foundry & forging ppt

FOUNDRY AND FORGING LABORATORY

Subject Code : 10MEL38A / 48 IA Marks : 25

Hours/Week : 03 Exam Hours : 03

Total Hours : 48 Exam Marks : 50

PART – A

Testing of Moulding sand and Core sand

Preparation of sand specimens and conduction of the following tests:

Compression, Shear and Tensile tests on Universal Sand Testing Machine

Permeability test

Core hardness & Mould hardness tests

Sieve Analysis to find Grain Fineness number of Base Sand

Clay content determination in Base Sand

PART – B

2. Foundry Practice

Use of foundry tools and other equipments.

Preparation of moulds using two moulding boxes using patterns or without patterns. (Split pattern, Match plate pattern and Core boxes).

Preparation of one casting (Aluminum or cast iron-Demonstration only)

PART – C

Forging Operations

Calculation of length of the raw material required to do the model

Preparing minimum three forged models involving upsetting, drawing and bending operations

Out of these three models, at least one model is to be prepared by using Power Hammer.

Scheme of Examination

One question is to be set from Part-A : 10 marks

One question is to be set from either Part-B or Part-C : 30 marks

Calculation part in case of forging is made compulsory

Calculation + Forging = 05 +25 = 30 Marks(Forging) Model

Viva-Voce : 10 marks.

Total : 50 Marks

Foundry PracticeFoundry Practice

General Foundry Safety

Before using any equipment or materials, proper knowledge of its usage is required.

PPE protects you from the foundry environment. Wear leather shoes, gloves, and safety glasses with a side shield.

A hat with a brim protects you from spatters.

Use hearing protection in the noisy environment.

When directly working with molten metals, heat, and flame sources, add a hard hat, apron, jacket or cape, leggings, and spats made of leather, aluminized glass fabrics, synthetic fabrics or treated wool.

Foundry furnaces, crucibles, and metals are at such high temperatures, remain cautious while you work.

Do not work with equipment or processes that are unfamiliar to you.

Be conscious of where your hands are when working with conveyors and automated machinery.


Pour and melt in areas that have a nonflammable surface such as metal or sand.

Molten metal that is spilled can travel a great distance, so keep the work area clear.

Have a Class D fire extinguisher handy along with a shovel and clean, dry sand for extinguishing fires.

Melting metals create fumes that can be hazardous to breathe.

Melting scrap metals can create fumes from old paints, lubricants, and coatings and lead, nickel, or chromium additives that are hazardous to breathe.

Use good ventilation through exhaust hoods and wear a respirator that are medically approved, fit-tested, and trained to wear.

Molding sand often contains silica. Silica dust exposure can lead to silicosis, a lung disease, or lung cancer.

Use good ventilation with dust control measures such as non-toxic binding materials to control silica dust.

All equipment you use should operate properly.

Dehydration, heat cramps, heat exhaustion and heat stroke are some of the health effects foundry workers can experience from exposure to excessive heat.

Packing the molds, shaking them out, and cleaning the castings can also be a source of silica dust, so wear a respirator and work in a well-ventilated area.

Inspect foundry equipment on a frequent basis for cracks and signs of wear.

Never introduce water to the furnace or crucible. A trace amount of water can cause a large explosion.

Workers may also develop eye cataracts from infrared and ultraviolet radiation which can be emitted when pouring white hot metal.


The Process of Converting Raw Materials Into Products

Manufacturing ?

It includes

Design of the product

Selection of raw materials and

The sequence of processes through which the product will be manufactured

Introduction

Manufacturing Processes

Casting Machining Forming Joining

(Net shape primary process)

( Subtractive secondary process)(Net shape secondary process)

( Additive secondary process)

Introduction

Foundry: A foundry is a factory that produces metal castings.

Metals are cast into shapes by melting them into a liquid, Pouring the metal in a mold

Removing the mold material or casting after the metal has solidified as it cools.

The most common metals processed are Aluminium and cast iron.

Other metals, such as bronze, steel, magnesium, copper, tin, and zinc, are also used to produce castings.

Introduction

Casting: one of oldest and one of the most popular processes of converting materials into final useful shapes.

