RE: [rp-ml] SLS - How much material can be recycled?

From: EXT-Taylor, Tracy L (
Date: Tue Sep 06 2005 - 22:51:04 EEST


While I agree that the new powder feed systems are, as you stated,
"effortless and accurate"...How well do they work in practice. Since I
have no experience with such a feeder there is one big question in my

If the powder added into the recycle hopper isn't close to or the same
as what is already there... OR If the powder in the recycle hopper isn't
homogeneous...Wouldn't your powder blend ratio need to change during
your build to give you a consistent end result?

We blend in batches to make sure the powder is consistent. Just curious
how you achieve that with a continuous feed system.

Tracy Taylor
Pratt & Whitney Rocketdyne, Inc.

-----Original Message-----
From: Shane Collins []
Sent: Friday, September 02, 2005 1:32 PM
Subject: RE: [rp-ml] SLS - How much material can be recycled?

Dear Ricardo,
EOS has a new PA-12 based laser sintering powder designed specifically
for increased recycling. The new powder called PrimePart(TM) is now
available. As David points out, processing parameters effect powder
performance, but the use of a modern powder feed system makes the mixing
procedure effortless and accurate. Shane

Shane Collins
Regional Manager
EOS of North America, Inc.
805 427 0019

-----Original Message-----
From: [] On
Behalf Of David K. Leigh
Sent: Thursday, September 01, 2005 1:51 PM
Subject: RE: [rp-ml] SLS - How much material can be recycled?

There are several things that go into the recycling of the material:
base material, machine operating parameters, mix ratio, and mixing

Philosophy: Do you mix in new or run to extinction. You will have more
consistent results if you blend virgin powder with used.

Base Material: EOS PA requires more virgin than 3D Duraform. GF
requires more than PA. etc.

Machine Settings: The hotter you run the build, the more the powder
degrades and the more virgin you need to mix into it.

Mix Ratio: Virgin material is added to used material in a ratio range
of 30-60% depending on the above. You basically have to figure out what
works for you and your tolerance for "orange-peel" and be consistent.
It's as much art as science early on until you get used to it.

Actual tensile properties don't suffer greatly. It's more cosmetic and
tolerance specs taht are effected.

David K. Leigh (254)933-1000
Harvest Technologies fax(254)298-0125
Rapid Prototyping Services

-----Original Message-----
From: Raffaele Martinoni []
Sent: Thursday, September 01, 2005 1:08 PM
Subject: R: [rp-ml] SLS - How much material can be recycled?


the problem by recycling is mostly orange peel. OUsed material could
improve properties like elongation.

>---- Messaggio originale ----
>Oggetto: R: [rp-ml] SLS - How much material can be recycled?
>Data: Wed, 31 Aug 2005 16:26:49 -0300 (ART)
>>Dear list,
>>Regarding the SLS process, does anyone have experience on material
>recycling? How much material can be recycled without implicating
>the mechanical properties of the parts?
>>Ricardo Calumby.
>>Converse com seus amigos em tempo real com o Yahoo! Messenger

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