CASTING SIMULATION OF WHEEL HUB USING ADSTEFAN SIMULATION · PDF fileCASTING SIMULATION OF WHEEL HUB USING ADSTEFAN SIMULATION SOFTWARE Keertikumar1, Bharat.S.Kodli2, Santhosh Kumar

NCADOMS-2016 Special Issue 1 Page 466

CASTING SIMULATION OF WHEEL HUB USING ADSTEFAN SIMULATION

SOFTWARE

Keertikumar1, Bharat.S.Kodli

2, Santhosh Kumar A. S

3, S Shamasundar

4

1M.Tech Scholar, Department of Mechanical Engineering, PDA College of Engineering, Gulbarga, VTU,

Karnataka, India. 2PG Coordinator, Department of Mechanical Engineering, PDA College of Engineering, Gulbarga, VTU,

Karnataka, India. 3Senior Application Engineer, ProSIM R&D Pvt, Ltd, Bangalore. Karnataka, India.

4Managing Director, ProSIM R&D Pvt, Ltd, Bangalore. Karnataka, India.

Abstract: Sand casting is a manufacturing process most widely used in automobile industries, especially in

automotive products. Many researchers reported that about 70% of the defects in castings are due to wrong

design of gating and risering system and only 30% due to manufacturing problems. In this paper optimization of

gating and risering system by replacing existing trial and error method with the help of CAD modeling (CATIA

V5) and casting simulation software ADSTEFAN was carried out. The simulation results are used to optimize

the gating system to improve Directional, Progressive Solidification and reduce shrinkage. Through several

simulation iterations, it was concluded that defect free casting could be obtained by modifying the sprue

location and providing the risers and exothermic sleeves at location porne to formation of shrinkage porosity

lead to the decreasing size of shrinkage porosity and shifting the shrinkage porosity from component to the

risers.

Keywords – Casting, Simulation, Gating System, Optimization, Shrinkage, Fluid flow, Solidification, Wheel

Hub…

I. INTRO DUCTIO N

Casting is the one of the manufacturing process which is used for making complex shapes in which a

molten material is poured into a mould cavity, which contains a mold cavity of the desired shape and then

allowed it to solidify. The solidified part is also known as a casting, which is removed from the mould box to

complete the process [1]. Inspite of conventional knowledge of gating and riser system design and suggestions

by experienced foundry engineer’s wheel hub showed the presence of shrinkage cavity. Producing defect free

casting is a challenge in manufacturing environment. The formation of various casting defects is directly related

to fluid flow phenomena during the mould filling stage and in the cast metal. The rate of solidification greatly

affects the mechanical properties such as strength, hardness, machinab ility etc [2]. One of the critical elements

that has to be considered for producing a high quality sand casting product is the gating system design and

risering system design [3-4]. Any improper designing of gating system and risering system results in cold shut

and shrinkage porosities. Therefore adequate care is necessary in designing gating and risering system to obtain

defect free casting.

Casting simulation minimizes shop floor trials, time, cost and work force to achieve the desired internal

quality at the highest possible yield. Hence with conventional approach, finding an acceptable gating system

design proves to be an expensive process so a number of casting simulation software’s are available today, such


as ADSTEFAN, AutoCAST, CAPCAST, AnyCasting, CastCAE, MAGMA, MAGMASOFT, Flow-3D,

Novacast, NovaFlow, SoftCAST, SUTCAST, Virtual Casting, WINCAST, ProCAST and SolidCAST [5]. Most

of them use Finite Element Method to discretize the component to solve the solidification and fluid flow

equations. Presently use of casting simulation software is increasing, as it essentially replace or minimizes the

shop floor trails to achieve sound casting. With the availability of modern numerical software and good

hardware capabilities, simulation has become an important tool for design, analysis and optimization of casting

processes. Use of casting process simulation software can significantly reduce the casting cost, lead time and

enhance the quality of casting [6].

