Foundry Edited

8/3/2019 Foundry Edited

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FOUNDRY SHOP

INTRODUCTION:

BCL, Angus works, Bhadreswar manufactures steel castings of different categories for

the customer to the level of customer satisfaction and reliability following the satisfactory

and regulatory regulations. Its commitment towards customer is obtained by:

1. Involvement of people in its organisation through training and education

2. Creating a strong customer focus.

3. Ensuring continual improvement.

4. Following the quality system under the framework of ISO 9001-2000.

The total foundry shop can be subdivided into the following steps of process flow:

Pattern making. Moulding. Core making. Steel melting. Fettling & Heat treatment. Laboratory & Testing lab.


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PATTERN MAKING :

INTRODUCTION:

In this shop different replicas made of wood are prepared as different sections of the

whole casting. The part replica of original casting is made as per the drawing and layout.

After the process discussed below is followed, the parts are sent to the mould making shop

for sand mould preparation.

PROCESS:

After studying the drawings carefully the layout is made into 1:1 scale consideringthe entire pattern, making allowances on the pattern making board.

Then choosing of the pattern line is done and core prints are provided if necessary. The material is selected i.e., wood, plastic or metal. If the pattern material is wood, it is made plane by planning m/c to get the required

thickness.

Sawing and chiselling operation is done to produce the pattern according to thelayout.

If the pattern material is either plastic or metal, a master pattern is made fromwood.

If the material is thermocol, sawing and cutting according to the layout is done.


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MOUNTING:

For m/c moulding the patterns are mounted on different sized plates at the different

moulding sections. The patterns are mounted in MS plate at the different moulding sections

either by screws or nut bolts. Gating risering systems are provided in the plates as per the

approved methods sheet.

The pattern and core boxes are thoroughly checked and inspected before sending tomoulding and core shop for sample casting.

Sample casting is marked for dimensional check-up and if found defective, thepattern and core boxes are rectified till it is ok.

If the pattern and core boxes are found acceptable they are released for regularproduction.

MOULDING:

INTRODUCTION:

In the moulding shop the mould is made part by part of the whole casting and fitted in

the copes &drags by the prepared sand i.e. facing and backing sand in the jolting m/c of

capacity 10000 Ibs. The prepared mould is send to the zone where the melted steel is

poured into it.

SAND PREPARATION:

One of the important requirements for the preparation of sand is a thorough mixing of

its various ingredients. This is essential to ensure uniform distribution of the various

components in the entire bulk of the sand. During the mixing process, any lump present in

sand is broken up and clay is uniformly enveloped around the sand grains and moisture is

uniformly distributed.

The properties that the moulding sand should generally possess are:

PARAMETERS FACING SAND BACKING SAND

Moisture 3.5 - 4.5% 3.5 - 5%

Green Compression Strength 8 - 10 psi 7 - 10 psiPermeability 150 - 250 150 - 250

Green Shear Strength 3 - 4 3 - 4

Shattering Index 80 - 85% 80 - 85%

Compactibility 50 - 60 50 - 60

Flowability 75 - 80 -

Mould Hardness 80 - 90 70 -90

Scratch Hardness 65 - 75 65 - 75


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SAND PLANT SHOP:

Sand is mixed with proper additives and other auxiliary material like Bentonite, Dextrine,

Iron oxide, Saw dust, Starch and proper amount of moisture through the sand mixture. Two

types of sand are produced -:

I. Green sand.II. Backing sand.

After the sand is mixed and is prepared to make the mould, then the prepared sand is

send for mould making through conveyer belt and pipes.

PROCESS:

1. SILICA GREEN SAND MIX(GENERAL PURPOSE) :Batch capacity 300 kg

Sand mix 30% Dry 90kg

70% Dry 270kg

INGREDIENTS WEIGHT PERCENTAGE OF

SAND

TOTAL WEIGHT

Bentonite 6 to 8% 18/24kg

Dextrine 1 to 1.5% 3/4.5kg

Iron oxide 0.5 to 1% 1.5/3kg

Saw dust 0.5 to 1% 1.5/3kg

Starch 0.5 to 1% 1.5/3kgMoisture 4 to 4.5% 12/13.5kg

MULLING:

I. 2 min Dry.II. 3 min Wet.

III. 90 sec at faster rate.2. DRY SAND(OLD) FOR CORE SILICA SAND :

Batch capacity 300kg.

