International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 312
(ICCOMIM - 2012), 11-13 July, 2012
ISBN 978-93-82338-04-8 | © 2012 Bonfring
Abstract--- Casting produced by a foundry is acceptable if its quality level as required by the customer’s
specifications is found satisfactory. Otherwise the casting is termed as defective; each casting rejected contributes to
the wastage and loss of value to the foundry. A sound casting involves systematic blend of experience and
engineering basics. For improving cast metal yield, optimize the gating system design, optimise mould filling, avoid
shrinkage scrap, voids, hot tears etc. Casting simulation packages were found to be of immense help. With the
advent of modern computing facilities, application of some popular commercial software as casting simulation tools
has become widely accepted within the foundry industry. The aim of the present paper is to produce defect less
castings by simulation of sand casting phenomenon for this a case study on steel component was carried out using
ProCAST, a commercial finite element solver developed by ESI group. Observation of the simulation results was
carried out experimentally. Efforts were made to improve the yield of castings, minimize the shrinkage porosity,
casting parts resulting in lower cost and higher productivity.
Keywords--- Simulation, Mould Filling, Solidification, Quality and Yield
I. INTRODUCTION
OST of the steel foundries must melt about twice as much steel as will be shipped as finished product. The
additional metal is primarily present in risers, which provide feed metal that helps prevent holes or voids from
forming inside the casting as it solidifies. This paper is identifying techniques for decreasing the size and number of
risers required to produce quality castings, and high yield. Metallurgical phase transformation plays a vital role in
the solidification of castings [1]. Computer simulation of casting solidification of metals and alloys is a complex
phenomenon [2,3]. The assumptions and constraints used for simulation are considered as a vital one [4,5]. In the
casting process, the metal–mould interface will have an air gap which affects the dissipation of heat flow from the
casting to the mould [4,6]. But the application of pressure during the solidification process reduces the air gap and
forms a tight contact between the casting and the mould [7,8]. This condition releases the heat at a faster rate and
produces fine grain structured castings [9]. To identify the conditions and optimum values, simulation of
solidification process is done by running indigenously developed computer software for the casting process selected
for investigation [10,11]. The program output provides the details on time-temperature profile and heat transfer
coefficient values which plays a key role in the effective design of castings [11,12].
1.1. Applications of Casting Solidification Simulation Software Programs Casting solidification simulation software‟s are in regular use by aluminium, copper, iron and steel foundries
using processes ranging from green-sand, resin-and shell-bonded sand to investment and gravity die casting.
Applications include [13]:1. Large steel castings such as heavy weighing turbine housings and stern frames where
improved yields and reduced fettling costs were achieved.2.Critical high pressure valve castings.3.Repetition
castings such as ductile iron crank shafts, where modelling increases the chance of achieving „right first time‟
methoding, so reducing the lead time for new castings. Solidification simulation software‟s are not only used by
foundry method engineers but also casting designers and purchasers are using the software‟s having experienced
significant improved quality from their simulation software-using suppliers.
1.2. Available Numerical Techniques for Casting Solidification Simulation Process
Some of the well-known casting simulation programs currently available to foundry engineers are listed in Table
P. Prabhakara Rao, Kakatiya Institute of Technology & Science. E-mail: [email protected]
Dr.G. Chakraverti, Mahaveer Institute of Science & Technology. E-mail: [email protected]
Dr.A.C.S. Kumar, P.Indra Reddy Memorial Engineering College.
PAPER ID: MEP16
Casting Quality and Yield Improved by
Simulation P. Prabhakara Rao, Dr.G. Chakraverti and Dr.A.C.S. Kumar
M
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 313
(ICCOMIM - 2012), 11-13 July, 2012
ISBN 978-93-82338-04-8 | © 2012 Bonfring
1.2[14].Among these, AutoCAST, MAGMASoft, ProCAST, and SOLIDCast have the largest installation base in
India
Table 1.2: Casting Simulation Programs [14]
Software Program Company and Location
CastCAE CT-Castech Inc. Oy, Espoo, Finland
Castflow, Castherm Walkington Engineering, Inc., Australia
PAM-CAST/ProCAST ESI Group, Paris, France
MAGMASoft MAGMA GmbH, Aachen, Germany
JSCast Komatsu Soft Ltd., Osaka, Japan
SOLIDCast Finite Solutions, Inc., Illinois, USA
MAVIS Alphacast Software, Swansea, UK
AutoCAST Advanced Reasoning Technologies P. Ltd., Mumbai
On estimating the defects in the casting components major portion is because of the design problems and minor
portion is caused by manufacturing. The cost involved is also very high. Casting process simulation and analysis for
various defects is considered to be one of the major productivity tools. Considering the conventional approach
followed in foundries shown in Figure:1.3, i.e. trial and error method, lots of money, energy and time are wasted.
Even then process is not controlled accurately. Foundries mostly follow lot of heuristics which they come out with
their experience in that casting. Process operations and casting are to be controlled in a very accurate fashion. One of
the approaches that can be adopted is simulation, which is now becoming a part of every industry. Computer aided
casting simulation helps us in visualizing the real world environment casting process in a mere few steps of inputs.