ADSTEFAN(Advanced Solidification Technology for Foundry Aided by Numerical Simulation) is

three dimensional solidification and fluid flow package developed to perform numerical simulation of molten

metal flow and solidification phenomena in various casting processes, primarily sand casting and die casting

(gravity, low pressure and high pressure die casting). It is particularly helpful for foundry application 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. Prior to applying the ADSTEFAN extensively to create sand

casting and die casting models for the simulation of molten metal flow(mould 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 ADSTEFAN to conduct the sand casting process simulation.

Many software use finite element method (FEM) to simulate casting process, which needs manual meshing and

are prone to human errors. The casting simulation software used in the present work uses Finite Difference

Method (FDM) using cubes as the basic elements and has a major advan tage over FEM. It meshes automatically

eliminates the need to recheck the meshing connectivity there by speeding up analysis. In the present riser

system has been designed and optimized by iterative process through fluid flow and solidification simulation for

a wheel hub to produce defect free casting [6].

The main inputs include the mould cavity geometry (includes the shape, size and location of cores,

bosses, ribs, mold cavity, risers, runners, ingates and sprue.), thermo-physical properties (density, specific heat,

latent heat, volumetric contraction during solidification, viscosity, surface tension and Thermal conductivity of

the cast metal as well as the mold material, as a function of temperature), boundary conditions (such as the

casting-mold, casting-chill, casting-exothermic sleeve, casing-die, die-cooling channels heat transfer coefficient,

for normal mould as well as feed-aids including chills, insulation and exothermic materials) and process

parameters (such as pouring time, pouring rate and temperature). The results of solidification simulation include

color-coded freezing contours at different instants of time starting from beginning to end of solidification. This

provides a much better insight into the phenomenon compared to shop -floor trials (real molds being opaque).

The user can verify if the location and size of feeders are adequate, and carry out iterations of design

modification and simulation until satisfactory results are obtained. Sometimes, it is not possible to achieve the

desired quality by changes to method (mainly feeding and gating) alone. In such an event, it may become

necessary to redesign the part design.

The size and location of the runner, ingates, riser and sprue is an important input parameter for

solidification simulation. Considerable re-designing and experience of the user will help in taking the right

decision. Further by using the CAD software (CATIA V5) the solid model of the component with runner,


ingates, riser and sprue is to be designed by the engineer and imported STL ( Stereo Lithography) file into the

casting simulation program (ADSTEFAN) for each iteration. These all tasks requires computer skills and

designing knowledge. The accuracy of the results (such as solidification time, fluid flow and shrinkage defect s)

are influenced by geometry of the component and availability of temperature dependent material property

database. The simulation of complex intricated casting may consume more time and cost than shop-floor trials

and further delay and expenses occur due to the wrong feeding of the input parameters in the casting simulation

program [5].

The sand casting (green sand) casting process utilizes a cope (top half) and drag (bottom half) flask of

sand (usually silica), clay and water. When the water is added it develops the bonding characteristics of the clay,

which binds the sand grains together. When applying pressure to the mold material it can be compacted around a

pattern, which is either made of metal or wood or wax or plastic to produce a mold cavity havin g sufficient

rigidity to enable metal to be poured in it to produce a casting. The process also uses cores to create cavities

inside the casting. After the molten metal is poured into mold cavity and allowed it to cool, then the core is

removed from the casting. In this process material cost is low and the sand casting process is exceptionally

flexible. In this process simulation is carried out for manufacturing of Wheel Hub and the results were obtained

[7].

II. CASTING SIMULATIO N

Computer simulation of casting process has emerged as powerful tools for achieving quality assurance

without time consuming trials. This includes mold filling, fluid flow, solidification, stresses and distortion. It

requires part model of component and tooling (parting line, mould layout, cores, feeders, chills, exothermic

sleeves, filters and gating system), temperature dependent properties of component and mold materials, input

process parameters (pouring time, pouring rate, direction of fluid flow, etc.). The simulation results are

interpreted to predict casting defects such as hot spots, misrun, cold laps, cold shut, blow holes, pin holes, gas

porosity, shrinkage porosity, cracks and distortion etc., For a product design engineer inputs are not easily

available which required considerable experience and expertise in the simulation software. In the simulation

process the tooling and product design process will run simultaneous in parallel manner to evolve the quality

product. This approach towards improve the quality of product simu ltaneously is referred as concurrent

engineering [5].