INGREDIENTS WEIGHT PERCENTAGE

OF SAND

TOTAL WEIGHT

Oil 1.5 to 2% 4.5/6kg

Dextrine 2.5 to 4% 7/12kg

Bentonite 1 to 1.5% 3/4.5kg

Saw dust 0.5% 1.5kg


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The moisture and other ingredients may vary depending on the sand condition

regarding grain size and clay content.

MULLING:

I. 2 min Dry.II. 3 min Wet.3. SODIUM SILICATE SAND(GENERAL PURPOSE)- FOR MOULDING AND CORE

MAKING:

Batch capacity 300kg


SAND

TOTAL WEIGHT

Sodium silicate

a)For core

5 to 5.5% 15 kg

4.5 to 5%

Dextrine 0.5 to 1% 1.5/3kg

Bentonite

a)For core

2 to 3.5% 6/10.5kg

2 to 3% 6/9kg


Moisture 3.5% 10.5kg

MULLING:

I. Sand and sodium silicate are moulded thoroughly.II. Ingredients added and moulded for 3 to 4 min.

III. Protection from air.

4. RESIN BONDED SAND FOR CORE SAND (GENERAL PURPOSE) SILICA SAND:

Batch capacity 300kg

100% Dry sand temperature 25.3C


SAND

TOTAL WEIGHT

Resin 1.5 to 2% 2.25/3kg

Catalyst 35 to 40% of Resin 0.8/1.35kg

Saw dust(when required) Upto 2% 3kg


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MULLING:

I. Sand and Catalyst 1 min.II. 1/1.5 min after adding Binder.

5. RESIN BONDED SAND FOR CORE MAKING OF CMS CROSSING:

Sand chromate 300kg


SAND

TOTAL WEIGHT

Alkyd Resin 2 to 2.5% 4/5kg

Linking binder of Alkyd

Resin

18 to 22% 0.72/1.11kg

Accelerator of Alkyd Resin 5 to 10% 0.2/0.5kg

MULLING:

I. Sand and Resin 2 min.II. Add binder and continue for 3/4th min.

III. Rapid use of Accelerator.

6. GREEN SAND MIX FOR CAST MANGANESE STEEL CROSSING:

Sand chromate 300kg (100% Dry)


SAND

TOTAL WEIGHT

Bentonite 3 to 4% 12/15kg

Dextrine 1 to 1.5% 3/4.5kg


Moisture 2.5 to 3% 7.5/9kg

MULLING:

I. 2 min Dry.II. 5-6 min Wet.

III. 90 sec at faster rate.


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CORE SAND PREPARATION:

Cores are the materials used for making

cavities and hollow projections, which

cannot be normally produced by the

pattern alone. Any complicated contour orcavity can be made by means of cores so

that really intricate shapes can be easily

obtained. These are generally made of

sand.

The first condition in making a core is to

mix and prepare the sand properly. The sand used for making cores is called core sand. The

core sands are mixed in core muller. Sand (coming from sand drier) is mixed with resin (2%)

and catalyst (2% phosphoric acid). Furan process is followed in core sand preparation.

After the preparation of core sand is over,

the cores are prepared in the core boxes made

of wood or metal. The various steps in core

making are ramming of core sand in the box,

venting, reinforcing, removing of core from

box, baking, pasting, sizing etc. This work of

producing cores can either be done by hand or

by some machines designed for this purpose.

The normal characteristics desired of the core

sand are the following:-

Scratch hardness. Refractoriness. Permeability. Collapsibility. Friability. Smoothness. Low gas emission.

MOULDING PROCESS:

1. Checking of moulding m/c is done before starting operation.2. Pneumatic pressure is maintained at 6kg per sq.cm.3. Checking of pattern pin and core boxes, loose pieces, stock of sands (both facing and

backing) etc. are done.

