International Journal of Engineering Research and Development (IJERD) Simulation

International Journal of Engineering Research and Development (IJERD)
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Download-> http://www.ijerd.net/Journalcureentissue.asp -> Volume 1, Issue 1
SIMULATION IN THE PRODUCTION OF CO2 SAND CASTING
COMPONENTS
P. Prabhakara Rao1
, Dr.G.Chakraverti2
, Dr.A.C.S.Kumar3
1
Department of Mechanical Engineering, Kakatiya Institute of Technology &Science,
Warangal,Andhrapradesh India
2
Director (R&D); Mahaveer Institute of Science and Technology, Hyderabad
3
Principal, Abhinav Hi-Tech College of Engineering, Himayath Nagar, Hyderabad
ABSTRACT
The simulation programs are used to achieve sound, high quality castings. The use of
computer simulates mould filling and solidification has helped Foundry industry assure the
quality of its castings with a higher degree of confidence, and reduce the cost of rejects. The
effective use of this software package has resulted in major improvements being realized in
the areas of controlling shrinkage porosity, inclusions and cold run defects. It has also
contributed towards lowering the cost of methoding; the numerical simulation of casting
processes is finding a steadily growing acceptance in the foundry industry worldwide.
Advanced computer technologies like ProCAST have turned out to be powerful tools for a
continued process optimization. In this paper we investigate the importance of heat transfer
in the Solidification simulation of straight bar and flanged bar steel castings in co2 sand
moulds is presented .The paper also deals with the interpretation of simulation results and
their relationship to real foundry defects in a precise manner.
KEY WORDS: Casting simulation, Steel Castings, Mould filling, and Solidification of CO2
Sand Castings.
I. INTRODUCTION
ProCAST is a three dimensional solidification and fluid flow package developed to
perform numerical simulation of molten metal flow and solidification phenomena in various
casting processes, primarily die casting (gravity, low pressure and high pressure die casting)
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Volume 1, Issue 1 July - August (2013) Pages: 30-40
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and sand casting. It is particularly helpful for foundry applications to visualize and predict the
casting results so as to provide guidelines for improving product as well as mold design in
order to achieve the desired casting qualities.[8] Prior to applying the ProCAST extensively
to create sand casting and die casting models for the simulation of molten metal flow (mold
filling) and solidification (crystallization in the process of cooling).the cast and mold design
of the experiment is transformed into a 3D model and imported into ProCAST to conduct the
sand casting process simulation . Sand casting is the casting process that has the longest
history. Sand casting still accounts for the largest tonnage of production of shaped castings.
This is due to the fact that sand casting is economical and possesses the flexibility to produce
castings of any material and the weight of castings can be range from tens of grams to
hundreds of tons. Conventional sand casting is not a precision process and requires after-cast
machining processes and surface finishing producing the required dimensions and surface
quality. However, advanced high technology sand casting process (improved sand quality and
mold rigidity) enables this method to produce higher precision cast Products with better as-
cast surface finishing that reduce the cost of after-cast touch-up. This will enhance the
capability of sand casting to produce ‘near-net-shape’ products and improve its
competitiveness. Most sand molds and cores are made of silica sand for its availability and
low cost. Other sands are also used for special applications where higher refractoriness,
higher thermal expansion are needed. The average grain size ranges from 220 to 250 microns.
In the present work simulation of mould filling solidification of alloy steel castings of co2
sand moulds are carried and to compare with the experiments.
II. METHODOLOGY
Figure 1 shows a flowchart, in which 3D CAD and simulation tools are utilized to
improve the system Design of the casting. The castings geometries presented here were
meshed with Mesh CAST, which requires the. Generation of a surface mesh before meshing
the enclosed region with tetrahedral elements. The computational conditions used in all
simulations were the same. Figure 2 shows a flowchart,[2] where is represented the steps
needed to make a simulation.
Table 1 – Initial Conditions
Mould Temperature(0
C) Metal Temperature(0
C) Fill velocity
30 ºC 1450 ºC 0.10m/s

32
Figure 1- procedure to improve the design of new casting

33
Figure 2-Flow pattern of computer simulation.
III. NUMERICAL SIMULATION
3.1 Original Casting
The geometry was taken from the foundry with original assembly 3D CAD model in
Para solid format shown in Figure 3. Figure 4 shows a finite-element mesh of the original
geometry by Mesh CAST. The existence of Symmetry planes allow the simplification of the
geometry. In the pre-processing, a virtual mould was created. The material properties of the
metal – IS1030 – and mould [6] were applied to the respective model, as well as the
interfaces, boundary conditions [8] and the initial conditions of the model, Table 1. After the
pre-processing, the finite-element model was solved using the software ProCAST. The results
of simulated filling and solidification time were confirmed by their practical agreement. The
quantitative analyses of macro porosity (Figures 5.a,5.b and 5.c) showed macro porosity
values of 0.2-0.6% And original castings were sent for NDT testings (Figure 6.a) and 6.b)

