Printer support material removal. 2

[VeryFungi]

Hi all,

I have purchased a 3D Systems ProJet 3500HD Max. After a very long ordeal I am finally making parts. I am trying to speed up and streamline the cleaning process. The short question is what is the easiest way to remove wax from 70c water in a continuous operation. In other words I do not want to cool the water to remove the wax. This is a very small operation.

I can make about 75 parts at a time, and they are about 1" x 1" x .5". The parts are UV cured acrylic and are completely encased in wax when they come off the printer. The parts can not withstand higher temperatures then 70c. The wax melts around 60c.

Here is the longer version. The parts come out of the oven 70c with a fair amount of wax remaining. The current process is to remove the parts one at a time and pat them down with a paper towel to soak up the wax. It doesn't get much before the wax cools.

Step two is a quick soak in heated 70c mineral oil, either in an ultrasonic cleaner, or a crock-pot. I have been able to sift off the top remaining wax on top of the cooled oil, but it is messy, I lose oil, and it doesn't get it all. I have tried a water based EZ-Rinse, but it get's saturated fast and the wax doesn't congeal very well on top of it. It's probably expensive.

The next step is to wash the parts in hot soapy water, I have to throw the water outside due to the oil in the water.

So far my only successes have been dying the parts black with RIT dye. A full container in about a gallon of water. This works very well, but any oil and wax left over saturates the top of the water inside the dying pot. Just pull the parts out of the dye through the junk you are trying to get rid of and it creates a thin film on the parts. Cleaning by hand can help remove some of this.

The final step is to seal the parts. I have so far not been able to get standard spray can paint or primer to cure properly. I'm assuming I have not removed the wax completely. I have considered a week sodium hydroxide wash, but am not crazy about it. I have had some success with painting with polyurethane. For now I'm doing it by hand by thinning water based Varathane 50% and brushing it on. I plan to spray it on eventually.

So I would like to replace all of this time consuming part by part handling. I would like to replace all of these steps excluding sealing with one operation. If the parts can be put inside a 70c water bath, but with circulation and filtering to remove the wax I think I could seal them directly.

I'm an Electronics Engineer so this is all alien to me. lol Please help me!

 

[VeryFungi]

I will try to add pictures...

The parts in the printer.

Parts are encased in wax.

Here are the small parts.

The parts go into an oven to remove the bulk of the wax.

The dying bath, 5 minutes at 70c. The bath is about half gallon water and a full bottle of RIT dye.

After dying the first batch there is wax floating on the surface. It is impossible to remove the parts without the wax transferring to the surface of the parts. I have tried to skim it off with a paper towel, but it is very wasteful.

You can see the wax on the parts. Anything that is not flat black is wax.

The poly works because it uses oxygen to cure, I guess? But spray paint will not cure.

The finished product, but way too difficult...

Any way to filter the wax from the dye bath? Remove wax and dye in one process? Help.

 

[VeryFungi]

I will try to add pictures...

The parts in the printer.

Parts are encased in wax.

Here are the small parts.

The parts go into an oven to remove the bulk of the wax.

The dying bath, 5 minutes at 70c. The bath is about half gallon water and a full bottle of RIT dye.

After dying the first batch there is wax floating on the surface. It is impossible to remove the parts without the wax transferring to the surface of the parts. I have tried to skim it off with a paper towel, but it is very wasteful.

You can see the wax on the parts. Anything that is not flat black is wax.

The poly works because it uses oxygen to cure, I guess? But spray paint will not cure.

The finished product, but way too difficult...

Any way to filter the wax from the dye bath? Remove wax and dye in one process? Help.

 

[VeryFungi]

Or maybe just tell me a more appropriate forum, or a place where I might find some information. Filtering wax from 70c mineral oil preferably, or water... Seams this should be within the realm of possibility for the small operation I am attempting. Anything at all?

 

[thorium1]

Im pretty sure when people talk about chemical engineering, they are talking about a large scale production plant with reactors, pumps, compressors, columns, towers etc. Not really about more effective ways to remove wax from 3D printer models. (FYI, I like your 3D printer!!! Its so cool!!!)