III. MATERIAL AND METHO DO LO GY

Wheel Hub is usually made of SG500/7 (FCD500), it is a bridge between Shaft and wheel. Chemical

composition of SG500/7 (FCD500), material is as shown below table.

Table 1: Chemical composition of SG500/7 (FCD500)

Alloyant Carbon

(C)

Silicon

(Si)

Manganese

(Mn)

Sulphur

(S)

Phosphorous

(P)

Magnesium

(Mg)

Iron

(Fe)

Wt% 3.48 2.70 0.20 0.01 0.05 0.24 Balance

Figure 1 shows the CAD model of Wheel Hub. The wheel hub casting model with the essential

elements of gating system are sprue, runner, ingates and riser system were generated in CATIA V5 CAD

software. In the first iteration (fig 1) the sand riser is used for the casting of wheel hub, after the simulation of

first iteration the shrinkage porosity defect is occurred. In order to obtain sound casting the model has to be re -


designed in such way that in the final case the exothermic sleeves are used to keep riser metal in the molten

condition so that it is used to compensate the s hrinkage porosity to achieve the directional, progressive

solidification and achieve defect free casting with good yield rate (fig 2). The dimensions used in iteration 1 and

8 are tabulated in the below table (2).

Table 2: Iteration design dimensions

Iteration 1 2 3 4 5 6 7 8

Sprue (mm)

Øb 30 30 30 30 30 30 30 30

Øt 40 40 40 40 40 40 40 40

H1 300 265 235 235 245 240 250 250

Runner

(mm)

W1 31.02 31.02 31.02 31.02 31.02 31.02 31.02 31.02

L1 31.02 31.02 31.02 31.02 31.02 31.02 31.02 31.02

H2 31.02 31.02 31.02 31.02 31.02 31.02 31.02 31.02

Ingate (mm)

W2 12.7 12.7 12.7 12.7 12.7 12.7 25.33 25.33

L2 50 50 50 50 50 50 50 50

H3 25.33 25.33 25.33 25.33 25.33 25.33 25.33 25.33

Riser

(mm)

Ø 97.5 97.5 97.5 97.5 97.5 97.5 97.5 105

H4 350 325 300 280 290 260 180 180

Exothermic Sleeve

(mm)

Øi

Not Used

97.5 97.5 97.50 97.50 105

Øo 112.5 112.5 112.5 112.5 120

H5 295 305 275 195 195

Total weight of casting with gating (Kg)

Kg 173.75 159.32 146.55 144.89 137.91 127.39 118.81 121.81

Yield % % 53.87% 58.75% 63.87% 64.60% 67.87% 73.19% 78.78% 76.78%

Pouring time(Sec)

Second 60.32 57.76 55.40 55.08 53.74 51.75 56.00 56.00

Defect Yes Yes Yes Yes Yes Yes No No

Øb=Bottom diameter of sprue, Øt=Top diameter of sprue, H1=Height of sprue,

W1=Width of runner, L1=Length of runner, H2=Height of runner,

W2=Width of ingates, L2=Length of ingates, H3=Height of ingates,

Ø=Diameter of riser, H4=Height of riser, Øi=Inner diameter of sleeves,

Øo=Outer diameter of sleeves, H5=Height of sleeves.


Fig: 1 Wheel Hub with gating system (Iteration 1)

Fig: 2 Wheel Hub with gating system (Iteration 8)

Fig: 3 Methodology used in simulation process

IV. SIMULATIO N PRO CESS

ADSTEFAN is casting simulation software developed by Hitachi Corporation Ltd Japan. This was used to

simulate fluid flow and solidification of casting components . Casting simulation and result analysis was done to

predict the molten metal solidification and fluid flow behavior inside the mould. The casting component with

gating system was imported in STL (Stereo Lithography) format to the ADSTEFAN software and meshing of

the model was done in the pre-processor mesh generator module. The appropriate mesh size of casting is taken.

