We continue with our quest to experiment with a wide variety of materials for 3DP. Our previous material was presented in:

Bone Yard

In our Advanced RP/RM (rapid prototyping/rapid manufacturing) course, I was discussing the course requirements. One our of requirements is an independent research project and report to be undertaken in teams of two (the project is worth 40% of your grade). As an instructor, I would ask the class at every meeting if they had any ideas for a project.

One of the teams (composed of Adele Klee and Zack Chan) approached me after class.

Can we talk about our project?

What do you think about printing in Chalk?

What?” “Why?

Brains go into overdrive: “Talking to the teacher when I felt like one of the only ones in the class who didn’t really know what was going on was terrifying.  I’m not in the major and I suppose I was worried that that would be held against me.  I asked about the chalk.  It never actually seemed like that great of an idea, but it was mine and I had to have something.  I noticed what seemed like disapproval and panicked.  My mind was racing.  I had to think of something, anything, that’s white and powdery.  It shouldn’t be that hard, only two criteria.  Find something white- check.  Find something powdery- check.”

In a moment of panic:

What about salt?“  “Do you think it will work?

Sure, maybe!

How do we get started?

You’ll need to get the salt in the correct powder size.

Get a coffee grinder and start grinding the salt to something super fine!

Then do a simple powder distribution by running the powder through 60, 100 and 120 screens.

This process took place across several weeks. Once they got the salt to something that looked like white dust.  They screened the batch through 150 mesh screen.

On to bench testing — to determine how the new powder liked our binders and if not, then test out various additives.  Over the next two weeks  different sets of adhesives and  ratios were tested against our existing binders. Success!!!

They loaded up the 3D printer with  the salt mixture and used an existing binder solution. Let’s just say their first 3D printing tests quite successful.  The salt powder mix spread extremely well, and produced the best surface finish on the printing-bed surface that we have ever seen.   Several adjustments to layer thickness and saturation settings, and amazing parts appeared.

“It was so sudden, absolutely no planning whatsoever, and he liked it!  It was so exciting that I, a random, non-mechanical engineering student, would come up with an idea that was good.  We ran with it and got amazing results.”

Did we mention that it costs something on the order of $4 for 25 lbs of Salt!

Final Recipe:

Finely Powdered Salt  — 8 parts by weight

Maltodextrin                  — 1 part by weight

It is so much fun to watch the process happen again.

{We’re not sure if this is really a first as we’ve heard some rumors that UCLA Architecture Department might have tried salt printing 10+ years ago.  It doesn’t take away the excitement of seeing some of the amazing quality parts being printed.}

Creative Commons License
Salt Printing by Adele Klee, Zachary R. Chan is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

{additional references have come forward today, please see}

* Yoji Marutani; Takayuki Kamitani; Masuyoshi Tomita,  (12/01/2004). “Manufacturing sacrificial patterns for casting by salt powder lamination”. Rapid prototyping journal (1355-2546), 10 (5), p. 281.

* Yoji Marutani; Takayuki Kamitani; Masuyoshi Tomita (2005). “Selection of binder materials for salt powder lamination”. Materials science forum (0255-5476), 475-479, p. 2909.

 

21 Comments on Salty Parts – 3DP in Salt

  1. Cassidy says:

    Great job! What binder did you find worked best? Please say it was rice wine (simply for ease of purchase and cost). What type of grinder did you use (ex. type/brand of coffee grinder).

  2. admin says:

    Cassidy, The students used XF but RW should be fine. You will need to run tests to get the saturation settings correct.

  3. bre says:

    Congrats on the great jump forward. Awesome!!!!

    I have to ask, why the non-commercial license? That makes it so that folks can’t use this commercially to do things like making things and selling them. That’s a pretty restrictive license for such an awesome technology!

  4. admin says:

    Bre, that’s a great question. I pointed the students to the CC website. I told them to read the information and choose the most appropriate license form. I will forward your response to the Salt Team and report.

