external final report (modified)

1

CHAPTER: 1 COMPANY PROFILE

1.1 INTRODUCTION

We are carrying out Project Work in FINE CAST Pvt. Ltd., V.U. Nagar.

Fig. 1.1 Company Logo

It was established in 1973.

The company is ISO 9001: 2008 certified.

It is Grey Cast Iron Foundry Industry.

Contact details: www.finecast.co.in

Its Current Customers are Elecon, Ingersollrand, etc.

1.2 COMPANY PRODUCTS

Frequent products cast by the company include Crank case, Gear case, Housings,

Pulleys, Engine Casings etc.

Few of them are shown in fig. 1.2 (a), (b), (c), (d), (e), (f), (g).

(a) (b) (c) (d)

(e) (f) (g)

Fig. 1.2 Company Products

2

1.3 AVAILABLE FACILITIES

Tilting type Induction Furnaces- two (1000 kg each); Fig. 1.3 (a)

Cupola Furnace; Fig. 1.3 (b)

Tilting type Pouring Ladles-three (having different capacity); Fig. 1.3 (c)

Sand Mixing Muller-three (having different capacity); Fig. 1.3 (d) Conveyor for molding sand

Molding Machines (of different capacity of ramming pressures); Fig. 1.3 (e)

Carbon Equivalent Meter; Fig. 1.3 (f)

Knock out Machine; Fig. 1.3 (g)

Shot blasting Machines

Sand Reclamation unit and bucket type conveyor

Various Grinders in Fettling shop; Fig. 1.3 (h)

Sand Testing Laboratory (Including Sand siever, Sand rammer, Hot plate, Active clay

setup, Compactibility scale, Moisture content tester, Green compressive strength

tester, Permeability tester, Mould & core hardness tester); Fig 1.3.1 (a) to (i)

(a) (b) (c)

(d) (e) (f)

(g) (h)

Fig. 1.3 Molding & Other Equipments

Courtesy of FINE CAST PVT. LTD.

3

(a) (b) (c) (d)

(e) (f) (g)

(h) (i)

Fig. 1.3.1 Sand Testing Equipments

4

CHAPTER: 2 PROBLEM DEFINITION

2.1 INTRODUCTION

Company has Casting coded EP20, which has very high rejection rate. It is shown in

fig. 2.1.

This is because it is hand molded owing to its size.

We are intended to modify their gating and feeding systems so that its rejection rate

may reduce.

It has 240 kg weight. 2 or 3 rejections affect a lot in overall yield and lead to heavy

losses.

2.2 REJECTION RATE

The frequency of the order for EP20 is 15 castings per month.

Monthly Rejection rate of this casting is shown in fig. 2.2.

2.3 DEFINITION

“Design Optimization of Gating System and Casting Simulation for Cast Iron”

Fig. 2.1 EP20 Casting Fig. 2.2 Rejection Rate

Courtesy of FINE CAST PVT. LTD.

0

1

2

3

4

5

6

May '13 June '13 July '13 August '13

Re

ject

ion

Qty

Month

5

CHAPTER: 3 METHODOLOGY

1. Study of Defects in the cast parts

2. Analyzing probable causes of frequently occurring defects

3. Analyzing rejection rates due to defects for casting

4. Review of Literature for Casting Simulation

5. Solid Modeling of casting using Pro-E

6. Manual Gating system and Riser Designs for casting

7. Study of the casting simulation software

8. Solidification Simulation for Proposed Method & its Optimization

9. Comment on other frequently occurring defects

6

CHAPTER: 4 LITERATURE REVIEW

Sr.

No.

Author Title Conclusion/Abstract Journal

1 K.D.

Carlson,

R.A.

Hardin,

Shouzhu Ou

& C.

Beckermann

Development

of new feeding

distance rules

using casting

simulation:

Part 1.

Methodology

- Developed a methodology to relate

measured shrinkage porosity levels

in steel castings to predictions

from casting simulation, to

determine feeding distances.

- Experimental shrinkage level is

expressed as ASTM shrinkage X-

ray level.

- Predicted value for this is expressed

in terms of Niyama criterion.

Metallurgical

and materials

transactions B;

vol 33 B,

October 2002-

731

2 K.D.

Carlson,

R.A.

Hardin,

Shouzhu Ou

& C.

Beckermann

Development

of new feeding

distance rules

using casting

simulation:

Part 2. The

new rules

- Developed the rules to produce

radiographically sound castings.

- Rules for riser zone length, end

zone length, end effect feeding

distance and lateral feeding

distance for top risers, and feeding

distance for side risers are

developed.

- Extension of these rules for the

provision of feed-aids such as

chills.

Metallurgical

and materials

transactions B;

vol 33 B,

October 2002-

741

3 B. Ravi,

R.C. Creese

& D.

Ramesh

Design for

casting- A new

paradigm for

preventing

potential

problems

- Often, product design causes severe

problems at the casting stage, in

terms of defects and difficulties in

molding.

- Significant design modifications at

this stage lead to heavy losses.

- Simulation provides the way out by

virtual trials during the very design

stage of product.

Transactions

of the

American

Foundry

Society, 107,

1999

4 K. Singh,

P.K. Reddy,

D. Joshi, K.

Subburaj &

B. Ravi

3D junctions in

castings:

Simulation

based DFM

Analysis and

Guidelines

- Casting defects, which can’t be

eliminated by changes in tooling

and process parameters, can be

attributed to poor design of the part

wrt manufacturability.

- These defects can be predicted by

simulation, and corrected by minor

changes in part design.

- Junctions are regions of high

thermal concentration so changes

must be made in them by

referring result of simulation.

INAE-

ICAMT 2008,

Feb. 6-8, 2008

7

5 B.G.

Thomas

Issues in

thermal-

mechanical

modeling of

casting

processes

- Stress modeling begins with a

coupled, transient heat transfer

analysis, including solidification,

shrinkage dependent interfacial heat

transfer, & fluid flow effects.

- Numerical calculation of stress-strain

that arises during solidification is

important to predict surface shape

and cracking problems.

Iron & Steel

inst. Of

Japan

International,

Vol.35, No.

6,

1995,pp.737-

743

6 Mark Jolly Casting

Simulation:

How well do

reality and

virtual casting

match? State of

the art review

- The interface heat transfer co-

efficient is probably the most

fudged part of casting modeling.

- Defects must be represented

graphically so that anyone can

easily interpret that.

Int. J. Cast

Metals Res.,

2002, 14,

303-313

7 Z. Guo, N.

Saunders,

A.P.

Miodownik

& J.-Ph.