It involves a series of operations

Pattern making

Core making

Mould making

Melting

Pouring

Cleaning

Casting is the process of pouring molten metal in to a mould cavity of required shape & size and allowing for cooling

Introduction

Casting

Conventional Methods Unconventional Methods Green sand mould

Dry sand mouldCO2 Moulding (Strong mould)

Permanent (Metal mould)

Shell Moulding (Thin mould)

Investment casting (Precision)

Centrifugal ( without core)

Continuous Casting (Open)

Introduction

Introduction

Casting Terms

Pattern- replica of the part to be cast

Molding material- material that is packed around the pattern to provide the mold cavity

Core- sand or metal shape that is inserted into the mold to create internal features

Flask- rigid frame that holds the molding aggregate

Cope- top half of the pattern

Drag- bottom half of the pattern

Mold cavity - combination of the mold material and cores

Riser - additional void in the mold that provides additional metal to compensate for shrinkage

Gating system - network of channels that delivers the molten metal to the mold

Pouring cup - portion of the gating system that controls the delivery of the metal

Sprue - vertical portion of the gating system

Runners - horizontal portion of the gating system

Parting line - separates the cope and drag

Six Basic Steps of Casting

Pattern making

Core making

Moulding

Melting

Pouring

Cleaning & inspection

Introduction

The Pattern

replica of the part to be cast

Pattern materials:Wood - common material because it is easy to work, but it warps

Metal - more expensive to make, but lasts much longer

Plastic - compromise between wood and metal

Plaster of Paris

Wax –precision casting

Introduction

Types of Patterns(a) solid pattern ( single piece)

(b) split pattern ( Two piece)

(c) match‑plate pattern

(d) cope and drag pattern (e) Sweep pattern

(f) Skeleton pattern

Introduction

Core in Mold

A core consists of two portions: the body of the core and one or more extensions (called prints) Cores are used to create internal cavities. Core is a separate entity placed in a mould to produce a corresponding cavity – hole or undercut – in the casting Cores for sand casting are manufactured by packing specially prepared sand in core boxes Chaplets

Moulding

The cavity in the sand mold is formed by packing sand around a pattern, then separating the mold into two halves and removing the pattern

Major part of Moulding material in sand casting are

1. 85-90% silica sand (SiO2)

2. 3-7% bonding material e.g., clay cereal etc.

3. 3-6% water

Requirements of molding sand are:

(a) Refractoriness

(b) Cohesiveness

(c) Permeability

(d) Collapsibility

Introduction

Moulding sand properties

Porosity or Permeability

It is the property of sand which permits the steam and other gases to pass through the sand mould.

The porosity of sand depends upon its grain size, grain shape, moisture and clay components are the moulding sand. If the sand is too fine, the porosity will be low.

Plasticity

It is that property of sand due to which it flows to all portions of the moulding box or flask.

The sand must have sufficient plasticity to produce a good mould

Adhesiveness

It is that properties of sand due to it adheres or cling to the sides of the moulding box.

Cohesiveness

It is the property of sand due to which the sand grains stick together during ramming. It is defined as the strength of the moulding sand.

Refractoriness

The property which enables it to resist high temperature of the molten metal without breaking down o r fusing.

Classification of Moulding Sand According to their Use

Green sandThe sand in its natural or moist state is called green sand. It is also called tempered sand. It is a mixture of sand with 20 to 30 percent clay, having total amount of water from 6 to 10 percent. The mould prepared with this sand is called green sand mould, which is used for small size casting of ferrous and non-ferrous metals.

Dry SandThe green sand moulds when baked or dried before pouring the molten metal are called dry sand moulds. The sand of this condition is called dry sand. The dry sand moulds have greater strength, rigidity and thermal stability. These moulds used for large and heavy casting.

Loam SandA mixture of 50 percent sand grains and 50 percent clay is called loam sand. It is used for loam moulds of large grey iron casting.

Facing SandA sand which is used before pouring the molten metal, on the surface is called facing sand. It is specially prepared sand from silica sand and clay.

Backing or Floor Sand

A sand used to back up the facing sand and not used next to the pattern is called backing sand. The sand which have been repeatedly used may be employed for this purpose. It is also known as black sand due to its colour.

