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)

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.

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.

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.

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