RE: QuickCast

From: Professor P M Dickens (pdickens@dmu.ac.uk)
Date: Wed Dec 02 1998 - 14:29:30 EET


Paul,
When I was at the University of Nottingham we were given the same
challenge.
We made some parts for Steve Throup at British Aerospace where we had a
thin wall of 2mm (0.080 inches). When we built the part we made sure that
we changed the default parameters so that we did not build with multiple
skins. We used a single skin. The other major factor was that we used
QuickCast version 2.0 with the hexagonal build style (as we were Beta
Testing it at the time). If you use previous versions with the rectangular
or triangular pattern you will have a very difficult time in draining.
Steve presented a paper on this at TCT 97.

We also built some test parts with different wall thicknesses and cast them
in steel. The thinnest wall was 1mm (0.040 inch) and we managed to drain
this very well (again using single skin and QC 2.0). With these thin walls
it is vitally important to use vents and drains. Without vents the
capillary action keeps the resin in place no matter how big the drain is.

Hope this helps.

Prof. Phill Dickens
De Montfort University
Leicester
England

-----Original Message-----
From: Paul Hanna [SMTP:phanna@CESSNA.TEXTRON.COM]
Sent: 01 December 1998 18:16
To: rp-ml
Subject: QuickCast

I am currently trying to produce a QuickCast pattern that has proven to be
a challenge. As a result, I have a few questions I wanted to pose to the
list. First a quick overview.

The geometry I am trying to produce is a thin walled (.060 in.) pattern.
 The walls are approximately 11.50 in. tall and are of a complex surface
design. With the wall geometry being this thin it has proven to be a
challenge to produce and drain. We have a SLA 5000 and are using SL5195
resin. I have been able to achieve a minimum wall thickness of .018 in.
per side leaving .024 in. for draining but have had little success in
draining the part. I have been working with the Stereolighography process
for quite some time but have not had the opportunity to produce any Quic
kCast parts until now. I am working with the 3D Systems FSE's testing the
boundaries of the QuickCast process. They have concurred that this is not
an easy part to produce. What a way to begin. Understanding the QuickCast
process such as I do regarding overcure issues, hatch type parameters,
laser beam technology, etc. we are presented with a couple of questions.

1. What is the smallest geometry thickness anyone has produced with
the QuickCast process?
2. Has anyone produced an actual casting from this thin of a pattern?
3. Is the best way to drain this part to use a centrifuge or is there
something else?

Any help with these questions would be appreciated.
Thank you.

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