System Sand

A sand employed in mechanical sand preparation and handling system is called system sand. This sand has high strength, permeability and refractoriness.

Parting Sand

A sand employed on the faces of the pattern before the moulding is called parting sand. The parting sand consists of dried silica sand, sea sand or burnt sand.

Core Sand

The cores are defined as sand bodies used to form the hollow portions or cavities of desired shape and size in the casting. Thus the sand used for making these cores is called core sand. It is sometimes called oil sand. It is the silica sand mixed with linseed oil or any other oil as binder.

Hand tools used in moulding

In hand moulding processes, all the moulding operations, such as ramming the sand, placing and drawing the pattern,

turning over the moulding boxes, etc., are performed by hand

A number of hand tools which are used by the molder to perform above mentioned operations are shown below

Bellow : A bellow is used to blow loose sand particles from the pattern and the mold cavity

Lifter: It lifts dirt or loose sand from the mold. It is used for repairing and finishing the sand mold cavity

Heart & square: It is employed for finishing the mould cavity

Hand rammer: It is used for ramming the sand in molds

Sprue pin: It is tapered wooden rod which is placed in the cope to make Sprue cavity

Hand Riddle: It consists of wire mesh fitted into a circular wooden frame. It is used for cleaning, removing foreign matter from sand.

Trowels: used to finish flat surfaces of the mould, cut in gates, make joints or repair moulds.

Smoothers and corner slics: They are employed to repair and finish corners, edges, round and flat surfaces

Gate cutter: it is a shaped piece of sheet metal . It is used to cut the gate

Shovel : used to transfer moulding sand from store to place of use. Also used to mix and temper the moulding sand

Preparation of Sand MouldPreparation of Sand Mould

Preparation of sand mould

SAND CASTING

Before any casting can take place a wooden pattern is made precisely.

This is called pattern making and in industry this is a very skilful job.

Any inaccuracy at this stage will result in the final cast being wrong or even failing.

Drag is placed inverted on the mould floor and pattern is placed at the center of the box


Special casting sand will soon be packed around the pattern for easy removal of pattern from parting powder is sprinkled over and around it.

It stops the casting sand sticking to the pattern and pulling away with it when the pattern is finally removed from the sand.

Casting sand is then shaken through a sieve (called riddled sand) so that only fine particles fall around the pattern.

This is called facing sand and it must be fine so that detail on the pattern shows up on the final casting.


The drag is then packed with more casting sand and then ram it down firmly using a ramming tool.

The tool has two ends, one is cylindrical and is used for general packing down of the sand.

The other end is quite pointed and this can be used for packing sand close up to the pattern.

When the drag is packed fully it is levelled off (called ‘strickled off’) using a straight steel bar.


The entire drag and its contents are then turned over so that the base of the pattern can be seen


A top box called a ‘cope’ is then placed on top of the drag and locating pins are put in position so that the casting boxes cannot move sideways


Sprue pins are positioned.

One usually on the back of the pattern and the other to the side.

These will eventually provide an entrance and exit for the molten aluminium when it

is poured into the sand.

The sand is packed/rammed into the cope in the same way as the drag


The top box (the cope) is then removed and if all is well the cope with the sand inside should lift off the drag

(bottom box) without the sand falling out.

A small ‘gate’ is cut below the position of one of the Sprue pins.

This will help the molten metal to flow into the cavity left by the mould.

Small tools are available or can easily be made to dig a variety of shapes in the casting sand.

They are similar to small trowels

The pattern is removed using a ‘spike’.

Before removing the pattern it is a good idea to gently tap the spike so that it loosens the pattern from the sand.

It can then be lifted away from the casting box (drag).


The cope (top casting box) is placed back on top of the drag and the locating pins put in position.


Vents can be created using a thin piece of welding rod, pushing it through the sand

This allows gases to escape once the molten metal is poured.


The molten metal is poured with great care.

The molten metal is poured down the hole left by the first Sprue pin (now called the ‘runner’).

As it runs down the runner it flows through the ‘gate’ cut by the trowel, into the cavity left by the pattern and up the riser (the hole left by the second Sprue pin).

