RE: [rp-ml] Stratasys models for investment casting

Sorry for getting complex on a simple question. . .

Polycarbonate is an amorphous material (as is ABS) and is usually used
in the "real world" as a 100% dense injected molded/machined plastic.
The FDM process typically "likes" amorphous materials. The SLS process
works much better with crystalline materials.

What does this mean? Well, SLS can process polycarb, but doesn't
typically get it close to 100% density. There is currently no real way
to get a standard polycarb part with the potential for optical clarity
in an RP process.

________________________________________________________

David K. Leigh | Rapid Prototyping and Production Services

Harvest Technologies | 1000 Industrial Park Rd. | Belton | TX | 76513

Phone: 254.933.1000 | Fax: 254.298.0125

www.harvest-tech.com | "Where Innovation Takes Shape"

-----Original Message-----
From: owner-rp-ml@rapid.lpt.fi [mailto:owner-rp-ml@rapid.lpt.fi] On
Behalf Of John Eric Voltin
Sent: Friday, February 08, 2008 10:01 AM
To: Timothy J Gornet
Cc: John Eric Voltin; Tracy L PWR Taylor; rp-ml@rapid.lpt.fi
Subject: RE: [rp-ml] Stratasys models for investment casting

I wasn't thinking of using polycarbonate for pattern making. I was
thinking in more general terms for prototyping, etc.

 - John

John Eric Voltin
Mechanical Engineer
Agile Technology
512-633-0394

> Why would you want to use a polycarbonate? For casting you would like
to
> have lower molecular weight materials (like wax) that burn out easier
and
> are less prone to shell cracking. Our local foundry runs Castform
> alongside their normal wax burnouts with no problems.
>
>
>
> Tim Gornet Manager, RP Operations
> email: tim.gornet@louisville.edu
> Rapid Prototyping Center
> Vogt Bldg. Rm 101, University of Louisville, Louisville, KY 40292
> Phone: (502)852-0714 FAX: (502)852-8890
> http://www.louisville.edu/speed/rpc/
>
>>>> "John Eric Voltin" <jevoltin@agile-technology.com> 2/7/2008 10:53
PM
>>>> >>>
> Are you thinking of Castform, which is mostly polystyrene prior to the
> addition of wax? I'm not familiar with any SLS material based upon
> polycarbonate, but such a material would be very useful.
>
> - John
>
> John Eric Voltin
> Mechanical Engineer
> Agile Technology
> 512-633-0394
>
>> While I don't think the ABS material would work well at all...Doesn't
>> Sratasys offer a polycarbonate material for the FDM process? I'm not
in
>> the casting business, but I know we used to do a lot of SLS patterns
out
>> of polycarbonate.
>>
>> Tracy Taylor
>> Pratt & Whitney Rocketdyne, Inc.
>>
Received on Fri Feb 08 20:24:28 2008