Schille

Modeling of

materials

properties and

behavior

critical to

casting

simulation

- Development and calibration of

software used to calculate thermo-

physical properties of the mold-

metal and interface.

- These properties must be known

accurately as they are needed in

solidification simulation as inputs.

- These properties alter substantially

even by small change in

composition.

Materials

science and

engineering

A 413-414

(2005) 465-

469

8 Dr. B. Ravi Casting

Simulation and

Optimization:

Benefits,

Bottlenecks,

and best

Practices

- Casting simulation can predict

location of internal defects and

visualize mold filling, solidification

and cooling.

- Casting simulation can enhance the

productivity and success of method

engineer, but can’t replace him.

Tech. paper

for Indian

Foundry

journal Jan.

2008 Special

issue

9 Dr. B. Ravi,

D. Joshi &

K. Singh

Part, Tooling

and method

optimization

driven by

Castability

analysis and

cost model

- Evaluation of the simulation result

using three quality indices:

moldability, fillability & feedablity.

- This evaluation leads to modified

part, tooling & method design and

in turn reduces the cost

substantially.

1. Moldability- Deviation from the

designed shape

2. Fillability- Effects of mold filling

characteristics

3. Feedability- Effects of solidification

characteristics

68th

world

foundry

congress,

Chennai, 7-

10 feb. 2008

8

10 T.R.

Vijayaram,

S. Sulaiman,

A.M.S.

Hamouda &

M.H.M.

Ahmad

Numerical

simulation of

casting

solidification

in permanent

metallic molds

- Solidification simulation of casting

can be performed by FDM, FEM,

FVM and BEM.

- It can identify defective location in

the casting generated time-

temperature contours.

Journal of

materials

processing

technology

178 (2006) 29-

33

11 Dr. B. Ravi Casting

simulation-

Best practices

- Casting simulation helps in (a)

quality or yield improvement of

existing castings and (b) rapid

development of new castings.

- Input 3d part model must be as-

cast part not the machined part (in

STL format).

- As curved surface is approximated

by a no. of triangles, even a small

fillet can lead to large increase in

file size.

- So, small features can be safely

removed from CAD model,

without much affecting the result,

to reduce the computation time.

Trans. Of 58th

IFC,

Ahmedabad

(2010)

12 B. Ravi &

M.N.

Srinivasan

Feature

recognition

and analysis

for molded

components

- Methods for obtaining the solid

corresponding to the feature, based

solely on BRep, have been

developed for the design of

pattern, mold, core & core-box.

13 Dr. B. Ravi Computer

aided casting

method design,

simulation and

optimization

- Latest version of AUTOCAST is

able to create entire core model &

feeder model automatically.

- More feeders can be created by

specifying their positions. Feed-

aids can also be applied.

- Gating system can be created after

specifying the positions of gates on

the part. Sprue location is to be

specified and runners are created

automatically.

- So, design, simulation &

optimization of method layout is

easily carried out using simulation

software.

Inst. Of Indian

Foundry men

(Indore

chapter), 13

march 2008

9

14 V.M.

Gopinath,

A.

Venkatesan

& A.

Rajadurai

Simulation of

casting soli.

and its grain

structure

prediction

using FEM

- In addition to temperature

distribution, grain structure of the

casting can be predicted by

extending the program to

calculate G (temp. gradient), R

(interface velo.) and dT/dt (soli.

rate).

Journal of

materials

processing

technology

168 (2005) 10-

15

15 B. Ravi &

M.N.

Srinivasan

Casting

solidification

analysis by

modulus vector

method

- Discovered a new geometry driven

method called Modulus Vector

Method for identifying hot spots &

simulations of feeding paths.

- Simulation based on this method is

less sensitive to inaccurate values

of interface heat transfer co-

efficient value.

Int. J. Cast

metals Res.

1996, 9,1-7

16 K.S. Chan,

K.

Pericleous

& M. Cross

Numerical

simulation of

flows

encountered

during mold

filling

- Described a model to simulate

flows & interface activity during

the filling of 3-d casting molds.

- The equations governing the

complex physical phenomenon of

mold filling are Navier- Stokes

equations, Continuity equation

and turbulent viscosity equation.

Appl. Math.

Modeling,

1991, vol. 15,

nov./dec.

10

CHAPTER: 5 CASTING PROCESS

5.1 INTRODUCTION

It is the process of manufacturing in which molten metal is poured in the cavity,

known as mold cavity, so that solidified metal takes the shape of the cavity. The

solidified metal is called Casting and the process is called Casting Process.

Mold cavity is prepared by patterns. It is always larger in size than the actual casting.

Fig. 5.1 (a) shows various terms related to casting process.

Fig. 5.1 (a) Terms Related To Casting Process

Classification of Casting Processes is shown in fig. 5.1 (b).

Fig. 5.1 (b) Classification of Casting Processes

11

5.2 CASTING PROCESS CARRIED OUT AT FINE CAST

1. Melting Practice:

As Fine Cast is producing Grey iron castings, they are equipped with a cupola and two

tilting type induction furnaces (of 1 ton melting capacity). In usual running, one induction

furnace is operated and other is prepared in terms of refractory lining. Induction furnace

is better than cupola in terms of melting time and composition control of the desired melt.

Typical charge calculation (of 1 ton) include 500 kg of bead scrap, 130 kg of steel scrap,

350 kg of return riser, 180 kg of pig iron, 8 kg of silicon, 9 kg of carbon, 800 gm of

manganese and 600 gm of INOCULATION (Graphite and Silicon- to improve

machinability and reduce chances of defects in casting). Before transferring the molten

metal into pouring ladle at 15000c, sample melt is poured into Carbon Equivalent Meter

cup, in order to check Carbon and Silicon content. It must be within prescribed limits.

2. Sand Preparation: Mainly Kheda and Jhagadiya sands are used as silica sand. For the cores, oil is added as

binders and mulled properly to obtain thorough and homogeneous mixture called core

sand. Cores are made manually using this sand and are allowed to set for 8 hours.

Generally, cores required tomorrow are made a day before. Previously, they were using

Molasses as binder; there core backing i.e. heating was necessary. Molding sand has

totally different composition of ingredients as compared to core sand. It uses reclaimed

sand and for one lot 15 kg of bentonite powder (to improve GCS), 1 kg of coal dust

powder (to improve gas formation) and 20 liters of water are added and the mixture is

mulled. The molding sand is conveyed to the molding machines via conveyor-belt

system.

3. Mold Making & Core setting:

Here, molding sand is rammed either manually or by machines into the molding boxes

depending upon the sizes of the castings. Machine rammers are using vibrations and

squeezing action for this purpose. Pin lifting mechanism is incorporated in the machines.

