FOUNDRY TECHNOLOGY

MINI PROJECT

FINAL REPORT

The report submitted by,

A Mini Project Report on

FOUNDRY TECHNOLOGY

Submitted to the dept. Of Mechanical, PCET

In the Partial fulfilment of the academic requirements for the award

of

B.TECH (MECH) under JNTU

by

Mr.V.VENKATESH (08L71A0317)

Mr.M.RAKESH (08L71A0344)

Mr.B.CHAITANYA (08L71A0348)

Under the guidence of

Mr. RAMESH Mr.SURYANARAYANA

Asst.Proffesor HINDUJA FOUNDRIES

PCET External Guide

Internal Guide

Department of Mechanical Engineering

2011

ACKNOWLEDGEMENT

I wish to sincerely thank, Mr Suryanarayana, who was my mentor and guide during the course of this project. His valuable and timely inputs proved immensely useful to me and helped me in the successful completion of the project.

I also thank Hinduja Foundries for providing me with grate Opportunity such as this and believed that this training will go along in helping my future endeavours in this aspect of Mechanical Engineering .

I wish to sincerely thank, Mr.V.P.RAJU, Head of the Department, Mechanical engineering Department. Princeton college of engineering (pcet), as my internal guide gave his valuable inputs during the course and successful completion of the project work.

Finally my humble regards to all the people of Hinduja Foundries and PCET who have given me valuable suggestions during the course of the project were very much beneficial for me and helped me complete it successfully

V.VENKATESH

M.RAKESH

B.CHAITANYA

A brief introduction to Hinduja Foundries

Hinduja Foundries Limited is formely known as Ductron Castings Unit (DCU).DCU was founded and established by P.Ganapathi Sastri in the year 1972.Consequent to the establishment of DCU ,It has out grown into a well infrastucture unit for the development and manufacture of castings .DCU was well known in the automotive sector not only in and around Hyderabad but also all over the country as supplier of quality castings for their products .

In the course of time DCU was acquired by ASHOK LEYLAND, the Hinduja Group Company, well known in the country as the largest producers of trucks and other light commercial Vehicles (LCVs).

Later ASHOK LEYLAND DCU was transformed to Ennore Foundries and to the present recognition of Hinduja Foundries. Transformation process was only as a part of strategic management decisions from time to time.

Customers of Hinduja Foundries , to mention a few of them are Tata motors ,Mahindra & Mahindra tractors, John Deere, Hollansd tractors , Escorts Tractors (ETL), TAFE etc ,. Customer base will its own about the capabilities of the organisation.

For the last two successive years 2009-2010, 2010-2011 the turnover of the company was 100, 125 crores respectively.

CONTENT

1.Introduction

2.Process of casting

3.Pattern shop

4.core shop

5.Molding sand preparation

6.Molding shop

7.Molding area

8.Fettling shop(A)

9.Fettling shop(B)

10.Inspection and defects

INTRODUCTION:

FOUNDRY:

A foundry is a factory that produce metal casting. Metals are cast in to shapes by melting them into a liquid, pouring the metal in a mould, and removing the mould material or casting after the metal has solidified as it cools.

Doctron castings unit of Hinduja foundries manufactures automobile spare parts.hrer castings are made from Grey Iron and Spheroidal graphit(SG) Iron.the out put of this production facilitiey is up to 36000 tonnes per annum.

The process of production of castings as a whole includes the following improtant processes.

Design and development of patternCore makingMold preparation (molding)Melting and meltal pouring Shaking outShot blastingFettlingPaintingQuality assessment

PROCESS OF CASTING:

pattern

Core Boxes Moulds Molten Metal

cores

Closed Moulds

Pored Moulds

Rough Casting

Cleaned Casting

Finished Casting

Casting terms:

Moulding shop Melting shopPattern shop

Core shop Moulding-Closing Bay

Pouring Bay

Knockout Section

Shot Blasting Section

Fettling Shop

Shipping Yard

1.Flask: A metal or wood frame, without fixed top or bottom, in witch the mold is formed. Depending upon the position of the flask in the moulding structure, it is referred to by varies names such as drag-lower moulding flask, cope- upper moulding flask,cheek-intermediate mouklding flask used in three piece molding.

2.Pattern: It is the replica of the final object to be made. The mould cavity is made with the help of pattern.

3.Parting line: This is the dividing line between the two moulding flasks that makes up the mould.

4.Core: A separate part of the mold, made of sand and generally baked, which is used to creat openings and various shaped cavities in the castings.5.Pouring basin: A small funnel shaped cavity at the top of the mold into which the molten metal is poured.

6.Spure: The passage through which the molten metal,from the pouring basine,reaches the mold cavity.in many cases it controls the flow of metel in to the mold.

