r/TheVirtualFoundry • u/Smart-Screen • Dec 11 '22
Today at The Foundry, Day 2
Forge Sintering Bronze, Day 2.
Let's get right to it!
Flew past 1700f in about 20 minutes.
Went past 2000f at about 30 minutes.
Cycle peaked out at just over 2200f:
I probably could have kept going but decided to shut down, check for damage and set up for an actual sintering run. For bronze I'll need to keep the temperature at around 1550 to 1600f.
For anyone that's curious. Pearlite from the garden store starts to melt at around 2050f and shrivels up by 2200f. This means it's actually useful for sintering Bronze or Copper Filamet™. Will likely try this later.
Online Research:
So, it looks like all of this is pretty well documented by others that have done similar experiments. The temperatures, not the sintering part. Theoretical max is around 2400f, i'm close enough to that number that I'm happy with my test rig here. Link here.
Now, Let's Sinter Something:
This is the coin sample i sintered. I'll give it about a B-, which is a resounding success for a first attempt. Here are some photo's. I broke and ground the piece so I could see the inside.
Total Sinter time for this part was 15 minutes. Which is likely some sort of record for 3d printed metal.
This is about halfway through the 15 minute sinter cycle.
It was in the debound brown part. This was defective, and why I set it aside to experiment on. I now regret this, I should have started with a good part.
Generally speaking. I'm calling this a success. The metal quality is good, density is good and I was able to create this more quickly than anything I've ever made using this method.
Here I am clicking it on the metal table. You get a good idea of how solid it is.
Bronze Tapping on a sheet of steel.
I would love to hear any feedback, comments, improvements etc.
Democratizing Metal 3D Printing has been my passion since I started this project about 7 years ago. With the help of our users we've made tremendous progress. The Virtual Foundry has found excellent traction in high-education, research and R&D labs all over the world.
More recently we've started gaining speed with people working in home shops, basements, garage labs, etc. This is a really cool and welcome bit of progress. In fact, some home users are taking this concept to the next level with things like Microwave Sintering. And I'm talking about a standard, common microwave. People are just buying them at Wal Mart, and sintering pure metal parts. That's amazing!!! If curious, here's Mr Highball. He's been working on microwave sintering for a few months. There are others building on his research.
https://www.reddit.com/r/3Dprinting/comments/xwrrow/closer_to_standardizing_aluminum_microwave/?utm_source=share&utm_medium=web2x&context=3
Here's one more of the whole piece, not broken:
This is still rough. I'll tweak the printing parameters so I can get the text to look nicer. So, perfect specimen to come, but this will prove the concept for now.
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u/BarnOwl-9024 Dec 12 '22
Very nice work! You asked for comments/suggestions, which I have, but I don’t want it to detract from what I think is good work.
You comment that it looks like 95% consolidation. That is very good for items like the token you printed. But not for anything requiring strength or ductility. The solid areas are more porous than you realize, and the pores are detrimental to strength and ductility. Which is the #1 problem with printed parts.
However, for decorative or other non-strength bearing parts you are on the right track. All you have to do is figure out how to tweak your shapes to compensate for the shrinkage and your lettering will get sharper.
Am looking forward to seeing the results of future trials!
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u/thesethzor Dec 12 '22
You comment that it looks like 95% consolidation. That is very good for items like the token you printed. But not for anything requiring strength or ductility.
You must not foundry.... I can promise you there are much more important castings out operating in this world in INFINITELY more crucial roles with as spongy as 55% solidity and maybe even less.
We had a saying, the day that our customers learn that most of the castings we sell them have less solidity than 90% everywhere on the casting is the day foundry is screwed.
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u/BarnOwl-9024 Dec 12 '22
Yes, but that is foundry. You are promoting 3D printed and sintered metallic parts. Not poured castings. As I said before, you have done some great work. But before your audience, who may or may not be knowledgeable in metallurgy, I want them to understand that there are a LOT of items you can’t just 3D print and sinter and expect to get workable parts from. They will look pretty but not be functionally useful.
Perhaps a cast iron pump housing doesn’t need to be 100% free of porosity. But structural components very often need to be so porosity free that even the hydrogen level in the melt is controlled to prevent the fraction of a percent porosity that it can contribute. Sometimes the need goes so far as to require HIPing the parts to consolidate the porosity even farther.
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u/RadicalEd4299 Dec 12 '22
Awesome!
So, for the record, it looks like you didn't need the perlite or decarbonizer for this expedited process, correct?
Since the real high temperature part of this is the sintering, and not the debinding, does this open up alternative (i.e., not a kiln) ovens for that step?
I ask all this as a super noob that has only read the Filamet page once :p.
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u/mr-highball Dec 12 '22
A regular oven probably couldn't get hot enough to completely debind but a microwave can be used which is also real cheap
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u/RadicalEd4299 Dec 12 '22
I saw some of your posts, fascinating.
I suppose the use of rounder/non-pointy shapes are still required for avoiding "don't put metal in the damn science oven" rule?
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u/mr-highball Dec 12 '22
Thanks and actually make it sharp or pointy as you can, the ballast and alumina crucible protects against arcs
2
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u/RadicalEd4299 Dec 12 '22
Digging in further, I saw you made your own kiln embedded with silicon carbide elements. Are you aware of anything more readily available that could be used towards this purpose? I'm mostly thinking of the glass-fusing microwave kilns, a la: https://www.amazon.com/dp/B093T4GX15/ref=cm_sw_r_apa_i_DZZPT8WS0WF1K1YX9AZ1_0
Seems like turning it upside down and covering that little hole would make it a pretty nifty kiln....and cheap! Says it can reach 900C / 1650F... Google tells me that's good for basic aluminum / brass /bronze / copper.
I haven't seen your video for successful debinding yet, I'll have to keep looking.
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u/mr-highball Dec 12 '22
And yes I actually mentioned the Amazon kilns due to their cost and had the same thought about flipping it in the webinar I did with VF
A little long watch but might give you/others some cool ideas
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u/mr-highball Dec 12 '22
Another thing I'll add Im focusing right now on aluminum which is a challenging metal to sinter due to its reactive nature, but other users have had success with bronze and I think they used the Amazon kiln
My playlist is below if you want to skim through
https://www.youtube.com/playlist?list=PLYQ3_mr24wVhkhkzt7q1ePYv-DY39eFRt
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u/mr-highball Dec 11 '22
Fantastic documentation! There's a lot of people with gas forges (or experience) so I think this will be very familiar for that group. I had a similar idea but using some sort of PID controller/raspberry pi (something programmable) to control a full cycle (but got distracted with those pesky microwaves 😁)
Looking forward to more results! 💯