Sometimes, mold heating is also done to remove excess moisture from it. Generally, cope

part is molded with gating and riser system and venting is also provided. Cores and molds

of larger castings are painted to reduce chances of defects in castings. During this phase,

core is assembled with the molding boxes and mold is made available ready for pouring.

Mold and core hardness are frequently checked during the operation.

4. Pouring:

The ready molds are transferred to the pouring area and molten metal is poured in it from

the tilting type ladle which runs with the help of overhead crane. Pouring rate is

controlled by the operator himself. Pouring ladle also has refractory brick lining to

minimize heat losses. After completely filling the mold, riser and sprue openings are

covered with the sand to minimize heat losses.

5. Fettling & Knockout: After the solidification of the casting, the mold and core is broken at knockout machine

with the help of vibrations. After this the sprue, runners and risers are separated out of the

casting and the sand of the broken mold is sent to the reclamation unit. In reclamation,

12

metallic particles and other impurities are separated out from the sand and the sand is

made useful again. Casting is then shot blasted so that clean metal surface exposes. Any

indication of defect appears at this stage. Then, casting is sent for grinding and other

operations either of quality check or of machining.

6. Sand Testing: The most important phase of casting is testing the properties of the molding and core

sands to ensure desired properties in them. Sand samples are tested frequently in a day

i.e. 8-10 times a day. Sand is tested for compactibility, permeability, green compressive

strength, active clay content, moisture content, etc. Though it seems very simple but any

wrong decision during sand testing leads to major failure in the output, as sand is the

heart of sand casting processes. Fig. 5.2 (b) shows all these steps as flow diagram.

Fig. 5.2 (a) Steps Involved in Casting Process

7. Spectroscopy:

The Company has facility of checking various compositional elements of the cast metal.

The equipment used for this purpose is called SPECTRO METER. It uses spark produced

by high pressure Argon gas for the checking. Within 2-3 minutes, proportion of different

21 elements is known. Spectometer is available at HIMSONS CAST premises.

Spectrometer is shown in fig. 5.2 (b).

Fig. 5.2 (b) Spectrometer

13

CHAPTER: 6 CASTING DEFECTS

6.1 TYPES OF DEFECTS

Fig. 6.1 shows Classification of Casting Defects based on Conformance Criteria.

Fig. 6.1 Classification of Casting Defects based on Conformance Criteria

Courtesy of efoundry.iitb.ac.in

6.2 VARIOUS CASTING DEFECTS & THEIR CAUSES

1. Flash: This defect forms thin protrusion of metal at the parting line of mold on the castings.

This is due to improper closure of the mold boxes i.e. insufficient clamping force on

the cope and drag. This defect always increases rework on the castings. It is shown in

fig. 6.2 (a).

2. Mismatch: Due to incorrect closure of the mold boxes, another defect appears called mismatch.

Here either cope or drag shifts along parting line so casting is rejected. Sometimes

shifting of the patterns during molding causes this defect. It is shown in fig. 6.2 (b).

3. Cold shut: It is caused when two streams of metal which are too cold meet but do not fuse

together. The causes of this defect are incorrect design of casting, gating system and

riser as well as incorrect temperature of the melt. Generally, this defect can be

inspected visually as it happens on the surface of the castings. It is shown in fig. 6.2

(c).

4. Misrun: If the mold cavity is partially filled due to rapid solidification at thinner sections,

defect called misrun takes place. If the casting has abrupt thickness changes or design

of gating and risering systems are incorrect then this defect is predominant. It is

shown in fig. 6.2 (d).

14

5. Inclusions:

Inclusions are any foreign materials present in the cast metal. These may be in the

form of oxides, slag, dirt, sand or nails. Common sources of these inclusions are

impurities with the molten metal, sand and dirt from the mold not properly cleaned,

break away sand from the mold, core or gating system, gas from the metal and

foreign items picked on the mold cavity while handling. Inclusions are reduced by

using correct grade of molding sand and proper ramming of it.

6. Blow holes:

It is often observed and its causes are the entrapment of gases and air within the

solidifying casting. Probable causes to this are poor mold venting, excessive binder in

the core and mold, less permeable molding sand (fine sand), fast pouring rate,

incorrect gating system design (turbulence), etc. It is located either internally or

beneath the surface (subsurface), so it can be detected by RADIOGRAPHY in which

it appears as DARK SPOT. It is shown in fig. 6.2 (e).

7. Gas porosity:

This also occurs due to gas entrapment. But the difference between Blow holes & Gas

porosity lies within their size. Gas porosity is small in size and is seen in a group of

small cavities internally, whereas blow holes are relatively larger in size. Causes for

this defect are same as that for blow holes. It can be detected by RADIOGRAPHY in

which it appears as cluster. It is shown in fig. 6.2 (f).

8. Shrinkage porosity:

It is the most frequently occurring defect. The reason behind this is the solidification

shrinkage that takes place during the solidification process. However, it can be

eliminated by proper design and placement of riser or feeder. More complex castings

need more than one feeder at the locations where hot spots are generated. Size of

shrinkage porosity is large relatively so it is often called shrinkage cavity. Distinction

between shrinkage and gas porosity is that the shrinkage porosity has rough surface

while gas porosity has smooth surface. This defect also occurs internally, generally

near the hot spot. So, it can be detected by RADIOGRAPHY. Shrinkage Cavity is

shown in fig. 6.2 (g).

9. Shrinkage Related Other Defects:

If shrinkage occurs at the centre line of the section, then it is centre line shrinkage.

If shrinkage occurs at the corner of the casting, then it is corner shrinkage.

Pipe is the only defect which is DESIRABLE. It should occur in the feeders to

ensure that feeder has successfully performed its function. It is shown in fig. 6.2 (h).

10. Hot tears or Cold Cracks:

Hot tears are irregular internal or external cracks occurring immediately after the

metals have solidified. Hot tears occur on poorly designed castings having abrupt

section changes or having no proper fillets or corner radii, wrongly placed chills. Hot

tears are also caused due to poor collapsibility of the cores. If the core does not

collapse when the casting is contracting over it, stress will be set up in the casting

15

which leads to its failure. If sufficient time is not given to the casting for solidifying

and if one starts shake out operation then also chances of having hot tears increase.

Hot tears can be reduced by improved design of casting, proper directional

solidification, uniform cooling rates, correct shakeout temperature and control of

mold hardness. It is shown in fig. 6.2 (i).

11. Distortion:

This defect occurs especially when very long thin castings are cast. It is shown in fig.

6.2 (j).

