RE: [rp-ml] Any Use for Glass-filled Nylon CAKE powder

A couple of comments on recycling glass filled nylon. I'm assuming that
you're talking either about EOS' or 3D Systems materials (Duraform GF).
If so, we've noticed several things about recycling GF. . .
 
* The remix requirements relegate the CAKE mix to a minimum. You can
use it, but we pitch the clumpy stuff.
* Surface finish on GF and PA are affected by poor powder quality.
* GF undergoes some strange issues when you have old powder. The GF
can actually become spongy with elongations approaching 20%. The
assumption here is that the heat from the glass may be affecting the
length of the nylon polymer chains, causing it to have better flex
properties and horrible tensile strength.
* Amount of glass content can vary - you can check densities of powder
to verify.
* There is a substance you can use to make the part cake better.
Virgin PA. :) Kinda expensive.
* Old Powder Usages - Christmas Nativity scene, Beach reclamation
projects, dumpster filler. . . You can even make little gnome molds and
use the molten powder to create the little garden features for your
whole neighborhood.
 
To be honest, I'm a big fan of white CAKE mix.
*********************************************
David K. Leigh (254)933-1000
Harvest Technologies fax(254)298-0125
Rapid Prototyping Services dkleigh@harvest-tech.com
-----Original Message-----
From: Ross Nicholls [mailto:Ross@mnl.co.uk]
Sent: Friday, February 24, 2006 6:14 AM
To: rp-ml@rapid.lpt.fi
Subject: [rp-ml] Any Use for Glass-filled Nylon CAKE powder

Hello All
 
It has been a long time since I posed a question on this list, but I
still keep an eye out for interesting discussions.
 
We are using a HiQ Sinterstation with a variety of 3D Systems powders.
As with all bureaux we try to push the boundaries of the recommended
parameters for building/recycling etc. etc.
 
When we push the recycling boundaries for standard nylon (i.e. less
virgin, more cake and overflow) we get a drop-off in surface finish
quality, but not a lot else in difference. This is acceptable in certain
conditions, especially when painting parts etc.
However when we do the same for Glass-filled nylon (noticeably
introducing CAKE into the mix) we get a distinct drop-off in strength of
component. (No noticeable down-turn in surface quality)
 
GF questions
Does anyone else agree with these findings?
Does anyone else use CAKE in their GF recycling?
Are there any additives we can introduce to increase the strength, when
using CAKE in the mix?
 
Am I wasting my time trying to use the CAKE at all, should I just bin
it?
 
 
Thank you
 
Ross Nicholls
 
General Manager
Malcolm Nicholls Limited
 
Waterloo Industrial Estate
Bidford-on-Avon
Warwickshire
B50 4JH
 
T +44 (0) 1789 490382
F +44 (0) 1789 490130
E ross@mnl.co.uk
W www.mnl.co.uk
 
Received on Fri Feb 24 14:52:00 2006