Perhaps an enthusiast website or forum about 3D printer technology? Im sorry, but I dont know of any though, but I not sure many people here would have the expertise to answer your query.

 

[zelgar]

Here's a few ideas, but I don't know if they'll help or work :
[ul]
[li]Try using a hair dryer or heat gun after taking the parts out of the oven to keep the temperature up when trying to remove the wax[/li]
[li]Try putting the parts in hot water soapy and use a toothbrush (might be messy &/or costly) to help remove wax[/li]
[li]Try putting the parts in cold water and peel off as much wax, repeat hot soapy water & cold to maximize wax removal[/li][/ul]

 

[VeryFungi]

This is a chemical based problem. Can you even filter wax from mineral oil, also called paraffin oil... Anyone out there with chemical engineering knowledge able to point me to a better place to ask my questions?

 

[zelgar]

Solvents and degreasers can remove wax. Some of them will attack plastics and many can produce toxic fumes. If you have any of the orange degreasers at home, try a little using a toothbrush to help apply/scrub the parts.

 

[bimr]

From your discussion, the issue seems to be that you are forming a paraffin emulsion in the water that is difficult to remove. Paraffins form very stable emulsion and are used for many industrial uses such as wax for that purpose.

To remove the paraffin from water, you need to "break" the emulsion. This is commonly accomplished by adding alum and lowering the pH to about 5.3.

Alum is a common chemical and widely available. Suggest you obtain some alum and experiment with it.

http://www.google.com/url?sa=t&rct=...loHIAg&usg=AFQjCNFO5QWqVJmbT-G3ailxtoRslF3WsA

 

[VeryFungi]

Thank you all for your replies! Many replies are suggesting tedious hand work which is what I want to avoid. It would be fine for a small number of parts, but what happens when I print 75? Also just getting the wax off the parts is not the issue, I can certainly do it, but I need to find a more economical method. I need to be able to get the wax off in bulk batches. The mineral oil does the bulk of the work, so I think the place to concentrate the work is there. It's possible the film in the dye bath is mineral oil and not wax at all.

Here is the 70c mineral oil bath after only a small number of parts. Again what happens when I do 75 parts. I can't justify throwing it out every parts cleaning so I need to filter the wax from the mineral oil.

 

[btrueblood]

You need to deposit fresh, clean solvent onto the parts to rinse away the wax. So, either a series of tanks with solvent, into which you dip the parts in sucession, so the dirty parts go in the dirtiest solvent and vice versa, or a spray rinse of the solvent, or a vapor degreasing cycle. All of which supposes that you can find a solvent that dissolves the wax and not your parts (I presume those are some kind of ABS?).

I don't think any water-based cleaners are going to cut thru wax to clean your parts. Oil yes, but wax is tough. ABS "should" be fairly resistant to pure straight-chain paraffins (I'm using the chemical definition of paraffin here), so find a very short chain paraffin, like hexane or heptane. You might need to find a good chemistry supply house to find those. Avoid polar solvents like ketones, or aromatics (benzene, gasoline), as those do attack ABS.

Seperating mineral oil (which is a paraffin, mostly) and/or the solvent mentioned above (which is a paraffin) and paraffin wax (which is a longer-chain paraffin) can only be done by fractional distillation or freeze distillation; the latter is sort of what you are doing now. Chill the fluid way down to maximize the fraction of wax that freezes out, then pour the liquid through a coffee filter to strain out the solidified wax.

"I have to throw the water outside due to the oil in the water." Please don't do that. I may eat a fish someday that had to swim through your oily detritus. Recycle the oil/solvent/wax, or burn it, or filter the water, but don't just dump it on the ground.

 

[moltenmetal]

You can freeze the wax out of the water easily enough. Move the part through successive baths of hot water, then allow the water to cool after all 75 parts have been through all the baths. I don't understand your aversion to allowing the water to cool. Just don't dump the hot waxy water down the drain or you're looking at a costly drain unclogging later.

Consider adding dishwashing detergent to one of the later 70 degree water baths. Or to all of them except the first and last ones which will be a water rinse. The 1st one will just melt off most of the wax, leaving it easier to recover- though why you'd bother is beyond me. The soap will help remove the wax, and more importantly to keep it off the parts once it's been removed. It will make removal of the paraffin from the water impossible, but again- who cares?