7.Runner: The channel through which the molten metal is carried from the sprue to the gate.

8.Gate: A channel through which the molten metal enters the mold cavity.

9.Chaplets:are used to support the cores inside the mold cavity to take care of its own weight and overcome the metallostatic forces.

10.Riser: A column of molten metal placed in the mold to feed the casting as it shrinks and solidifies. It is also termed as feed head.

11.Vent: Small opening in the mold to facilitate espace of air and gases.

Pattern Shop :

The process of production of castings begins here.

Pattren Making:

1. A pattern is a model or the replica of the object to be cast.2. Except for various allowances a pattern exactly resembles the

cast to be made.3. A pattern is required even if one object has to be cast.4. Materials used in pattern making are:-1. Cast iron2. Aluminum3. Araldite

Functions of patterns:

A pattern prepares a mold cavity for the purpose of making a casting.

A pattern may contain projections known as core prints if the casting requires a core and need to be made hallow.

Pattern properly made and having finished and smooth surfaces reduce casting defects.

Properly constructed patterns minimize overall cost of casting. Here in Hinduja Foundries, we use Split type Pattern.

Types Of Patterns:

1. Single piece pattern.

2. Split piece pattern.

3. Loose piece pattern.

4. Match plate pattern.

5. Sweep pattern.

6. Gated pattern.

7. Skeleton pattern.

8. Follow board pattern.

9. Cope and drag pattern.

Single piece(Solid)pattern: Made from one piece and does not contain loose pieces

or joints. Inexpensive. Used for large size simple castings. Pattern is accommodated either in cope or in drag.

Split piece pattern: Pattern of intricate shaped castings cannot be made in

one piece because of inherit difficulties associated with molding operation.

The upper and lower parts of the split pieces are accommodated in cope and drag portion of the molds respectively.

Parting line of pattern forms parting line of mold. Dowel pins are used for keeping the alignment between

two parts of pattern.

Typical Components Of A Two-Part Sand Casting Mold.

Pattern layout:

Get the working drawing of the part for which the pattern is to be made.

Make two views of the part drawing on a sheet using a “shrink rule”. A shrink rule is modified form of an ordinary scale which

has already taken care of shrinkage allowance for a particular metal to be cast.

Add machining allowances as per the requirements.

Depending up on the method of molding provides the draft allowance

Allowances:

Shrinkage or contraction allowance. Machining or finishing allowance. Distortion or cambered allowance. Shake or rapping allowance.

CORE SHOP

There are three methods of core making.1. Cold box process.2. Hot box process or Shell core process.

3. Co2 core making process.

Cold box core process :

In this process the binder is two component system:-

a) Polyol-phenolic formaldehyde resin b) Polyisocynate

This is mixed with silica sand ,and tri ethyl amine (TEA) is added

as a catalyst for the curing process .

The mixture of silioca sand the binders is placed in a reservoir and is shot below into the core box using shooter or sand magazine , which is the tool head that shoots into the box.

Tri –ethyl gas is passed into this box to be used as catalyst for curing . The time taken for each core depends on the required core dimension.

The core can be used within 1 weak of manufacture

Hot box core or shell core process : In this process silica sand mixed with with thermo plastic resin. The mixture is shot into the heated metal core , which is heated

up to 250 degrees centrigrade . Shell modes are made in halves which are then gloved and

clipped together. Core made by this process have excellent surface finish and

dimensional accuracy . This core can be used within 1 month of its manufacture.

CO2 core making process :

Ordinary sand is mixed with sodium silicate . Mixture is the rammed into the core box .It is manually

compacted and squeezed into the core box then core box is tapped and removed from the core box.

Core produced are painted with graphite or alcohol and pre-heated to obtain smooth finish.

This type of core is to be used within 24 hours.

Sand Mixer

Silica sand

Chemical binder

Core Machine

Gas CatalystFume Surbber

Core Box

Core Finishing

Core Racks

Core Setting

The above flow chart shows the core making procedure.

MOLDING SAND PREPARATION

Major parts of molding materials in sand castings are:

1. Silca sand (sio2).2. Binding material.3. Water.

Green sand preparation :

Sand used:Unit sandsystem.(All the properties are same at any location of the mold ).

These expandable mods are made of wet sands that are used to make the mold’s shapes. The name comes from the fact that wet sands are used in the molding process. Green sand is not green in color, but “green”in the sense that it is used in a wet state(akin to green wood). Unlike the name suggests, “Green sand” is not a type of sand on its own, but is rather a mixture of:

Silica sand (sio2), or chromite sand (fecr2o),or zircon sand (zrsio4),74 to 85%

Bentonite (clay),5 to 11% Water, 2 to 4% Anthracite (0 to 1%) Lustron for carbon 5%

]

Sand Mixer :

They are of two ie “ TM 240” and “TM 190”. TM 240 mixer consists of two impellers , one measuring

vessel and an arm whereas TM 190 consists of only one impeller , one measuring cylinder of the arm in the arm.