(a) (b) (c)

(d) (e) (f)

(g) (h)

16

(i)

(j)

Fig. 6.2 Various Casting Defects

17

CHAPTER: 7 NEED OF GATING & FEEDING SYSTEMS

7.1 INTRODUCTION TO GATING SYSTEM

It is a passageway for molten metal.

It is needed for Proper filling of mold cavity to ensure good quality casting.

7.2 ELEMENTS OF GATING SYSTEM

All the elements of Gating System can be easily visualize from the fig. 7.2.

It comprises of Pouring Cup or Pouring Basin, Sprue, Sprue Well, Runners, Ingates

and Runner Extensions.

Fig. 7.2 Elements of Gating System

7.3 NEED OF GATING SYSTEM

To regulate the flow of molten metal into mold cavity

To ensure the complete filling of mold cavity before freezing

To minimize the turbulent flow which can cause absorption of gasses, oxidation of

the metal and erosion of mold surfaces

To promote temperature gradients favorable for proper directional solidification

To incorporate traps for separating the inclusions from the molten metal

7.4 INTRODUCTION & NEED OF FEEDING SYSTEM

It includes risers or feeders, feed-aids & neck.

It is considered separately because it has different function than Gating system.

Risers are added reservoirs designed to feed liquid metal to the solidifying casting as

a means for compensating for solidification shrinkage.

This is only possible if riser solidifies at last.

Riser is located near the section that will solidify (i.e. at the thickest section) at last in

order to promote directional solidification.

18

In other words, feeder shifts the HOT SPOT from the casting into itself.

Function of Riser is shown in fig. 7.4.

Without Riser With Riser

Fig. 7.4 Function of Riser


19

CHAPTER: 8 DESIGN OF GATING & FEEDING SYSTEMS

8.1 TYPES OF GATING SYSTEM

According to Orientation

Horizontal & Vertical; fig. 8.1 (a) to (e)

According to Position

Top, Bottom & Parting Line; fig. 8.1 (f), (g), (h)

According to Number of Gates

Single Gate & Multiple Gates

According to Gating Ratio

Pressurized & Non-Pressurized

(a) (b)

(c) (d) (e)

(f) (g) (h)

Fig. 8.1 Types of Gating Systems

20

8.2 GATING SYSTEM DESIGN

1. Pouring Cup & Pouring Basin

Any one of these is necessary so as to direct the flow of the molten metal from

pouring ladle to the mold cavity.

Pouring Basin, in addition to this, provides better slag trap and smooth cavity

filling properties i.e. reduces turbulence and vortexing at the sprue entrance.

Pouring cup is funnel shaped cup at the top of the sprue.

2. Sprue

It is tapered (and not parallel which causes higher mold erosion) with its bigger

end at the top to receive the liquid metal. The smaller end is connected to the

runner.

It will thus allow continuous feeding of molten metal into mold cavity.

Round sprue has minimum surface exposed to cooling and offers lowest

resistance to flow of metal.

There is less turbulence in a rectangular sprue.

3. Gate

It is a channel which connects runner with the mold cavity. Runner connects sprue

base with the gates.

Molten metal enters the mold cavity through gates.

It should feed liquid metal to the casting at a rate consistent with rate of

solidification.

A small gate is used for casting which solidifies slowly and vice-versa. More than

one gate may be used to feed a fast freezing casting.

A gate should not have sharp edges.

There are varieties of Top, Bottom & Parting line gates which are used in

practice.

All these elements of gating system are shown in fig. 8.2 (a).

Fig. 8.2 (a) Elements of Gating System

21

4. Governing Equations

First equation is Reynold’s equation which gives the value of a dimensionless

number which indicates whether flow of fluid is turbulent or not. Generally,

turbulent flow occurs if the value of Reynold’s number exceeds the value 4000.

𝑅𝑒 =𝜌𝑉𝐷

𝜇

Continuity equation of fluids is very important as it is used for designing the

sprue. This law holds good for only those ducts, tubes or channels which run full.

𝑄 = 𝐴1𝑉1 = 𝐴2𝑉2

Bernoulli’s equation is also very useful in the gating system design. This is

because it is used to find out the velocity of the molten metal at sprue base, given

the height of the sprue.

𝑉12

2𝑔+ 𝑕1 +

𝑃1

𝜌𝑔= 𝑉2

2

2𝑔+ 𝑕2 +

𝑃2

𝜌𝑔

Note that this equation is written neglecting the loss of head during the flow.

By manipulating this equation, we get

𝑉2 = 2𝑔𝑕𝑠

Another important equation is Darcy- Weisbach equation. It is basically an

equation of loss of head during fluid flow through pipes due to friction.

𝑕𝑓 = 𝑓𝐿𝑉2

2𝑔𝐷

Choke: It is that part of gating system which possesses smallest cross- sectional

area. In pressurized gating system, gate serves as choke. So, very high velocity

will lead to excessive mold erosion and turbulence in the fluid flow. Area of the Choke is calculated by using modified form of Bernoulli’s equation.

𝐶𝐴 = 𝑊

𝑐𝜌𝑡 2𝑔𝐻

22

Pouring Time: Selection of optimum pouring time is major problem in foundries.

Some empirical formulas are setup to find the pouring time for a particular size &

shape of the casting. Here, only Grey Cast Iron is taken into consideration.

For Castings weighing more than 1000 lbs

𝑃𝑜𝑢𝑟𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 = 𝐾 0.95 + 𝑇

0.853 𝑤

3 𝑠𝑒𝑐𝑜𝑛𝑑𝑠

For Castings weighing less than 1000 lbs

𝑃𝑜𝑢𝑟𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 = 𝐾 0.95 + 𝑇

0.853 𝑤 𝑠𝑒𝑐𝑜𝑛𝑑𝑠

Where K= Fluidity factor

= Fluidity of specific iron

40

8.3 FEEDING SYSTEM

Feeding system includes Risers or Feeders, Feed-aids & Neck connection.

Risers or Feeders are used to compensate the liquid metal for Liquid to Solid

shrinkage.

It is extremely useful to avoid the hot spots and hence shrinkage defects in the

castings.

Always feeders must solidify at last. This is only possible if Modulus of the feeder is

larger than Modulus of the castings.

Feed-aids include Sleeves, Chills, Padding, Fins, Exothermic materials, etc.

These are extensively used in foundries as they improve the yield by improving the

effectiveness of the risers. Fig. 8.3 (a) & (b) shows Chills & Sleeves respectively.

Neck is the connection between the Riser and Casting. Typical figure for this is

shown as fig. 8.3 (c).