  5. admin says:

    Bre, I forwarded your response to Zack and Adele and they issued a new CC license. Thanks for your inquiry.

  6. Paul Dutch says:

    Great work..
    Do you think that your Salt Mixture might be useful as a support material in Additive Manufacturing? Does the printed material still dissolve in water?

    Paul

  7. Zack says:

    Paul

    Yes that is one of our thoughts exactly, it should dissolve in water there is no chemical reaction that fixes the form it is fixed from recrystallization, however I have not tested this yet I do not know if the dissolving is as aggressive as the sugar sugar powder

    Thank you for your interest

    Zack

  8. UMN_Design says:

    Has any progress been reported on the salt printing front? We’re investigating sources for salt that is ready out of the bag. It looks like one of these might be appropriate:
    Cargill Microsized® 86 Fine Salt (industrial)- >98% thru USS 200
    Cargill Alberger® Shur-Flo® Fine Flour Salt – screning 70-200
    Cargill Microsized® 95 Extra Fine Salt (food grade)

    Here is a salt comparison that contains some screen mesh information.
    http://www.saltservice.com/lea.....-sheet.pdf

    Can anybody make a recommendation of which of the above products may be most suitable/likely to succeed?

    Thanks
    -kevin
    UMN_Design

  9. admin says:

    Kevin, good luck and keep us posted. I would guess CM86 should work. Send pictures and we’ll post them.

  10. UMN_Design says:

    FAIL – We tried salt prints with Cargill Alberger® Shur-Flo® Fine Flour Salt (screening 70-200). After many attempts (including screening the salt to a finer size) We simply couldn’t get the machine to lay out additive layers without dragging the previous layers across the build bed. The Shur-Flo salt is courser than expected, so when we get a chance we’re going to try to source a finer salt to see if it “packs in” the build bed more firmly…

  11. admin says:

    All really successful powder needs to be in the 20-100 micron size range (check the original papers by Sachs & Cima) that means it needs to be screened at 200 mesh but 300 mesh would be better. We used a coffee grinder to make the particles smaller.

  12. kyle says:

    hmmm. I wonder if when grinding, you actually produce a range of particle size. the reason i mention this is because this is exactly what you intentionally make in the sugar-sugar recipe. and having the right ratio of particle size seems important in that recipe. too much course material and it ‘drags’ as UNMD describes, too much fine material spreading’s difficult and resolution is poor.

  13. admin says:

    Kyle, we asked Zach about particle size in the salt printing. His response — some of those details were in the our report. We will attempt to get Zach to release their report.

  14. It would be wonderful to read their report! Have they tried mixing fillers into the salt to improve the strength of the final product? Off the top of my head, it seems like 5–10% of montmorillonite might improve the strength substantially, if you can get the salt to bind to it. (Other aggregates like fine silica sand or asbestos might work as well or better, but those bring up some serious safety problems.)

    I assume “XF” is XF1?

  15. Zack says:

    Here is a link to the report.

    http://students.washington.edu.....inting.pdf

    Thanks,

    Zack

  16. Ali Shah says:

    Morton salt has a variety of products that will work for thisapplication. They have a broad distribution of sizes and salt particle shapes. Check it out!

  17. Buddy Smith says:

    Is this report mirrored somewhere? The link above is gone.

  18. ganter says:

    Buddy, we fixed the link. Thanks for pointing it out.

  19. Dixit C.G. says:

    Hi,

    I am Dixit from India. I will be buying Z 450 shortly. I was looking for alternate materials for Visijet PXL Core. I find this site very interesting. It is giving me all kinds of solutions I was looking for.

    Which are the powder form adhesives can be used with Paster of Paris?

  20. murray says:

    What type of strength did you achieve ? could you use a resin polymer binder to significantly increase the strength ?

  21. ganter says:

    We just did preliminary strength testing by breaking the test bars. Yes, you could infiltrate with any variety of polymers which would increase the strength substantially.

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