Eosint-M, Eosint-P

From: Stefan Nöken (Fraunhofer Gesellschaft), Yakov Horenstein (Electon)
To: RP-ML
Date: Tuesday, October 17, 1995
Subject: Eosint-M, Eosint-P
Stefan Noeken <NOE@ft1.ipt.rwth-aachen.de> wrote:
>we at IPT in Aachen are using the EOSINT-P system since June 1994. In
>the meantime a lot of research has been done; focus: investigation
>into the basic process principles for optimized part building!
     This doesn't go into any details, so in the absence of any other info, I
have appended below a compilation of facts from " Stereos & Eosint 1995 - New
Developments & State of the Art", and other material published by Eos in
June this year. Perhaps someone with practical experience can confirm or
deny any of this. I would be particularly interested in knowing about using
EOSINT -P polystyrene parts in casting applications.
     Why would someone choose Eos over DTM? One reason might be the bigger
workspace of the Eos machine.
Yakov

from:  "Stereos & Eosint 1995 - New Developments & State of the Art"

>EOSINT laser-sintering systems were introduced in 1994 as a logical
>complement to STEREOS. They share identical software and similar optics and
>controller but offer...different building materials. The 1st system EOSINT
>P was designed for thermoplastic materials such as polystyrene and nylon...
>Recently a new system called EOSINT M has been developed for
>direct sintering of metal powder....
>
>EOSINT P
>This system comes in 2 configurations (for different model sizes)
>Build space 340x340x(390 mm) 590 mm
>Materials: polystyrene and nylon
>Laser: CO2/50W
>Scanning speed: up to 2 m/s
>Layer thickness 0.1-0.2 mm
>Interchangeable containers allow for quick changes between materials...

>Applications for polystyrene: Investment casting patterns and functional
>prototypes
>Applications for nylon: functional components for injection molding in
>similar materials
>Advantages of polystyrene: low temperature sintering, low shrinkage, higher
>accuracy (+/- 0.1mm)
>Advantages of nylon: good mechanical properties (high strength, elasticity
>and elongation)
>
>Models built in polystyrene are ...well suited as investment casting
>patterns because they behave similarly to the commonly used expanded
>polystyrene foam. The surfaces must be sealed with wax...to prevent the
>ceramic slurry or plaster from entering the otherwise porous pattern.
>Several foundries have reported excellent experience with Eosint
>polystyrene patterns and confirmed that they can be used in the standard
>automated lost-wax process or flask process without any further
>modification. Very high success rates have been reported, and...costs are
>much lower than with other RP materials which require modifications to the
>process.
>
>Models built in nylon can achieve strengths of up to 90% or more compared
>to the equivalent injection molded part by selecting appropriate building
>parameters.
>
>Building times with Eosint P and polystyrene are significantly faster than
>with stereolithography. The porous sintered models can be infiltrated with
>materials such as epoxy resin to greatly increase the density, strength &
>hardness. By this means it is quite often possible to obtain prototypes
>suitable for functional testing while retaining the advantages of high
>building speed and accuracy (the paper here shows a photo of a housing
>170x170x190 mm and the resulting aluminum casting with the statement:
>"...the entire project from CAD data to aluminum prototype was completed
>within 2 1/2 weeks").
>
>EOSINT M
>Introduced at the end of 1994, it is the world's first commercial system
>for direct laser sintering of metal powder. No polymer or other organic
>binder is used...The material currently used is a special alloy mixture
>comprising mainly bronze and nickel, developed by Electrolux...This metal
>can be sintered without pre-heating and exhibits negligible net shrinkage
>during the sintering process. This fact, combined with layer thicknesses
>down to 0.1mm enables parts to be built typically with 0.1mm accuracy. The
>machine builds parts up to 250x250x150mm.
>
>The main application is rapid tooling. In contrast to other methods which
>require multiple stages of replication or burning out polymer binder,
>Eosint M uses a single stage process to build a metal tool which is hard
>enough to be machined or polished. This porous tool can be used directly
>for some forms of low-pressure molding, or can be infiltrated with
>materials such as tin or epoxy resin to achieve high density and a good
>surface finish. The infiltration...has a negligible effect on the high
>accuracy of the part, and further polishing enables a fine surface finish
>suitable for injection molding..The molds can also be post-processed in
>other ways, for ex. by electro-plating.