(a) Chills (b) Sleeves


23

(c) Various Neck Connections

Fig. 8.3 Feed aids & Neck Connections

8.4 METHODS OF RISER DESIGN

A. Chvorinov’s Rule:

It states that freezing time is proportional to (V/A)2. It means if metal in riser has

to remain liquid for a longer time, V/A should be large or A/V should be small.

According to this rule, riser should be cylindrical (round) rather than square or

rectangular of equivalent mass.

Spherical risers are the best by this criteria but due to difficulties in molding,

feeding and fettling, they are not practicable.

t freezing or t solidification = k (Volume/Surface Area)2

According to this rule,

ts sphere > ts cylinder > ts bar > ts plate

B. Modulus Method:

Modulus is nothing but ratio of Volume and Surface area.

Empirically, M feeder ≥ 1.2 M casting

After this, appropriate h/d ratio is assumed & dimensions of riser are calculated.

C. Caine’s Method:

It is based on an experimentally determined hyperbolic relationship between

relative volumes and relative solidification rates of riser and casting to produce

shrinkage free castings.

24

Reason for taking Surface area to Volume ratio is that, surface area represents the

heat dissipation and the volume (within which mass of liquid is present), represents

quantity of heat.

Relative freezing time

Quantity of metal required

for compensating shrinkage

So, Caine’s Equation:

Where

a= freezing chara. Constant

b= liquid- solid shrinkage

c= relative freezing rate of

riser & casting

Caine’s curve is basically a hyperbola having specific values of constants a, b and

c as discussed above. It is shown in fig. 8.4 (a).

Fig. 8.4 (a) Caine’s Curve

01-x

ratio freezing xwhere

1,or x 1

V

A

V

A

V

A

V

A

riser

casting

risercasting

0

,V

V

c

r

b)(y

ion ratios contractwhere, y i

bb or y

cby

ax

abyx

byx

)(

))(1(

0))(1(

25

D. NRL (Naval Research Laboratory) Method:

A further and simplified development of the Caine’s approach was that of Bishop,

who used the concept of a shape factor to replace the surface area to volume ratio

used in the earlier relationship.

The shape factor

where L, W and T are the length, breadth and thickness of the section concerned.

General Procedure:

I. Calculate shape factor for critical section.

II. Derive the value of V riser/ V casting from the NRL graph as shown in fig. 8.4

(b).

III. With known V casting, V riser can be found out.

IV. Various alternative h/d combinations are selected.

Fig. 8.4 (b) NRL Graph

T

WLS

26

CHAPTER: 9 WORK FLOW AS PER METHODOLOGY

9.1 Study of Casting Defects in Cast Parts:

Detailed study of various casting defects is completed (As described in Chapter 6).

9.2 Analyzing Probable Causes of Frequently Occurring Defects:

Detailed study of probable causes of various casting defects is completed (As

described in Chapter 6).

9.3 Analyzing Rejection Rates Due to Defects for Casting:

Monthly rejection of concerned casting, EP20, is shown in Chapter 2 (Fig. 2.1 & 2.2).

Contribution of various defects to rejection rate of EP20 is shown in fig. 9.3.

Fig. 9.3 Analysis of Rejection Rate

Mold & Core surfaces of EP20 casting are painted with thinner.

Because of this, surface of the castings become smooth and chances of getting Blow

holes also reduces.

From the fig. 9.3, it is clear that Shrinkage is major problem.

Frequency of rejection due to cold shut is high because casting has very intricate

shape & may be due to improper gating & feeding system design.

9.4 Solid Modeling of Casting Using Pro-E:

Human Can’t Survive Without O2 , likewise any Casting Simulation Software Can’t

Proceed Without Solid Model of the Casting.

Also, the file format of the solid model is universal which is .STL (Fig. 9.4.1).

0

1

2

May '13 June '13 July '13 August '13

Qty

Rej

ecte

d

Month

Shrinkage

Cold Shut

Crack

Mismatch

27

Some of the software need solid models along with Gating & Feeding systems & core

assembled mold box modeled with it as input.

Few advanced software help solving this difficulty. They assist in designing Gating &

Feeding Systems based on some criteria. Also they automatically recognize features

to create core automatically.

Another compulsion is that we must use 3D solid model & not either wire frame

model or surface model.

This is because in wire frame or surface model mass and volumetric properties of cast

metal cannot be known.

Any casting has basically Three types of features:

1. Base Features:

They define overall shape of casting.

Its shape can be rectangular block, cylinder, sphere, spiral, L bracket, etc.

2. Local Feature:

It can be Depression or Protrusion on the base feature.

Ex: Hole, Pocket, Slot, Boss, Rib, etc.

3. Connecting or Modifying Feature:

They are used to connect two or more features.

Ex: Taper, Chamfer, Fillet, Draft, etc.

Any Casting can be modeled by using various features, as mentioned above, available

in various modeling software.

There are varieties of software available in market for solid modeling but we adopted

Pro-E.

PRO-E is basically Parametric software.

So, using Pro-E 5.0, we have modeled EP20 casting from the photographs available

to us. Detailed drawing was not given to us because of privacy policy.

Fig. 9.4 shows the development of solid model of EP20 casting in different phases.

Fig. 9.4 (a) Phase 1

28

Fig. 9.4 (b) Phase 2

Fig. 9.4 (c) Phase 3

29

Fig. 9.4 (d) Phase 4

Fig. 9.4 Various Phases of Solid Modeling

Fig. 9.4.1 STL file of EP20 part

30

9.5 Manual Gating System & Riser Designs for Casting:

Methods of designing various elements of Gating and Feeding Systems are very well

understood and are explained in Chapter 8.

GATING SYSTEM:

Essential Input Parameters

Density of Gray Cast Iron, ρ = 7.1 gm/cm3

Average section thickness, T = 15 mm

Fluidity of Gray Cast Iron = 30 inch

Weight of casting, W = 240 kg

Nozzle coefficient, c = 0.9

Gating Ratio = 1:4:4

Effective Head, H = 462.5 mm

Cross section of runner and ingate = Rectangular

Ratio of height to width for runner = 1:2

Ratio of height to width for ingate = 1:2

No. of ingates = 4

Calculated Parameters (Refer page 21 & 22, chapter 8 for governing equations)

Pouring time, t = 28.328 seconds

Choke area, A = 440.138 mm2

Diameter at top of the pouring cup = 150 mm

Diameter at top of the downsprue = 90 mm

Diameter at sprue base = 75 mm

Area of sprue base = 4417.86 mm2

Area of runner and gates = 1104.47 mm2

Dimensions of runner: height = 23.5 mm & width = 47 mm

Area of one gate = 276.12 mm2

Dimensions of gate: height = 11.75 mm & width = 23.5 mm

Various elements of gating system are shown in the form of 3d models in fig.