The boundary conditions are feeded in to the system. Assignment of material properties, fluid flow and

solidification parameters: The meshed model was taken into the precast environment of the software, where the

material, type of mold used, density of cast material, liquidus and solidus temperatures of cast iron and other

input parameters of fluid flow and solidification conditions like pouring time, pouring type, direction of gravity


etc. were assigned. Table 3&4 show the material properties, fluid flow & solidification parameters. After the

assignment of material properties and s imulation conditions, predication of air volume, filling temperature,

filling velocity, solidification pattern, temperature distribution and soundness of degree are carried out. Casting

simulation program provides output files in the form of graphical images and video files which are analyzed to

predict defects after the successful execution [6].

Table 3: Input material properties and conditions

Parameters Type of Mold Conditions

Material Green sand SG 500/7 (FCD500)

Density 1.5 gm/cm3 7.2 gm/cm

3

Initial Temperature 40 1410

Liquidus Temperature - 1150

Solidus Temperature - 1145

Table 4: Input and output data of fluid flow and solidification parameters

V. RESULTS AND DISCUSSIO N

1. Air Entrapment

Figures 4 (a) & (b) shows the molten metal (grey color) at the bottom portion and air sweeping (blue color)

from the top portion of mould cavity. From the simulation results it is clear that from the nine ingates mold

cavity is filled with molten metal, air escapes through the top of the housing i.e. from the mold cavity to the

atmosphere through risers. Fig (a) and (b) shows pattern of air escape from the mold cavity. Hence this

simulation results helps to identify air entrapment defect in the casting . By this simulation result it is clear that

there is no air entrapment defect in the casting hence no need of modification in the design of gating system.

Parameters Input Conditions

Filling time 56 Seconds

Pouring type Gravity pouring

Gating Ratio 1:2:1.5

Output files

1. Air Entrapment

2. Filling Temperature

3. Filling Velocity

4. Solidification pattern

5. Temperature Distribution

6. Soundness of degree


a. Slide no 51 (50% ) b. Slide no 101 (100% )

Fig: 4 Air Entrapment

The ingates and runner are placed in a proper location due to which uniform flow of molten metal makes

the air gently to rise above, as the metal starts filling from the bottom of the cavity. This allows all the air and

gases to escape from the mould cavity. There is no air entrapped zone in the casting component and gating

system in all iterations.

2. Filling Temperature

a. Slide no 51 (50% ) b. Slide no 101 (100% )

Fig: 5 Filling Temperature

Figure 5 (a) and (b) represent the temperature distribution of the casting at different regions at specific

time. Figure (a) shows the temperature distribution of the casting at 27 seconds, figure (b) shows the

temperature distribution of the casting at 56 seconds. The red color represent the molten state of the casting


material and dark blue color represent the solidified casting. From the figure it is clear that, there is no sudden

temperature drop occurred during the fluid flow process, the fluid flow is laminar or uniform flow.

3. Filling Velocity

a. Slide no 51 (50%) b. Slide no 101 (100%)

Fig: 6 Filling Velocity

The fig 6 (a) and (b) represent Filling velocity at which the particular part of the casting component is filled

by the molten metal. The figure (a) represent the 50% portion of mold is filled within 27.28 seconds and figure

(b) represent the 100% portion of mold is filled by molten metal within 55 seconds, it clearly depicts that the

part that last to be filled is the riser. This is again a positive result of the casting simulation as riser solidify at the

last, can compensate material for casting. So there is no filling related defects like turbulences and the sand

erosion in the casting, this results are favorable to obtain sound casting in all cases.

4. Solidification Pattern

In order to achieve sound casting it is necessary to provide the directional solidification. The directional

solidification starts from thinnest section to thickest section and which ends at riser. The actual solidification of

metal begins at liquidus temperature of 1410°C. The solidification of metal ends at solidus temperature.

a. Slide no 100 (100% ) (Iteration 1) b. Slide no 100 (100% ) (Iteration 8)

Fig: 7 Solidification pattern


In figure 7 (a) first iteration the sand risers are used for the wheel hub casting process where the isolated

regions or hot spots are observed at the neck of wheel hub component so isolation area prone to defective area.