Your final wash in warm paraffin oil should remove only the last traces of wax, and should therefore last a long time. Want it to last even longer? Use it in a series of baths too. Each time you do another set of parts, discard the FIRST bath only, move all the others up one step toward the front of the line, and pour fresh clean oil into the last bath. Voila, you have something close to a countercurrent washing operation, making efficient use of your solvent.

Another approach? Go to Harbour Freight and buy a solvent degreaser- comes with a pump and all for about $50- used to degrease car parts. Use something like Varsol, deodorized kerosene, alkyd paint thinner, Stoddard solvent etc.- basically parrafin oil, except shorter molecules- less viscous, better solvent. None of these should harm acrylic resin once cured, though they may cause it to craze crack if you use the solvent too hot. The wax should come off even without warming the solvent much. Discard solvent when finished. Warning: don't warm the solvent beyond its flash point, which for these materials is around 100-120 F.

Removing wax from paraffin oil is possible, by adding solvents, cooling to precip the wax, then distilling to recover solvent. This is obviously not easy enough to justify the cost versus just chucking the paraffin oil when it becomes waxy. Same with the You can buy non-USP grade paraffin oil in 5 gallon pails for very little money.

Yes, chemical engineers DO get involved in optimizing processes like this, so you're in the right place! And hey, everybody needs a hobby- I have many personally, one of which is making parts a little less fussy than yours but a whole lot more durable- by sand casting bronzes and aluminum.

 

[VeryFungi]

Hi MoltenMetal,

Sorry for the confusion I had a lot to put out there and it got a little mushy. When referring to hot water I was thinking of a way to dye and clean at the same time. So a method that could filter hot wax from water but admittedly I sort of left out too many details.

I believe after review of these replies probably the best solution would be to go with 5 gallon buckets, and discard after saturated. I saw 5 gallon buckets for $56.00 have no idea on the shipping. Have no idea how to find it locally.

The parts are acrylic and one issue is the temp can not go above 70c. The wax melts at around 60c so it melts slowly. Whatever I do the parts should never exceed 70c. This is well above the flash point of the solvents so that's out.

I don't know if hot water will remove the wax.

My biggest problem is printing the parts is very expensive which limits the amount of experimentation I can do. It's not just the process but I need to think the process through, build fixtures, trays, spill pans and the like. How to move the parts, how to skim, filter and drain the oil. I am so out of my comfort zone here.

 

[VeryFungi]

Is there any way to edit messages?

I meant I don't know if hot water (alone) will remove the wax.

 

[btrueblood]

"Whatever I do the parts should never exceed 70c. This is well above the flash point of the solvents so that's out."

I think you are mis-reading what molten and I have said. We are saying use the solvent at room temperature to dissolve and rinse away the wax from the parts. Then detergent wash the parts to remove the residual solvent.

 

[VeryFungi]

Oh I see, sorry.

Can you guys chime in on the possible uses of Sodium hydroxide water mix in this application?

 

[moltenmetal]

Sodium hydroxide will be useless- this is paraffin wax, not alkali-soluble animal fat.

Warm solvent will dissolve the wax. It need not be hot, but dissolution at room temp will probably be slow.

Talk to a fuels or lubricants supplier for the 5 gallon pails of mineral oil. But I'd go with Varsol in a parts washer personally- it's meant for this job. Follow up with a dunk in fresh clean solvent, then warm soapy water, then rinse with lots of water. Should help you get more even dyeing.

 

[VeryFungi]

Thanks for the info, it saved me a lot of wasted time. I have received my work benches, so I can start putting the cleaning station together. By posting here I received a lot of useful information. Although I'm not exactly sure what I will end up doing yet. lol

 

[VeryFungi]

Can anyone shed some light on the practicality of using a 90% alcohol soak prior to painting? 3D Systems has asked me to try this...

 

[btrueblood]

You can certainly try. Alcohols won't dissolve the wax, but might help get rid of detergent residues and/or any polar solvents you may have used.