9.5.1. Note that these models are based on designed values.

(a) (b) (c)

Fig. 9.5.1 Models of Various Elements of Gating System

31

FEEDING SYSTEM:

Essential Input Parameters

Volume of casting, V = 33.80 X 106 mm

3

Surface area of casting, A = 3.45 X 106 mm

2

Existing method of Feeding at Fine Cast

No. of Feeders = 10

Modulus of casting, MC = 9.8 or approx. 10

Modulus of Riser, MR = 1.25MC = 12.5

Cross section of riser used in existing method is shown in fig. 9.5.2.

Fig. 9.5.2 Cross section of existing riser

Proposed method

No. of feeders = 2 or 4

Cross section of riser = Cylindrical

May or may not have Neck

General configuration of the riser for sign convension is as per fig. 9.5.3.

Fig. 9.5.3 Sign convention for proposed riser geometry

32

9.6 Study of the Casting Simulation Software:

Simulation is the process of imitating a real phenomenon using a set of mathematical

equations implemented in a computer program. It is used to Predict or Prevent the

process growth.

Metal casting is subject to an almost infinite number of influences. A few major

factors related to casting geometry, material, and process, are listed below:

1. Casting Geometry:

Part features, including convex regions (external corners), concave regions

(internal corners), cored holes, pockets, bosses, ribs, and various junctions (2D

and 3D), all of which affect the flow and solidification of metal.

Layout in mould, including number of cavities, and their relative location (inter-

cavity gap and cavity-to-wall gap), which affect the amount of heat absorbed by

the mould.

Feed-aids, including number, shape, size and location of insulating sleeves and

covers, chills (external or internal), and padding, which affect the rate of heat

transfer from the relevant portion of the mould.

2. Casting material:

Thermo-physical properties of the metal/alloy, including its density, specific heat,

thermal conductivity, latent heat, volumetric contraction during solidification,

coefficient of linear expansion, viscosity and surface tension.

Thermo-physical properties of mold, core and feed-aid materials, including

density, specific heat, thermal conductivity, coefficient of linear expansion.

Changes in properties with composition and temperature, relevant transformations

(grain shape, structure, distribution), and resultant mechanical properties.

3. Process: Turbulent flow of molten metal in the mould with splashing, stream separation

and rejoining, mould erosion, gas generation and escape through venting, coupled

with heat transfer leading to reduced fluidity. Casting solidification with multiple modes of heat transfer (conduction,

convection and radiation) involving non-uniform transient heat transfer rate from

metal to mould, including latent heat liberation and moving liquid-solid boundary. Solid state cooling with changes in mould shape and dimensions, leading to

residual stresses and/or deformation in cast part, and different grain structures

affecting the final properties in different regions. Process parameters including actual composition of metal/alloy, mould size,

mould compaction, mould coating, mould temperature, pouring temperature and

rate, mould cooling, shake out.

It is no surprise that a complete and physically accurate simulation of metal casting

process is very difficult

33

The key to developing a practically useful simulation program is to determine which

the most important factors are. Some of the well-known casting simulation programs currently available to foundry

engineers are AutoCAST, CastCAE, Castflow, MAGMAsoft, MAVIS, Procast,

Sutcast, SOLIDcast, etc. Use of simulation software may result in Quality enhancement, Yield improvement or

Rapid development of newer castings.

Factors Affecting Accuracy of Simulation:

1. Assumptions of mathematical model & model definition

2. Discretization or Pre-processing

3. Approximations during analysis (IHTC, material prop.)

4. Post-processing or Interpretation

Simulation Process Sequence:

1. Formulate the physics of process in PDE form

2. Discretize the geometry(FEM, FDM, FVM)

3. Write equations for all the nodes & generate matrices

4. Apply boundary conditions (IHTC, Feed aids, etc)

5. Solve the matrices

6. Present the results calculated

Disadvantages of Numerical Methods:

− In most of the software, numerical methods like FEM, FDM, FVM, BEM have

been used.

− Here, discretization is done & unsteady state heat transfer equations are applied

on them periodically.

− Hence, this method is time consuming. Also, input values mean a lot to this

method.

− This has been rectified by incorporating the geometry based method called MVM

(Modulus Vector Method).

Comparison between various methods:

− In general, FEM is preferred as it allows a wider choice of element shapes and

better accuracy. It requires manual effort to correctly generate element mesh.

− FDM & FVM based simulation programs are faster and easier to execute but

elements are cubic & brick type only.

34

MVM (Modulus Vector Method):

− Method is also called GVM (Gradient Vector Method) or VEM (Vector Element

Method).

− It will show the location of hot spot in the casting without much computation.

− This method is better understood from the fig. 9.6 (a) & (b).

(a) (b)

Fig. 9.6 Modulus Vector Method


− A unit sphere is constructed around the point Pi and the surface of sphere is

divided into n number of equal regular polygons.

− Each polygon is defined by a set of bounding points Pijk, lying on the sphere.

− Let, Cijk be the centroid of the above polygon, and β be the solid angle subtended

by the polygon at the centre of the sphere Pi.

− Rays starting from Pi and passing through Pijk are projected to compute their

intersections P’ijk with the surface of the casting model.

− Each set of these points are connected to Pi to form pyramidal segments for each

elements.

− The modulus vector for any segment is defined as

Where V and A are volume and area of base of any pyramidal segment

respectively.

− In case of 2D geometry, the equation reduces to

Where A and S are Area and length of sector of any triangular segment

respectively.

− The direction and relative magnitude of the largest temperature gradient at Pi is

given by the resultant of the modulus vector for all the segments.

35

− The direction of the largest thermal gradient at any point inside the casting will

show the path of molten metal feeding and hence the location of HOT SPOT.

Capabilities of Simulation Software:

− Solidification Simulation

− Flow Simulation (Marker & Cell method, Volume of fluid method)

− Coupled Simulation (Thermal-Flow-Stress Simulation, Thermal-Flow-

Microstructure Simulation)

Critical Inputs for Solidification Simulation:

− Part & Tooling Geometry

− Material properties

− Mesh type & size

− Boundary conditions

− Metallurgical models (Shrinkage, microstructure)

Critical Inputs for Mold Filling Simulation:

Same as above except that instead of metallurgical models, we have to feed Flow

models (Cold shut, air/gas entrapment, inclusion).