4. Mould boxes, gaggers, stiffeners etc. are checked.


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5. Checking of chaplets, chills, nails are also done.6. Checking of mould hardness which must be (75-85) psi.7. Drying of sprue sleeve and runner cup is to be checked.8. Checking of mould and core washes and their proper drying.9. Checking of core positioning in the core print positioning of chaplets, chills, and nails.10.Checking of closing of mould assembly (copes and drags).11.Checking of proper pouring of liquid metal inside the mould cavity.12.Knock-out the poured mould after minimum of 12 hrs.13.Used sand is reclaimed to sand plant.

MELTING SHOP:

INTRODUCTION:

In this shop the steel is melted in the furnace. In Braithwaite foundry, two types of

furnaces are there -:

i. Electric Arc furnace.ii. Induction furnace.

Due to some disadvantages the Induction furnace is obsolete in this foundry, so Electric arc

furnace is used here for melting steel. The melted steel is carried to the moulding zone

where cope and drag assembly is kept through discharge wagon and steel holding pot and

poured into the mould through runner.

ELECTRIC ARC FURNACE:

For heavy steel castings, the furnace with electric arc is used because of the large heat

required for melting. The electric arc furnace consists of a refractory lined vessel which is

water-cooled and covered with refractory roof through which three graphite electrodes

enter the furnace. The electrodes are made of 99% pure graphite. The wall of the furnace is

lined with magnesite bricks and its roof is lined with alumina bricks. The furnace is primarily

divided into three sections:

y Shell consists of the sidewalls and the lower steel bowl.y Hearth consists of the refractory lines and the lower bowl.y Roof.This furnace draws an electric arc that rapidly heats and melts the charge material. Heat

is directly transferred to the charge metal from the electrode arc. The furnace has a tilting

mechanism allowing it to be tilted forward for metal tapping or backward for deslagging.

Once the melt is ready to pour, the electrodes are raised through the roof and the furnace is


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tilted to pour the molten

metal into a ladle. For

avoiding damage due to

high melting temperature,

water-cooling arrangement

has been kept.

The electric arc furnace

used in BCL foundry has a

capacity of 5 tonnes. It is a

model-8 arc furnace and has

a power rating of 2.5 MVA.

LADLE:

The molten metal from the furnace is tapped into a bucket-shaped container called ladle

after its preheating and then poured into the moulds. Depending on the amount of metal

to be handled, there are different sizes of

ladles ranging between 50kg to 30 tonnes.

In BCL foundry, bottom-pour ladles of 5

and 2.5 tonnes are used. This type of ladle

has an opening at the bottom from where

the molten metal is poured and it can

effectively separate the slag from the

metal. Here, a stopper rod is used which is

suspended inside the ladle. The stopper

rod is pulled up from its position, thus

allowing the molten metal to flow from the

ladle. The head of the stopper rod is made

of 99.9% pure graphite.

The lining of the ladle is made of

refractory fire clay bricks. The ladle is preheated to a temperature about 700-750C as to

avoid shock and damage during the tapping of the excessive hot molten metal from the

furnace.

TAPPING:

It is the operation of flowing of the hot molten metal from the furnace into the ladle.

When the melting temperature of 1620C is reached, the electrodes are raised through the


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roof of the furnace and as

a result the arc is cut-off.

The furnace is then tilted

at a certain angle and from

this moment the tapping

of the molten metal startsuntil it fills the ladle.

POURING:

It is the operation of

flowing of the hot molten

metal from the ladle into

the mould cavity. The

molten metal is not directly poured into the mould cavity as it may cause erosion of the

mould. The molten metal is first

poured into a pouring basin from

which it moves smoothly into the

sprue. From the sprue, the metal

is brought into the parting plane

where it enters the runners and

gates to ultimately reach the

mould cavity. The pouring

temperature is less than thetapping temperature due to heat

radiation. The bottom-pour ladle

is brought above the pouring

basin and then the molten metal

is poured by pulling the stopper

rod up from its position.

STEP BY STEP OPERATIONS:

1. Making the charge so that the initial C% is at least 0.4% above the specification.2. Putting of 100kg limestone and 50kg iron oxide at the bottom of the furnace.3. Melting down the charge completely.4. Sending the sample to spectrograph for checking of C, P, Mn, Si, & S% in the bath.5. Free boiling is done for at least 30 mins.6. Checking of C and P levels.


