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ADSTEFAN
     
Principle
and Theory
The casting process can be divided
into two phases; first, the molten metal flows into the mold and second,
when the molten metal loses heat and solidifies. Casting defects
occurring in either phase are
distinct. The defects occurring during the flow are air
entrapment, cold shut etc., and those during solidification are
shrinkage cavity and segregation.
In
this software, the process of fluid flow and solidification are carried out
numerically in order to predict casting defects. （Refer Fig.1 and Fig.2）
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Figure 1 :
Schematics of the Die Cast process |
Figure 2 :
Schematics of shrinkage cavity |
Also, not only does this software enable the user to carry out the
calculations numerically, but it also has an exclusive pre processor to prepare
the input file, and a post processor to visualize the calculation results.
One of the main features of this software is the ease of use via the
simple GUI. It may take only half a
day's introduction of this software before the Engineers can start
running basic simulations.
One of the unique features of this software is its ability to handle
dual phase - air and molten metal at the same time during filling. （Refer Fig. ３）
In the past, this has been numerically challenging to model, but with
the incorporation of this phenomena, ADSTEFAN provides the user with
accurate and reliable results.
Figure 3 Free surface flow controlled by inertia force
Features
- RELIABILITY OF TECHNOLOGY
ADSTEFAN is an advanced and reliable
simulation system developed over a period of several years in collaboration
with Tohoku University and the Industry-University cooperation project
[Casting Organization (STEFAN)] and with experienced Engineers from over 30
Japanese casting companies.
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FAST CALCULATION
SPEED
Through a uniquely developed
numerical algorithm, the software performs quick and accurate. Typical
calculation time for a 1 million mesh model for fluid flow is 0.5 hr. with 20
MB Memory by (Pentium4) 2GHz.
-
HIGH ACCURACY
ANALYSIS
The unique algorithm incorporates
free surface calculations and accurate unsteady casting/non-linear analysis.
-
ABLE TO HANDLE
LARGE MESH
Able to handle large mesh data (over
20 Million mesh) on routine jobs. Calculations involving over 100 million
mesh elements have been analyzed using a PC without any numerical issues.
Functions
1
PRE PROCESSOR
・ 3D SHAPE INPUT
A basic drawing
module is available for the user to draw simple shapes using 2D and 3D
primitives (triangles, cubes,
polyhedrons, cones, columns). Also,
basic Boolean operations are
available for the users convenience.
・ CAD DATA MODULE
A module directly generates
a Finite Difference Mesh (FDM) by importing a 3D model (STL format)
into the system. Since most CAD packages can export a STL file from true
CAD, this module is very helpful. (Refer Fig.4, Fig. 5）
・
AUTOMATIC MESH GENERATION/MODIFICATION
The Enmesh module enables the user
to modify the mesh if necessary.
・ ANALYSIS/PARAMETER MODULE
Using this module, the user
can input all the parameters and boundary conditions that are necessary
to run the simulation.
 
Figure
4 3D CAD shape data Figure
5 FDM mesh created from CAD data
2 ANALYSIS MODULE
・
FLUID ANALYSIS
This module
carries out the heat transfer & flow analysis by considering the movement
of the 3D
free surface. Other functions like back pressure calculation, vacuum
considerations, tilt casting etc. are also available.
・ SOLIDIFICATION ANALYSIS
Solidification is carried out using the initial temperature condition
from the flow simulation. Defects such as shrinkage cavity and
porosities can be visualized using this module.
・
DIE
CASTING PROCESS
One of the unique points of this software is that the Engineer can
numerically visualize all the stages of die casting - i.e. die closing,
shooting of part, die opening, part extraction, lubricant spraying
etc. The Engineer can also visualize the cyclic temperature
fluctuation of the dies during the different stages of the process.
・
SLEEVE
ANALYSIS
Since ADSTEFAN can
handle large mesh sized models, it is possible to visualize the filling
sequence by incorporating the sleeve elements (plunger). This enables
the Engineer to visualize how the molten metal flows from the sleeve
into the cavity.
・ CSM: CYCLIC STEADY HEAT
BALANCE METHOD
This module assists in
visualizing the temperature fluctuation of the die during the casting
process by utilizing a unique algorithm that just takes a few minutes to
complete.
・ THERMAL STRESS ANALYSIS
Able to analyze the specimen or the die for deformation, stress, strain from
the temperature
distribution data.
・ SHRINKAGE SHAPE ANALYSIS
3 dimensional volumetric comparison between the cast part
and original CAD model is possible, giving the user an idea about the
location and shape of
distortion after solidification.
3
POST PROCESSOR
ADSTEFAN offers a variety of results
based on the modules listed above.
RESULTS OF FLUID FLOW ANALYSIS
Results include filling results, temperature
distribution, cold shut prediction, velocity vector, turbulence zone,
stress and deformation results. （Refer Fig. 6）
RESULTS OF SOLIDIFICATION ANALYSIS
Results pertaining to
solidification and shrinkage occurrence.
  
Figure 6 Results of Die Cast fluid flow analysis (different
stages of filling)
System Requirements
HARDWARE
MEMORY： Above
512MB
HARD
DISK：
Over 10GB
CD-ROM DRIVE
(* Specification for simulation of 10 Million elements)
OPERATION SYSTEM
Microsoft Windows
HP (HP-UX 10.X)
Sun (Solaris 2.6)
SGI (IRIX 6.X)
Linux (redhat7.2)
IBM （AIX 4.3）
COMPAQ-Alpha （Tru64 UNIX）
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