Examples of simulation by Software:

Solidification Simulation : Fig. 9.6.1 (a), (b) & (c)

(a) Hot spot (b) Temperature Distribution (c) Feed paths

Fig. 9.6.1 Examples of Solidification Simulation


36

Mold Filling and Coupled Simulation : Fig. 9.6.2 (a), (b) & (c)

(a) Fill Time (b) Velocity (c) Solidification Time

Fig. 9.6.2 Examples of Mold Filling & Coupled Simulation


Trial Performed on the Online Software Resource (E-foundry):

(a) (b) (c)

Fig. 9.6.3 Trials for Result Interpretation


9.7 Solidification Simulation for Proposed Method & its Optimization:

Need of changing the existing method for EP20 can be visualized from the results of

simulation of that existing method.

− Fig. 9.7.1 (Page 37) shows the complete assembly of EP20 casting along with

existing method used in Fine Cast.

− Temperature scale used for the results is as per fig. 9.7 ().

− After simulating this whole assembly, the result obtained is as shown in fig. 9.7.2

(Page 37).

AMBIENT 12000C

Fig. 9.7 Temperature scale

37

Fig. 9.7.1 Existing method assembly for EP20

Fig. 9.7.2 Simulation result of existing method for EP20

38

− So, it can be concluded that the risers put on the casting do not serve their

function of moving the hot spot from casting within them.

− Instead, there are chances of having fast freezing of risers themselves leading to

major defects in solidified casting.

As stated earlier, modified method has cylindrical risers with or without neck

provision. (Refer fig. 9.5.3)

For the purpose of optimizing the method in terms of chances of defects and casting

yield, large numbers of iterations are performed using simulation.

Firstly, location/s of hot spot/s is/are found out by performing simulation on the

model of the part without gating and feeding systems. The outcome to this is shown

in fig. 9.7.3.

Fig. 9.7.3 Simulation result of EP20 part model (Without Gating & Risers)

The temperature distribution shown in every result can be interpreted in the context of

fig. 9.7 (page 36).

So, there are two large hot spots at two short side ends and small hot spots near the

hole features.

Iterations can be performed by keeping these locations in mind and by varying the

dimensions of the risers.

Note that the Gating system is chosen which is the existing only. No change in Gating

system is incorporated as solidification simulation does not count for that.

The simulation is performed by considering Fine mesh size of molding sand.

39

1. First modified method includes two no. of risers, both having d1= 50 mm, h1= 250

mm (Refer fig. 9.5.3, page 31) and no neck connection. The risers are placed above

two large hot spots. The simulation results, fig. 9.7.4, clearly show no sign of

improvement in terms of shifting of hot spots.

Fig. 9.7.4 Iteration-1 result

2. Second modified method includes two no. of risers, both having d1= 60 mm, h1=

250 mm (Refer fig. 9.5.3, page 31) and no neck connection. The risers are placed

above two large hot spots. Fig. 9.7.5 (page 40) shows that there is no significant

improvement even in this method.

3. Third modification includes two no. of risers, both having d1= 100 mm, h1= 220 mm

and have neck connection with d2= 60 mm and h2= 30 mm (Refer fig. 9.5.3, page 31).

The risers are placed above two large hot spots. Fig. 9.7.6 (page 40) shows that there

is some degree of improvement in this method.

4. Fourth modification incorporates four no. of risers; two of which have d1= 120 mm

and h1= 220 mm, placed above large hot spots, both having neck connection with d2=

60 mm and h2= 30 mm (Refer fig. 9.5.3, page 31), also there is fillet of 10 mm at

neck-riser connection. Other two risers are placed on smaller hot spots and have d1=

60 mm and h1= 250 mm, which do not have neck. This configuration shows

significant improvement in results over previous methods. See fig. 9.7.7 (page 41).

This is not good because of fillet and 4 no. of risers.

40



41


5. Fifth trial includes two no. of risers, both having d1= 130 mm, h1= 220 mm and have

neck connection with d2= 70 mm and h2= 30 mm (Refer fig. 9.5.3, page 31). The

risers are placed above two large hot spots. Fig. 9.7.8 (Page 42) shows that there is

better improvement in this method in terms of no. of risers and hot spot intensity.

6. Sixth trial is performed using two no. of risers, one having d1= 140 mm, h1= 230

mm, d2= 70 mm and h2= 20 mm which is placed on larger hole side. Other riser has

d1= 140 mm, h1= 230 mm, d2= 60 mm and h2= 20 mm which is placed on smaller

hole side. Fig. 9.7.9 (Page 42) shows that there is better improvement in this iteration

in terms of hot spot intensity.

7. Seventh iteration has two no. of risers, one having d1= 150 mm, h1= 230 mm, d2= 70

mm and h2= 20 mm which is placed on larger hole side. Other riser has d1= 150 mm,

h1= 230 mm, d2= 60 mm and h2= 20 mm which is placed on smaller hole side. Fig.

9.7.10 (Page 43) shows that there is large drop in hot spot intensity.

8. Eighth modification also has two no. of risers, one having d1= 160 mm, h1= 230

mm, d2= 70 mm and h2= 20 mm which is placed on larger hole side. Other riser has

d1= 160 mm, h1= 230 mm, d2= 60 mm and h2= 20 mm which is placed on smaller

hole side. Fig. 9.7.11 (Page 43) shows the result of simulation which is even better

than previous trial.

42



43



44

9. Ninth modification also has two no. of risers, one having d1= 175 mm, h1= 230 mm,

d2= 70 mm and h2= 20 mm which is placed on larger hole side. Other riser has d1=

175 mm, h1= 230 mm, d2= 60 mm and h2= 20 mm which is placed on smaller hole

side. Fig. 9.7.12 shows the result of simulation which is slightly better than previous

trial result.


10. Tenth trial has two no. of risers, one having d1= 200 mm, h1= 230 mm, d2= 70 mm

and h2= 20 mm which is placed on larger hole side. Other riser has d1= 200 mm, h1=

230 mm, d2= 60 mm and h2= 20 mm which is placed on smaller hole side. Fig. 9.7.13

(page 45) shows the result of simulation which almost nullifies effect of hot spot and

completely shifts the hot spots within risers.

For all these trials, excessive use of the foundry website named efoundry.iitb.ac.in ,

is made.

45


After carefully observing all these simulated results, one has to optimize between

level of defect allowed and casting yield.

It is clear that by adopting 9th

or 10th

iterations, chances of defect (particularly

shrinkage) reduce drastically with large reduction in casting yield.

If customer allows some percentage of shrinkage defects then accordingly specific

iteration is chosen for actual casting process.

If the customers provide excessive tight tolerances for defects then the overall cost of

production increases due to increased foundry efforts and large drop of casting yield

because of selecting either 9th

or 10th

proposed method.

In this way simulation provides powerful tool to method engineers to optimize the

gating and feeding system through virtual and less time taking simulation trials.