The numberds 240 and 190 in “ TM 240” and “TM 190”represents the length of the arm in the mixer.

The output capacity for “TM 240” mixer is 1.5 tonnes . The output capacity for “TM 190” mixer is 750 kgs. There are many recipes for the proportion of clay , but they

all strike different balances between mold ability , surface finish , and ability of the hot molten metal to degas .The coal typically reffered to in foundries as sea-coal, which is present of the molten metal leading to off gassing of organic vapors.

The above picture shows a continuous foundry sand mixer.

Molding Sand Properties :

Refractoriness :

It is the ability of the molding material to resist the temperature of the liquid metal to be poured so that it does not get fused with the metal . the rafractories of the silics sand is highest .

Permeability :

During pouring and subsequent solidification of a casting , a large amount of gases and steam is generated .These gases

are those that have been absorbed by the metal during melting ,air absorbed from the atmosphere and the steam

generated by the molding and core sand .If these gases are not allowed to escape from the mold , they would be entrapped inside the casting and cause casting defects .To overcome this problem the molding material must be porous.Proper venting of the mold also helps in escaping that are generated Iinside the mold cavity.

Green Strength :

The molding sand that contains moisture is termed as green sand particles must have the ability to cling to each other to impart sufficient strength to the mold . The green sand must have enough strength so that the constructed mold retains its shape.

Dry Strength :

When the molten metal is poured in the mold , the sand around the mold cavity is quickly converted into dry sand as the moisture in the sand evaporates due to the heat of the molten metal.At this stage the molding sand must posses the sufficient strength to retain the exact shape of the mold cavity and at the same time it must be able to withstand the metallostactic pressure of the liquid material.

Hot Strength :

As soon as the moisture is eliminated , the sand would reach at a high temperature when the metal in the mold is still in liquid state.The strength of the sand that is required to hold the shape of the cavity is called hot strength.

Collapsibility :

The molding sand should also have collapsibility so that during the contraction of the solidified casting it does not provide any resistance , which may result in cracks in the castings . Besides these specific properties the molding material should be cheap , reusable and should have good thermal conductivity .

Molding Shop :

A mold is a hollowed-out block that is filled with a liquid like plastic , glass , metal , or ceramic raw materials .The liquid hardens or sets inside the mold , adopting its shape .A mold is the opposite of a cast . The manufacture who makes the molds is called the mold maker . A release agent is typically used to make removal of the hardened/set substance from the mold easier.

In Hinduja Foundries LTD the mold is prepared using

“ High pressure molding machine”

High Pressure Molding Machine :

The dimension of molding sand box is 1150*750*350mm

Steps involved in making a casting:

MOLDING

BOX SEPARATION

BOX/PALLET CUTTING

TURN OVER

CORE PLACING

CLOSURE

POURING

COOLING

PUNCH OUT

It operates on the principle of shoot and squeeze . Shooting is the process where sand is shot from the

top. Ones the cope/drag goes inside, the cylinde4r lifts it

to the top and sand is shot inyo the mold box. This operation takes place on oneumatic pressure at

2 Bar. Sand is shot from the top with 2 bar pressure for the

uniform distribution. Squeezing is the process to squeeze the sand in the

mold box under high pressure to get the required density and hardness of the mold.

Process of Squeezing takes place with the help of hydraulic press at high pressure between 140 – 160Bar.

Here this machine has the capacity of making 60 molds per hour.

Levelling : This operation is done to level the sand after shooting and squeezing

Venting : It is done for the ferrostatic gases to escape.

Closing Devices: They are used to seal the cope and drag.

The picture shows shoot and squeeze operations.

Melting area

Melting and pouring:

Melting is performed in a furnace. Virgin material,external scrap,internal scrap,and alloying

elements are used to charge the furnace. The process include melting the charge, refining the melt,

adjusting the melt chemistry and tapping in to a transport vessel.

In a foundry, molten metal is poured into molds. Many modern foundries use robots or automatic pouring

machines for pouring molten metal Traditionally ,moulds were poured by hand using ladles. These ladles are moved with the help of Over Head

Cranes(E.O.T)

THE ABOVE IMAGE SHOWS A FOUNDRY MAN WORKING ON LIQUID METAL IN THE LADLE.

Cast iron and mild steel which is in the form of scrap is used for melting.