Simulation has become an important tool in almost in all foundries. Simulation plays a major role in all casting
stages. The main aim of all the foundry makers will be to produce profitable and high quality components to survive
in this competitive era. This may be one of the reasons “why now a day‟s simulation has become an unavoidable
part of casting production.
II. CASTING PROCESS MODELLING
An engineer designing the particular production technology of a casting has certain possibilities of interfering
with the process of solidification and cooling – among others through proper designing of technological allowances,
internal and external chills, distribution and magnitude of riser heads, assuming optimum temperature of pouring
and chemical analysis of the alloy, and finally through a suitable selection of sand mix. The process of designing the
technology of a casting production can be expanded, modernized and improved through utilization of the
possibilities offered by the introduction of numerical methods in the calculation of solidification and cooling of
metal in a mould.Generally the simulation software has three main parts shown in Figure2.
Pre-processing: the program reads the CAD geometry and generates the mesh,
Main processing: adding of boundary conditions and material data, filling and temperature calculations,
Post processing: presentation, evaluation.
The objective of the present paper is to optimize gating/riser systems based on CAD and simulation technology
with the goal of improving casting quality such as reducing incomplete filling area, decreasing large porosity and
increasing yield. Therefore in this paper a case study on plate casting simulation technology based optimization
framework is presented. Given a CAD model of part design and after its being converted to casting model, the
objective is to evaluate casting design. Then runner and risers are presented parametrically. By varying each
parameters, after analyzing simulation results, the original gating/riser system design will be optimized to improve
casting quality.
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 314
(ICCOMIM - 2012), 11-13 July, 2012
ISBN 978-93-82338-04-8 | © 2012 Bonfring
Figure 1.2: Conventional Production Steps in a Typical Sand Casting Process
Figure 2: System of Simulation
Computer simulation based on the design procedures described above have been implemented with one case
study. Let's consider a crusher plate casting for the present study (Figures.2.1 &2.2Shows the 3D model&3D model
of sand block). Used in cement industry made of IS 1030 alloy steel. During simulation of the casting process,
mould filling and solidification are examined and sand casting process are optimized.
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 315
(ICCOMIM - 2012), 11-13 July, 2012
ISBN 978-93-82338-04-8 | © 2012 Bonfring
Figure 2.1: 3D Model of Plate Figure 2.2: 3D Model of Sand Block
III. MOULD FILLING AND SOLIDIFICATION SIMULATION RESULTS USING PROCAST
The Procast simulation solved for mould filling and solidification processes at the same time. The discussion
about mould filling is solely based on ProCAST simulation results. The mould filling processes of the initial and
modified gating systems can be visualized from Figures.3.1&3.2. It is found that for every succession of one second
fraction of solid and temperatures are changing (encompasses pouring basin, sprue and runner system, gatings,
casting and feeder) will be filled up. The melt was rising almost uniformly in the cavity of the mould until it was
completely filled up. This is a good filling because it ensures the temperature distribution in the mould will be equal
everywhere just after filling so that solidification rate will be fairly consistent throughout the casting. Equal rate of
solidification will entail uniform shrinkage of the casting to minimize defects such as shrinkage cavities as a result
of non-uniform cooling rate. The temperature distribution and fraction of solid also indicates that during mould
filling, cooling has actually started especially at the end of runner as shown from Figures.3.3&3.4. It can be seen
that down sprue and feeder were filled up simultaneously since their dimensions and shapes are very similar.
Though the down sprue is the entrance of the molten metal, it was not filled up or completely wetted during the
mould filling of cavity. Generally, the mould filling is successful as a result of proper design of straight runner
system. It can be seen that the straight runner and gatings were filled up with in the first few second.
Figure 3.1: Mould Filling Pattern and Temperature Variations of Initial Gating System at Various Stages
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 316
(ICCOMIM - 2012), 11-13 July, 2012
ISBN 978-93-82338-04-8 | © 2012 Bonfring
Figure 3.2: Mould Filling Pattern and Temperature Variations of Modified Gating System at Various Stages
Figure 3.4: Solidification Fraction of Modified Gating
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 317
(ICCOMIM - 2012), 11-13 July, 2012
ISBN 978-93-82338-04-8 | © 2012 Bonfring
Figure 3.3: Solidification Fraction of Initial Gating System at Various Stages
IV. CONCLUSIONS
Casting simulation is the way of predicting a casting process. The objective function of maximizing the yield,
minimizing shrinkage and minimizing solidification time are all found to be greatly achieved using ProCAST FEA
based software. Simulation should become an indispensable tool in all foundries, minimizing time, energy spent and
money, thus maximizing profit. The plot for various parameters and defects very well gives a good idea for redesign
and re-simulation done with no cost of time. Casting process simulation has become an industry standard. No
foundry that produces high quality castings can consider simulation as unnecessary.
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