Printing a cast-forming material with a peizo inkjet printer?

Ok, so some print heads for inkjet printers us peizoelectric pumps, and get resolution and accuracy in the micron range. If we can use them to print in a material that can stand high temperatures then they could make casts, a highly useful application.

Perhaps if a material could be found which was carried in a solvent? The droplet hits the surface in the solvent, which then evaporates, leaving a deposit.

Ideas on what material/solvent combos might work?

Forget the solvent. You won't find anything that has a low enough viscosity, quick drying time, etc. One likely candidate would be to use wax-based inks. I believe Dye Sublimation printers use these. I could be wrong.

I maintain a wax printer by solidscape.
These printer indeed use wax, Two types of wax. the jets are not really like inktjet printers. They use only one hole while inktjets use many (correct me if i'm wrong). The jets use piezo electric power to eject the wax.

Printing materials

The printer uses two types of wax build (green) and support (purple/pink). Both have different melting points (forgotten the exact temps so these are estimimates). Build is about 190 and support about 130 degrees celcius.

After printing
To remove the support wax a really expensive liquid is used. After some research it was just cheap kerosene . This is heated to somewhere between the melting points (145 degrees).


Heating wax print system
In the printer most things are heated. The aluminum wax tanks, the pfte transport lines, the jets. The tanks are pressurized by pumps.

maintianing layer hight
This part is really different from reprap printers. While the Z stage moves down while printing, the wax printing process is not acurate enough for the layer height. The printed layers are too thick (2 or 3 times too thick). After the wax has layer has been cooled 20 to 70 seconds the layer is milled to the exact layer hight.

here a vid of the printer in action:
[www.youtube.com]

Feel free to ask questions about wax printing.

... you should read here - [forums.reprap.org] - and through other threads tagged with 'selective inhibition sintering' - [forums.reprap.org]

With this methode you can use a simple ink-jet, printing with a salt solution as ink and an IR-heater for selective melting the topmost surface.

Another methode will use lasers for selective melting the powder surface - you can find some old threads about this too ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

??? how are any of these things printing in a cast material? The wax I can see and that is a good one, you could make a wax object and then do lost wax casting.


But I'm talking about printing the cast directly. I know there are many other methods, but at some point you gotta pick something and look a little deeper, instead of always jumping from one option to another.

I looked up some salts, sodium chloride melts at 809 dec c, so it's not enough for steel but could work for lower melting point alloys. There is an allow made of zinc and aluminum that is as strong as cast iron but melts at only a couple hundred C which is commonly used for parts in cars. (heard about that from the multimachine project). That could be a winner. Still,not as good as steel.

I don't know how much of an issue the viscosity is. I may try to look it up in a second, however the peizo printers use water based inks so they don't require anything super low viscosity or anything.

Well the obvious place to start is to identify which print heads use peizo and obtain such a printer, and start experimenting with salts in water as inks. That will help to clear up issues regarding if the solvent swells the underlying previously printed material etc (doesn't seem likely with salts though?).

I have read some Epson printers do but do not recall the model numbers. It may require some hacking to persuade it to print at a reasonable rate but that can be left for now and we can simply move on to proof of concept re:printing temperature resistant materials at high res in 3d with low cost equipment.

One reason to use inkjets like this is their ready availability and high resolution. They may be very slow, but that will have to be checked with experimenting unless someone can find the droplet sizes and droplets per second, or flow rates or something. I have a microcscope here to to do inspection of the results, handily.

... in the SIS printing process you can use any powdered material that you can melt with an IR-heater.

When you push a thin layer of lets say black ceramic dust on a solid surface, print some thin lines in this surface with salt and then heat the surface with a Halogen lamp to maybe 1500°C, then the particles covered with salt won't fuse, so only the not printed area will melt and fuse together and with the surface.

When repeating this several times, you'll receive a block of ceramic, embedding solid objects, separated by printed/salted perimeters and dividing planes.

This could be any 3D-object or casting form, that can withstand more than 1000°C - or the specific melting temperature of the solidified material ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Hm, that might be a good option, but radiant heating cannot achieve possibly a higher temperature than the radiant element, and indeed will necessarily achieve much less. I know sls machines can do copper which melts at 1086 deg c though (or maybe it was a copper alloy that melts at lower temps...) ... What sort of resolution and accuracy do you get with sls? Do you get full density parts?

I wonder what radiant heating element they use. Tungsten halogen lamps have a filament temp in the range of 3500 deg v so they could achieve higher temps than nichrome, which iirc was what was used in the sls machine I read about. (nichrome melts at 1400 deg c).

I am not able to find that doc on the SLS printer. There was a pdf describing in some detail an SLS prototype printer. Anyone have it? Can anyone find it?

looking at [reprap.org] there are a few sls printers, I think none of them are actively developped or reproduced. there might be a source of inspiration for your own project there (perhaps collaboration)
[reprap.org] talks about the laser and energy consumtion on materials that require lots of power to melt.

oops I meant SIS, selective inhibition sintering, not SLS, selective laser sintering.

... you can 'concentrate' the heat of an aerial heater on a smaller surface by optical mirrors around the heater.

I've salvaged a stylish bread toaster, where the heaters weren't NiCr-wires wound in a plane, but two glass-rods with embedded wire-coils, maybe 10mm in diameter and 200mm in length.

For heating the complete surface of the toasts this rods were placed in a faceted mirror, so the IR-light was averaged over the target area.

With a different mirror-arrangement (see the ellyptical mirror-tubes in pulsed NdYAG-lasers) you can focus as much of the IR as possible with the optical setup on a line in front of the heater rod, so it should be easy to heat the surface under the focus-line above 1000°C by slow moving the mirror with the heater along the surface of the print ...

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]