Gray Iron : 1400+or -5 degrees pouring temperature . SG : 1480 to 1500 degrees centigrade pouring temperature.

100% pouring metal =60% MS scrap+40% foundry returns.

Fettling (A) SHOP

The castings here are not of the required shape.The risers and the gating system used for pouring metal into the mold are still attached to the casting.

The risers and the gating system are removed first from the casting manually using hammers and small leftovers projection or those which cannot be removed using machine cutters .

Fettling :

The removal of feeders and excess material from a casting – is the first stage of finishing a casting. The metal removal is often achieved using manual cutting or grinding . However, more emphasis is being placed on automatic fettling , where by casting is placed in a machine programmed to remove materials from specific areas. The method of fettling must be taken into account at the initial casting design stage , so that the process is fast and efficient.

Shot Blasting :

Abrasive particles, such as sand , grit or steel shot (3mm diameter), are propelled at high velocity to impact the casting surface to remove surface contaminents. In general shot blasting concentrates abrasive particles at high speed (65-110 m/s) in a controlled manner at the material thereby removing surface contaminates due to the abrasive impact. Propulsion of the abrasive particles is usually achieved using a centrifuge or compressed air nozzles.

Shot Blasting is commonly used for :

The cleaning of iron , stell ,non –cast parts , forgings ,etc. Mechanical cleaning of sheets ,rods ,coils ,wires,etc. Shot peening to alter mechanical properties (increasing

resistance to fatigue for springs , gears , etc.) Preparind surfaces to be painted, coated, etc.

Fettling (B) shop (finishing)

The castings after shot blasting are transported here.Here grinding of the casting surface is done .This is done to remove small projections left over after removal of riseers and gating system

Grinding :

It is done by grinder made up of an abrasive substance like silicon carbide which removes the projections on the casting surface by abrasion.

It is done by hand held grinding machines and a large grinding machine.

Heat Treatment :

The application of heat to a casting to alter the material properties making them suitable for the finished product or for subsequent processing.Heat treatments can be achieved in a number of ways ,

Inncluding induction heating ,furnace heating and localiized flame heating , amongest others.

Cleaning :

It is Non-mechanical removal of surface contaminents .Parts are submerged in different solutions , depending on the requirements of the cleaning process and any subsequent operations .Typical

treatments are : molten salt baths used for electrolytic cleaning , acid baths for pickling, chemical cleaning and organic solvent cleaning.

Coating :

Purpose of surface coating is to impart resistance to corrosion , wear and erosion. coating tecniques include electroplating, hot dip coatings ,hard facing ,thermal spraying and painting.

Painting :

Painting is either done by dipping the casting in paint basin of required colour or by spraying uniformly, which is spray painting.

At DCU only painting is done ,by dipping the casting in paint basin.The painting is done only for rust : the single coat of primer is applied over the surface of casting.

Inspection And Defects

Inspection Methods :

1. Process inspection

2. Visual inspection

3. Pressure testing

4.Radio graphy

5.Magnectic practice testing

6.Penetrate testing methods

7.Ultrasonic testing methods

Casting Defects :

A casting defect is an irregularity ion the metal casting process that is undesired.Some defects can be tolerated while others can be repaired otherswise they must be eliminated .They are broken down into five main categories : gas porosity, shrinkage defects ,mold material defects ,pouring metal defects , and metallurgical defects.

Gas Porosity :

Blow holes and open blows –Blows : They are caused if venting is not done properly.

Air inclusion Pin holes :There are three reasons for the formation of pin

holes .1) If paint thickness is excess2) Hydrogen bubbles in the molten metal during poourning .3) Sand accumulation in gates.

Shrinkage Cavities :

Shrinkage defects occur when feed metal is not available comensate for shrinkage as the metal solidifies.

Shrinkage has two reasons because of high temperatures and sudden cooling or metal not sufficient.

Molding Metal Defects :

Cuts and washes Metal penetration Fusion Run out Swell Sand Drop: it is due to the sharp corners of the

sand mold.If core is not placed properly sand and

mold crush takes place.

Pouring Metal Defects :

Miss match : It is a defect which is observed to the naked eye.It is basically the uneven dimensions on

the final product. Slag: Slag is appeared on the final product through

thick holes , when slag is not properly removed during the pouring process from the ladle.

Gas Porosity :

Shrinkage cavities

Metallurgical defects

Hot tears Hot spots

If a casting goes through all the quality checks without showing any defects it is then said to have all the quality standards and is shipped to clients.

CONCLUSION To prepare a metal/alloy component parts of desired shapes, we have to follow these processes pouring the molten metal/alloy in to a prepared mold(of that shape) and then

allowing the metal/alloy to cool and solidify. This will make our required casting.