So in first case the figure (a) shows the outer surface of the riser which is in direct contact with atmosphere are

solidified faster as heat transfer take place earlier. In order to solidify riser at last, in final case exothermic

sleeves are used which prevent the transfer of heat from the riser and restrict the solidification of metal in the

riser. In this simulation result we come to know that the riser solidifies at the last which provide the directional

solidification of wheel hub casting in the final case. Hence final case results the sound casting of wheel hub.

5. Temperature Distribution


Fig: 8 Temperature distribution

The actual solidification of metal begins at liquidus temperature of 1410 °C (reddish yellow color). The

solidification of metal ends at solidus temperature (blue color). Figure 8 (a) shows the temperature distribution

of the molten metal in the first iteration of the gating system. There is no sudden temperature drop below the

liquidus temperature. In final cases as shown in figure 8 (b) the temperature distribution is also uniform. In all

the iterations it can be seen that runner bars and in-gates have temperature distribution within the limit i.e. above

liquidus temperature. Any sudden drop in temperature within the gat ing elements would have resulted in

formation of cold shuts and blockage of further entry of molten metal which has not been observed in the all

simulations results.

6. Soundness of Degree



Fig: 9 Soundness of Degree

Figure 9 (a) shows shrinkage defect is present at the neck of wheel hub component in the first iteration

simulation. The redesign of the gating system is necessary to eliminate the shrinkage defect. But in the final case

simulation fig 9 (b) represents the shrinkage is reduced by the decreasing the height of riser and providing

exothermic sleeves at the proper location. Thus volume of shrinkage defect decreased significantly. The

shrinkage defect is completely shifted to the riser this leads to the defect free wheel hub casting by simulation

process using ADSTEFAN casting simulation software. These studies helps to optimize gating system.

VI. CO NCLUSIO NS

In the present work a three dimensional (3-D) component model was developed by CATIA V5 and using

casting simulation software ADSTEFAN to evaluate possible casting defects for sand casting of Wheel Hub.

Notable conclusions from this study are:

To overcome the problems of current gating or riser system, a method based on CAD and simulation

technology is implemented.

By adopting the pressurized gating system, the fluid flow was smooth and air was expelled without any

entrapment inside the mould cavity. Simulation showed that the molten metal was able to fill the mould

within the desired time. Therefore heat distribution was good and no cold shut was observed.

In first iteration improper location of riser and ingates led to formation of shrinkage porosities wh ere in

the final case the height of riser is decreased, diameter of the riser is increased and exothermic sleeves

are used for the wheel hub component casting to achieve directional solidification, which leads to

sound casting.

The final case resulted in reducing the shrinkages and the defect associated with the casting is

eliminated and the sound cast is achieved by the using the exothermic sleeves.

By analyzing simulation results, the optimized riser system is determined.

The yield of the casting is increased by 21.91%.

Shrinkage

Porosity


From the above study it can be concluded that the defect analysis done by simulation help a practice

foundry man to take decision and corrective actions can be taken to eliminate defects with lesser

efforts.

By modifying the design of gating system which includes sprue, runner, gates and rises by trial and

error method using the ADSTEFAN simulation tool, one can able to determine the amount of material

to be used, time required to fill mold cavity and can determine the cost of different man ufacturing

products.

ACKNO WLEDGEMENT

The author’s wishes to thank research paper review committee, Department of Mechanical

Engineering. HOD and Principal of P.D.A. college of Engineering, Gulbarga for their suggestions,

encouragement and support in undertaking the present work. I also express special gratitude to my guide

Professor Bharat S Kodli, Senior Application Engineer Santhosh Kumar A. S, ProSIM R&D Pvt, Ltd, Bangalore

and Chidanand G, Head-Technical skill Development ProSIM R&D Pvt, Ltd, Bangalore for his inspiration,

guidance, constant supervision, direction and discussions in the present work, Last but not the least i would like

to thanks Dr. S B Patil TEQUIP Coordinator PDA college of Engineering.

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Documents

CASTING SIMULATION OF WHEEL HUB USING ADSTEFAN SIMULATION · PDF fileCASTING SIMULATION OF WHEEL HUB USING ADSTEFAN SIMULATION SOFTWARE Keertikumar1, Bharat.S.Kodli2, Santhosh Kumar