46

9.8 Comment on other frequently occurring defects:

Let’s again visit the temperature distribution of EP20 casting alone as shown in fig.

9.8.1.

Fig. 9.8.1 Simulation result of EP20

The solution for reducing or eliminating the HOT SPOTS i.e. WHITE LOCATIONS is

already obtained by optimizing the riser design and locations (Refer section 9.7).

The COLD SPOTS i.e. BLUE LOCATIONS indicates probable locations of occurring

the COLD SHUT. This is because; the blue regions are early freezing regions (fig. 9.7

and page 36). Due to large temperature gradients, chances of induced residual stresses

increase which may lead to cracking.

− The problem of COLD SPOT can be solved by performing very complex FLOW

SIMULATION process.

− Other way of reducing or eliminating these problems is to analyze the past records

to find out locations of these defects in previously cast EP20.

− After knowing these locations, appropriate amount of PADDING at appropriate

locations so as to minimize temperature difference.

− Padding may be BASE METAL type or FOREIGN MATERIAL type.

− This method is simply described as increasing the thickness of critical sections of

the casting.

Sometimes MISMATCH also occurs in the castings (Refer fig. 9.3 and page 26). This

cannot be eliminated by any simulation software. This is because of the nature of

defect i.e. only because of FOUNDRY PRACTICE. It has large dependence on

operator’s accuracy in clamping mold boxes and location accuracy of pattern plates

on molding machines.

47

CONCLUSION

EP 20 Casting produced by FINE CAST foundry fails to provide the soundness

frequently due to defects such as Shrinkage, Cold shut, Crack and Mismatch.

Out of these defects, Shrinkage, Cold shut and Crack can be reduced by optimizing the

design of Gating and Feeding systems. Mismatch is the defect occurring due to operator

error or pattern plate positioning error and cannot be reduced or eliminated with an aid of

simulation software.

Since manual iterations for optimizing the design require huge amount of time and

money, it is customary to use Casting Simulation Software for this purpose.

Simulation software gives the results for solidification simulation, flow simulation as

well as coupled simulation by providing required inputs.

Solidification simulation gives the locations of hot spots in the solidified casting and feed

paths thus helps in determining riser/feeder location and geometry.

We have performed solidification simulation trials result of whose can be visualized by

temperature distribution and probable locations of occurrence of shrinkage can be known

and the problem can be rectified using proper rectification.

Flow simulation gives ideas about mold filling by which solidification time and mold

filling time can be known. Also, flow related defects can be predicted and may be

prevented. Flow related defects are cold shut, cracking, etc.

In short, simulation technique aims at improving casting yield as well as reduces

rejections which ultimately lead to the higher profits.

48

REFERENCES

Research and Review Papers

1. K.D. Carlson, R.A. Hardin, Shouzhu Ou & C. Beckermann, “Development of new feeding

distance rules using casting simulation: Part 1. Methodology”, Metallurgical and

materials transactions B; vol 33 B, October 2002-731

2. K.D. Carlson, R.A. Hardin, Shouzhu Ou & C. Beckermann, “Development of new feeding

distance rules using casting simulation: Part 2. The new rules”, Metallurgical and

materials transactions B; vol 33 B, October 2002-741

3. B. Ravi, R.C. Creese & D. Ramesh, “Design for casting- A new paradigm for preventing

potential problems”, Transactions of the American Foundry Society, 107, 1999

4. K. Singh, P.K. Reddy, D. Joshi, K. Subburaj & B. Ravi, “3D junctions in castings:

Simulation based DFM Analysis and Guidelines”, INAE- ICAMT 2008, Feb. 6-8, 2008

5. B.G. Thomas, “Issues in thermal-mechanical modeling of casting processes”, Iron &

Steel inst. Of Japan International, Vol.35, No. 6, 1995,pp.737-743

6. Mark Jolly, “Casting Simulation: How well do reality and virtual casting match? State of

the art review”, Int. J. Cast Metals Res., 2002, 14, 303-313

7. Z. Guo, N. Saunders, A.P. Miodownik & J.-Ph. Schille’, “Modeling of materials

properties and behavior critical to casting simulation”, Materials science and

engineering A 413-414 (2005) 465-469

8. Dr. B. Ravi, “Casting Simulation and Optimization: Benefits, Bottlenecks, and best

Practices”, Tech. paper for Indian Foundry journal Jan. 2008 Special issue

9. Dr. B. Ravi, D. Joshi & K. Singh, “Part, Tooling and method optimization driven by

Castability analysis and cost model”, 68th

world foundry congress, Chennai, 7-10 feb.

2008

10. T.R. Vijayaram, S. Sulaiman, A.M.S. Hamouda & M.H.M. Ahmad, “Numerical

simulation of casting solidification in permanent metallic molds”, Journal of materials

processing technology 178 (2006) 29-33

11. Dr. B. Ravi, “Casting simulation- Best practices”, Trans. Of 58th

IFC, Ahmedabad

(2010)

12. B. Ravi & M.N. Srinivasan, “Feature recognition and analysis for molded components”

13. Dr. B. Ravi, “Computer aided casting method design, simulation and optimization”, Inst.

Of Indian Foundry men (Indore chapter), 13 march 2008

14. V.M. Gopinath, A. Venkatesan & A. Rajadurai, “Simulation of casting solidification and

its grain structure prediction using FEM”, Journal of materials processing technology

168 (2005) 10-15

15. B. Ravi & M.N. Srinivasan, “Casting solidification analysis by modulus vector method”,

Int. J. Cast metals Res. 1996, 9,1-7

16. K.S. Chan, K. Pericleous & M. Cross, “Numerical simulation of flows encountered

during mold filling”, Appl. Math. Modeling, 1991, vol. 15, nov./dec.

49

Reference Books & Other Resources

17. R.A. Flinn, “Fundamentals of Metal Casting”, Adison-Wesley Publishing Company Inc.

18. R.W. Heine, C.R. Loper & P.C. Rosenthal, “Principles of Metal Casting”, Tata McGraw

Hill Education Pvt. Ltd.

19. Peter Beeley, “Foundry Technology”, Butterworth Heinemann Pub.

20. B. Ravi, “Metal Casting- Computer aided Design & Analysis”, PHI Learning Pvt. Ltd.

21. P.N. Rao, “Manufacturing Technology- Foundry, Forming and Welding”, Tata Mcgraw

Hill Education Pvt. Ltd.

22. O.P. Khanna, “A Textbook of Foundry Technology”, Dhanpat Rai Publications Pvt. Ltd.

23. Web Resource: efoundry.iitb.ac.in

external final report (modified)

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