Alternate Wash Solution


#42

So:

  1. hot soap water
  2. cold water
  3. IPA
  4. formwash with IPA

I don’t know about your time, but it sounds way too complex compared to DPM/TPM+rinse -> done


#43

@Multiscale: What do you do with the rinse water contaminated with resin?


#44

With the detergent water, the resin does not go into solution to the extent it would with IPA (and maybe not at all, I’m an engineer not a chemist). It settles out to the bottom of the ultrasonic cleaner tank and is left behind after the machine has been drained (assuming you have a unit with a drain). Just wipe out the excess resin with a paper towel and dispose of that as usual. The remaining rinse water goes in open aluminum foil trays set outside in the sun. Allow the sun to cure any remaining resin out and evaporate the water over time. This leaves behind a crust of cured resin which can be then disposed of in trash. Similar to the way you treat resin-contaminated IPA.

May sound more complex than just tossing parts into IPA or TPM but it’s not. Once you experience the joy of removing wet sphagetti supports, you will not go back to cold processing and having to clip off hardened supports.


#45

Just some days ago, I postet my experiences in a other threat:


#46

So I got samples of TPM and PS-100 from JR Hess and finally had time to compare. I printed 3D MON test pieces (three printed at the same time). After that I washed each one for 10 minutes, few minutes in one container and then transferred to next ‘clean’ container with the same solution. I did this for IPA, TPM, and PS-100. After that I left them to dry for about a day. TPM and PS-100 took way longer to dry. Maybe shop air can be used to speed up removal or a water wash like someone suggested.

After Form cure I have to say that results are pretty similar. TPM might have slightly smoother surface but not a lot. TPM has the least amount of odor and is not labelled as flammable. I think I am going to go this route just because of this. PS-100 is more expensive and smells more, it is also flammable but maybe not as bad as IPA.


#47

Did you dip the TPM samples in IPA afterward to rinse them off? Love to hear more about your workflow.


#48

I didn’t dip TPM sample in IPA. Basically swirl it around in first ‘rough wash’ container, then periodic agitation in second ‘finish wash’ container. Total of 10minutes. Then one day drying (I think I had to still blow some air at TPM sample afterwords). I am thinking about having two containers for rough and semi-finish wash and then Form Wash for final cleaning, all with TPM. I think that way the largest volume of TPA will stay clean for way longer.

Probably the biggest thing I learned is not to touch any surface until after cure. Another thing is that I am setting touch points as low as I can (0.10mm). It seems to support things ok and I can remove model from supports just by pulling on it. Basically just like in formlabs intro video.
Alex


#49

aokin,
Are you dealing directly with Hess or have they given you distributor, also, have they quoted you the various volumes available and costs. I am very interested in this solution and would greatly appreciate your inputs
TIA


#50

Anyone know a source for TPA in Canada? Is this the right stuff? https://www.sigmaaldrich.com/catalog/product/aldrich/302864?lang=en&region=CA


#51

I contacted the company directly. The minimum they sell is 5gal for $325. I am not sure if there are discounts for higher qty.
Alex


#52

I’ve just tried DPM again using a water bath as a rinse. It was obvious that the way water droplets were forming on the surface of the pieces that the water bath needs a wetting agent. So a good slug of washing up liquid in the water bath has helped the water drain off the prints and means they will dry without the need of an air blast.


#53

One alternative to IPA that works well is to use heated ultrasonic cleaner and some washing detergent - see videos on YouTube:

The price is very low (2 EUR per liter and below) and the liquids are easily available locally. The final results look better than IPA. I put all data into a single document with hyperlinksCleaning SLA printed resin.pdf (306.0 KB)


#54

uline.ca does not regularly stock TPA but after e-mailing them they appear to be willing to send it as a special order. All special orders are required to be $300 minimum.

They have a quote request form for this process.


#55

How do you dispose of the resin once it’s in the cleaner? Can you UV light it and have it harden in the cleaner?

Also I really cannot recommend the zortrax cleaner. It does not come with a cage, which is an absolute must and it’s over priced for what you get.


#56

Hi,
About Zortrax ultrasonic cleaner - it was shown on one of the videos but it’s too expensive for what we do. On Amazon there are hundreds of 40 KHz ultrasonic cleaners in the range 30 to 100 EUR which can do the job in our case.

My guess for disposing the resin from the cleaner - it should be done in the following way:

  1. Pour the liquid from the ultrasonic cleaner into wide tray and leave it under sunlight to polymerize the resin. What remains in the tray after sun exposure is detergent with polymerized resin (safe).
  2. Adding vinegar to the liquid will chemically react with the detergent and make it less harsh (most of them contain alkaline OH- groups) . The remaining liquid could or dry out on air (takes very long time) or to be disposed into drain (technically on this stage it’s not worse than dishwasher machine chemicals).
    Any other ideas for disposal are welcomed.

#57

Have you any reason to believe 40kHz is optimum or would 20kHz also be beneficial?


#58

Hi Dave,
Good point - in the article https://www.upcorp.com/blog/how-frequency-relates-to-ultrasonic-cleaning/ - they mention that higher frequencies penetrate smaller details and holes.

If you are wondering which frequency would work best for your cleaning application, there is an easy way to tell what is right. Generally, the lower frequencies in ultrasonic cleaning (20-25 kHz) are best for bigger parts. You can use these frequencies for cleaning large automotive materials. The lower frequencies tend to clean more aggressively, so larger parts can handle the action. For more sensitive and delicate cleaning applications, it is best to use higher frequencies. In the higher frequencies, the waves are able to penetrate through small holes and crevices more easily.

Another article is also pointing that higher frequencies can bring some benefits for fine details (like SLA)

So maybe 40 KHz is more beneficial in case of fine details SLA printed parts


#59

Have you tried putting to polymerise contaminated detergent ? does it form a gel or a precipitate?

Leaving contaminated IPA in sunlight produces a gel that is harder to dispose of than the original liquid.


#60

Hi Billb,
I didn’t try to put contaminated detergent under sun. But I can estimate what will happen - detergents are not dissolving the resin, they use low surface tension (like soaps) to remove the non cured liquid layer. When the contaminated liquid was left to rest - the resin will form a separate layer on the bottom of the tank. If there is a drain on the bottom of the tank, the resin could be removed, allowing the detergent to be reused (detergent is not dissolving the resin and hence remains unchanged).
If the contaminated liquid was placed under sunlight, I would expect the resin to form a relatively solid layer on the bottom (if the liquid was left to rest to separate the detergent from resin).
I’m switching from IPA to detergent so it will take few weeks before I can see what will happen with the contaminated detergent under sunlight. I’ll keep you in touch.


#61

One other hint - UV curing while immersing the parts in water. The claim is that the surface is less tacky and it’s harder. They explained the effect with water preventing the oxygen to come in contact with the resin surface.

The part can stay in small plastic bag filled with water while under UV light