Open Source Direct Metal Laser Sintering

[Sam Putman]

It's happening:

http://dev.forums.reprap.org/read.php?70,28272

Very early stages, but promising results.

This also has the potential to make sand into igneous rock. Obsidian
printing could be pretty amazing, no? With pure enough quartz sand and
the right technique, something with translucent/transparent
characteristics should be possible.

This is why our powder-bed needs to be planned around the concept of
an enclosure and quick-change toolhead. Just add laser and neutral
atmosphere! neutral atmosphere not needed for melting oxides.

-Sam

[Bryan Bishop]

---------- Forwarded message ----------
From: VDX <vdi...@web.de>
Date: Tue, Nov 24, 2009 at 3:30 PM
Subject: [RepLab] Re: Open Source Direct Metal Laser Sintering
To: RepLab Discussion List <rep...@googlegroups.com>



Hi Sam,

... thank you for the invitation - i'll read through and will post my
experiences here too ...

Like mentioned in the linked post i've already made some tests with
melting black rock-spheres of uniform size around 100 microns.

With my laser 2 Watts DC in a spot of 10 microns diameter was enough
to evaporate the spheres and make 'nanospheres' which aren't black any
more, but more of a translucent green.

When working with other lasers (e.g. pigtailed diodelasers) you have
to calculate the energy-density in the spot - i have another 1Watt-
diodelaser with spotsize around 60 microns but much worser coherency.
I think for the same efficiency like the Yterbium-fiberlaser at 2
Watts i'll need a 60Watts pigtailed diodelaser!

So if my calculations are correct, then with possible 50 Watts in a
spot of 10 microns i'll emit nearly the same energy-density with the
fiberlaser as with a diodelaser above 1 kW in a spot of 100 microns!

---
I think for fusing the spheres or dust to solid i'll have to adjust/
finetune the power/time ratio with PWM or with a modulator ... maybe
heating the powder-bed will be good too for reducing warping and
cracks in the solid ...

When the exhausting is working, i'll make some more experiments with
plastic-powders, sand and other materials.

For sintering metals i'll need inert gas, what's the next step
then ...

Viktor


--
- Bryan
http://heybryan.org/
1 512 203 0507

[Bryan Bishop]

---------- Forwarded message ----------
From: Marcin Jakubowski <joseph....@gmail.com>
Date: Tue, Nov 24, 2009 at 10:36 PM
Subject: [RepLab] Re: Open Source Direct Metal Laser Sintering

To: rep...@googlegroups.com


Friends,

Can we source suitable diode lasers of 1 watt for this purpose,
readily off-shelf?

Can you discuss the industry standards? What kind of power and spot
size do they need?

What are the limits to the effectiveness of laser sintering -
primarily access to powders? Are these powders economically feasible
to obtain?

It seems the laser can be done relatively easily. I question the
ability to get the proper quality control on powder at reasonable
cost.

Please shed some light on these issues.

Marcin

On Tue, Nov 24, 2009 at 5:21 PM, Sam Putman <atman...@gmail.com> wrote:

>
> On Tue, Nov 24, 2009 at 1:30 PM, VDX <vdi...@web.de> wrote:
> >
> > Hi Sam,
> >
> > ... thank you for the invitation - i'll read through and will post my
> > experiences here too ...
> >
> > Like mentioned in the linked post i've already made some tests with
> > melting black rock-spheres of uniform size around 100 microns.
> >
> > With my laser 2 Watts DC in a spot of 10 microns diameter was enough
> > to evaporate the spheres and make 'nanospheres' which aren't black any
> > more, but more of a translucent green.
> >
>

> Nice! Sounds like you have far more power than you need.
>
> Do you know anything about the fabrication of these tiny rock spheres?
> I know one can produce a finely divided metal powder through
> precipitation, although what to do with the waste eluent can be a
> puzzle.

>
> > When working with other lasers (e.g. pigtailed diodelasers) you have
> > to calculate the energy-density in the spot - i have another 1Watt-
> > diodelaser with spotsize around 60 microns but much worser coherency.
> > I think for the same efficiency like the Yterbium-fiberlaser at 2
> > Watts i'll need a 60Watts pigtailed diodelaser!
> >
>

> I know a diode laser is something that takes a clean room to build. Do
> you know anything about building Yterbium fiber lasers? What about
> blown glass for CO2 lasers?
>
> I know next to nothing about laser heads, and whether it's at all
> pragmatic to think in terms of designing a laser source that can be
> fabricated efficiently on a small scale.

>
> >
> > When the exhausting is working, i'll make some more experiments with
> > plastic-powders, sand and other materials.
> >
> > For sintering metals i'll need inert gas, what's the next step
> > then ...
> >
>

> Make sure your exhaust system won't leak oxygen, then:
>
> Take over the world!
>
> Or: Make finished metal parts out of powder, with a laser!
>
> For extra credit, figure out how to make nanometer-scale metal
> particles from scrap.
>
> cheers,
> -Sam.



--
--------------------------------------------------
Marcin Jakubowski, Ph.D.
Open Source Ecology
http://openfarmtech.org/weblog
http://www.replab.org
marcin at replap dot org
Skype: marcin_ose
--------------------------------------------------

Nobody said that building the world's first open source village would be easy.

-- Anonymous, 2009

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problem, pitch manure, program a computer, cook a tasty meal, fight
efficiently, die gallantly. Specialization is for insects.

-- Robert A. Heinlein

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