34
shows the liquid pentrant test results which are not in agreement with the good real castings.
The analysis has shown that it is possible to simulate realistic filling and solidification time
by the finite element method with reasonable results. However, there are some uncertainties
associated with thermo physical properties or boundary conditions that drive at unrealistic
macro porosity results. So, we assumed that in this case the input numerical parameters give
some safety margin.
Figure 3 – Original 3D CAD casting Figure 4 – Simplified finite-element mesh of
original geometry
Figure 5.a) – Macro porosity prediction in the original geometry.(simulation result)

35
Figure 5. b) – Macro porosity prediction in the original geometry.(simulation result)
Figure 5.c) Macro porosity prediction in the original geometry.(simulation result)

36
Figure 6.a) – macro porosity in real Figure 6.b) – macro porosity in real
casting casting
3.2 Modified Casting
In order to perform a reduction in the poured metal some modifications were made in
the feeding system. The achieve solution in terms of results closely approaches with the
simulation of the original casting. The proposed geometry is presented in Figure 7. Figure 8
shows a finite-element mesh of the modified geometry by MeshCAST. The existence of
symmetry planes allows the simplification of the geometry. Figure 9 presents the fill flow
distribution 50 seconds after pouring. With this analysis type it is possible to detect
turbulence and unsteady flow behavior. Also it is possible to analyze the optimal filling
sequence. Figure 10 presents the prediction of shrinkage hot spots. By making the solidified
metal transparent, users can easily see the remaining liquid pool. An isolated region of liquid
thus suggests a potential hot spot and macro shrinkage indication. Figure 11.a), 11.b) and
11.c)shows the macro porosity prediction results at the modified geometry for two cross-
sections; we can see a macro porosity range at about 0.2 - 0.09 %, at the different position
with compared to previously detected at Figure 5 .a),5.b) and 5.c)

37
Figure. 7 – Modified 3D CAD Figure. 8– Simplified finite-element mesh
of the modified geometry
Figure .9 – Temperature distribution 50 seconds after pouring

38
Figure .10 – Solid fraction after 436 seconds of pouring
Figure 11.a) – Macro porosity prediction in the modified geometry

39
Figure. 11.b) – Macro porosity prediction in the modified geometry
Figure .11.c) – Macro porosity prediction in the modified geometry
IV. EXPERIMENTAL VALIDATION
After the results obtained by the simulation, the foundry made a new layout in
agreement with the Modified casting and some pouring tests were made. The casting was sent
for NDT testings and tests are confirmed there were no major defects observed in the
castings.

40
V. CONCLUSIONS
Computer simulation has opened the possibility of creating, analyzing, and
optimizing virtual casting so that defect free real castings can be produced The use of
CAD/CAE software greatly improves the speed and accuracy of decision-making in
individual tasks involved in casting development for a new product (application). For this
present paper the implementation of CAD/CAE is done on the alloy Steel flanged bar casting.
Flanged bar steel casting showed considerable macro porosity shrinkage after first foundry
trial. Modeling and analyzing the casted bar indicates prone to shrink at flanged ends. This
macro porosity is minimized with the modification of gating and a riser design is proposed.
And their effect on accuracy and quality of casting is analyzed. This proposed modification
in gating design is satisfactory .Further utilize and explore the application of Procast not only
on sand casting but also gravity die casting, low pressure die casting and high pressure die
casting and investment casting.
REFERENCES
1. Application of Commercial Software Package “Procast” to the Prediction of Shrinkage
Porosity in investment Castings.www.mmat.ubc.ca/databases/Details.asp?id=354
2. Reciprocating Engines Never Had it so Good.
www.autofieldquide.com/articles/079801.html
3. Gating Design via Computer Fluid Flow Modeling.
www.moderncasting.com/archive/feature 019 01.html
4. Viswanathan, W.D.Porter, Using of Simulation in Optimizing Mould Filling,
AFSTransactions 98-59, 477-483.
5. Nyamekye, K; Sufie - Wei, computer application for finding the Thermal fatigue life in
permanent mould, AFS 4th
International Conference on Permanent Mould Casting of
aluminum – Anaheim, CA, Nov 1997(18p).
6. 1999 Casting Simulation Software Survey.www.moderncasting.com/archive/feature
030.asp
7. Casting Simulation as a Tool in Concurrent Engineering, International ADI and
Simulation Conference, May 28-30, 1997.
8.J.Campbell,Casting,SecondEdition,Butterworth-Heinemann, Oxford, 2003.
9. J. Davies, Heat transfer in gravity die castings, British Foundryman 73 (1980) 331-334.
10.A. Meneghini, L. Tomesani, G.S. Cellini, Relation between HTC evolution, gap
formation and stress analysis at the chill interface in aluminium sand casting, Proceedings
of the 136th Annual Meeting and Exhibition “TMS 2007: Linking Science and Technology
for Global Solutions”, Orlando, 2007, 241-248.

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