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7. If C and P levels are below the specification then slag off completely. Blocking thebath by adding Fe, Mn and Fe-Si.

8. Rabbling the bath and sending of sample for chemical analysis.9. Reducing the bath completely to reduce the S level below specification.10.Adjustment of the chemical composition by adding ferrous alloy.11.Checking of the final temperature before tapping.12.Adding 1kg Al per tonne for final di-oxidation.13.Ladle is preheated before the molten metal tapping.14.Molten metal is tapped into the ladle.15.The molten metal is poured into the moulds.

HEAT TREATMENT & FETTLING :

INTRODUCTION:

In this process the cast product is heat treated for removing plastic deformation and

other irregularities. The fettling or finishing of products are obtained by removing the extra

cast metal as scrap remover and also gas cutting is done to remove thick metals.

PROCESS:

1. GAS CUTTING:I. Casting received from foundry must be cleaned at riser and ingate area.

II. Decored castings are shot blasted before gas cutting operation of ingates andpads which should be properly performed. Any fins or extra metal areasshould also be removed to get proper casting size after gas cutting.

III. Good castings are sent for heat treatment and the rejected castings along withrunner and riser are sent to scrap yard and melting area.

If special alloy grade casting is to be gas cut, it is to be heat treated before gas

cutting operation.

2. HEAT TREATMENT:The body and the break work pores should be cleaned properly. The banner

and stock of oil should be checked before starting the heat treatment operation.

3. LOADING:The loading of heavy integrated castings are to be stacked properly so that

the flue gases can pass properly around each section of the casting. Small castings

may be dumped.


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HEAT TREATMENT CYCLE FOR DIFFERENT OIL FIRED BOGIE TYPE

ANNEALING:

FURNACE PROCESS TIME30 tonnes Heating at 900C 6-8 hrs

Soaking at 900C 3-4 hrs

Air cooling

4 tonnes Heating at 900C 4-5 hrs


Air cooling

6 tonnes Heating at 900C 4-5 hrs


Air cooling

QUENCHING CYCLE:

Heating up to 800-900C for 4 to 5 hrs. Soaking at 880-900C for 3 to 4 hrs. Quenching in oil/water.

TEMPERING OPERATION FOR THE ENTIRE FURNACE:

Raising to 600C 3 hrs. Soaking to 600C 2 hrs. Air cooling.

10T WESMAN FURNACE (CYCLE FOR Mn CROSSING):

Raising to 650-700C at the rate of 50-75C per hour and soaking for 2 hrs. Raising to 1050-1100C at the rate of 50-75C per hour. Soaking at 1050-1100C for 3 hrs. Quenching in agitated water within 50 secs.

SHOT BLASTING OF CASTINGS:

All castings are shot blasted properly so that reasonably cleaned surface is maintained

before the start of fettling operation. If salvaging is required, the shot must be gauged and

then salvaged with graded electrode for different classes of steel. Preheating and post

heating are required in some high alloy and carbon steel castings.


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FETTLING:

Chiseling and grinding must be done properly so that the original casting surface is not

damaged and also to prevent changes in the dimensions.

FINAL INSPECTION:

Castings are finally inspected by the Inspection & Quality Control department. Good

castings are despatched to different sections. Rejected castings are either salvaged or finally

rejected and sent to scrap yard.

FOUNDRY PRODUCTS:

CASTING NAME CASTING WEIGHT LIQUID METAL

REQUIREMENT

Bolster 565 kg 700 kg

Side Frame 430 kg 600 kg

Side Bearer 7 kg 10 kg

Backstop 25 kg 35 kg

Striker 76 kg 100 kg

Centre Pivot Top

(conventional)

54 kg 75 kg

Centre Pivot Bottom(conventional)

61 kg 85 kg

Centre Pivot Top (modified) 86 kg 106 kg

Centre Pivot Bottom

(modified)

62 kg 85 kg

Coupler Body 172 kg 240 kg

Yoke 100 kg 140 kg

Knuckle 35 kg 45 kg

Lock 7 kg 10 kg

Yoke Pin Support 30 kg 45 kg

Minor Follower 28 kg 40 kg

Draft Gear Housing 61 kg 100 kg

Date post:	06-Apr-2018
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