Plastic Droplet Generation via Piezo

I came across this successful DIY printhead experiments documented on the wiki (http://reprap.org/wiki/Scratchbuilt_Piezo_Printhead), and I was wondering if anyone (in any industry) has successfully used piezo printhead to generate plastic droplets?

I know that Tektronix/Xerox's Phaser wax printers used a 'hot' piezo printhead to eject wax (I have one of them sitting around at home gathering dust) - it only gets up to 140C, insufficient for plastic jetting.

For you materials people out there, I have these questions:

* Is there any plastic that has a very low viscosity when molten (ie ~22cP)?
* Am I duplicating some well-known work by investigating this?

Why plastic jetting piezo?

I am interested in very high speed printing, and extrusion can only go so fast (inertial/acceleration limits of path-based FDM).

With plastic jetting, I can use a powder bed of ground plastic, and use the jetted plastic as a binder. With a wide carriage printhead, followed by a fuser pass, it should be possible to complete a layer of solid, no infill needed plastic in under 20 seconds (10s for jetting, 10s for fuser + new powder layer).

Or, am I duplicating HP's work?

HP's Inkjet 3D Printer

... plastics are composed from pretty long molecules, compared to water or wax, what's generating a sort of 'super-viscosity', that won't allow forming single droplets through high dynamic pulses

---

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

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

... reading through the HP-link, I'm seeing, they 'rebranded' the Inhibition-Sintering methode, where a dark powder is layed down, then separation lines are printed with salt-solution, the water drys, the salt forms a 'non-fusing coat' around the particles, and then a heater heats+fuses all powder-particles, not covered with salt to the solid beneath and to each other ...

---

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

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

Ok, understood.

Alternate concept: use SLA resin as the binder for powder bed, and cure with UV light.

The SLA resin has a very low visocity (lower then wax, IIRC) and should be able to be ejected via a piezo (maybe even thermal) printhead.

The trick will be make sure the actual printhead is well shielded during the UV curing pass, but colorants should be able to be added to the SLA resin for a full color print.