The casting should be left for at least an hour before removal from the sand

When removed from the sand, the runner and riser are cut away and the casting is ready for machining

Sand TestingSand Testing

Sand Testing

Each foundry should draw out a minimum test programme which should be strictly followed for

control of the sand system

Controlling quality of sand in a foundry is very important as the quality of the casting depends on the

quality of the mould sand

The quality of the mould and core depends on the sand, binder, additives used & also on the

percentage of each of the constituents

Sand testing provides clues for improving casting quality

Since molding sands and core sands are important in foundry operations, their control and testing is

essential

Sand control tests are performed on the sand which has been prepared and is ready to be transferred

to the moulding section

Why Sand testing?

Testing of mould & core sand

Sand Testing

Preparation of standard test specimen

Mould hardness test

Core hardness test

Moisture content test on foundry sand

Sieve analysis

Clay content test

Permeability test

Compression, shear & Tensile test

Preparation of standard test specimen

Sand Testing

The standard specimen is prepared using a standard sand rammer and specimen tube accessories.

The specimen is rammed with three blows.

This is the standard procedure.

This operation that is ramming sand three times compacts the sand to a standard hardness

The weight of the ram may be 63-72 N by weight

The ram is dropped from a height of 50mm

Sand Rammer

Sand Rammer

Sand Testing

Mould Hardness Test

Mold surface hardness is the resistance offered by the surface of a green sand mold

An instrument for determining the mold surface hardness shall measure the depth of penetration in to the mold

surface of a plunger having a load applied at a 90º angle to the mold surface

Grain Fineness Test

To Determine the Grain fineness number of the given sand sample

Theory

The base sand is a mixture of grains having a variety of shapes such as round, sub angular, angular, compound

grains.

Base sand is relatively free from any additives/binders

Depending on the average sizes of the grains the sand can be grouped into fine, medium, coarse grains

The shape and size of grains has a large influence on the permeability of sand mix as well as on the bonding action

The shape and size of grains determine the possibility of its applications in various types of foundry practices.

e.g.: fine grains results in good surface finish on the casting but gasses cannot escape out from the mould,

whereas coarse grains sand allows to escape the gasses but the surface finish of the casting will be rough, hence grain

size should be selected appropriately.

Sand Testing

The given size of the sand grain is designated by number called Grain fineness number, that indicates the average

size of the grains in the mixture

The size is determined by passing the sand through sieves having specific apertures which are measured in

microns.

The sieve numbers designates the pore size through which the sand grains may pass through it or retained

Average grain fineness number can be found by the equation FN = Q / P

where Q= (DxC) sum of product of % sand retained in sieves and corresponding multiplier

P = C = sum of % of sand retained in sieves

Sand Testing

Procedure

1.To carry out this test, a sample of dry sand weighing 50 / 100 grams, is placed on the top most sieve number & close the lid.

2.A set of standard testing sieves having standard meshes varying from 1700 till 53 are mounted on a mechanical shaker.

3.The above sample is shaked for about 15 minutes.

4.Weight of the sand retained on each sieve can be obtained.

Sand Testing

Sieve shaker

Observation

Sand used = Base sand; weight of sand = 50gms, time = 10 min

Calculation for grain Fineness number

Sl No Sieve No.(A)

Weight of sand retained (B)

% of sand retained

(C)

Multiplier (D) Product(D x C)

Cumulative of sand retained

123456789

1011

17008506004253002121501067553

PAN

00.21.17.33.1

21.38.05.22.90.30.1

00.42.2

14.66.2

42.616

10.45.80.60.2

5102030405070

100140200300

04

44438248

21301120104081212060

00.42.6

17.223.46682

92.498.298.899

c = 99 = 6016

Results: Grain fineness number of the given sand sample is 60.76

Calculations:

P= c = 99 Q = (CxD) = 6016

Avg GFN = Q / P = 60.76

Clay content Test

To Determine the % of clay present in the base sand

Materials required : Base sand. NaoH solution, Distilled water

Apparatus : Wash bottle, Measuring jar, Mechanical Stirrer & siphon tube

TheoryClay can be defined as those particles having less than 20 microns size.

Moulding sand may contain 2-50% of binding strength and plasticity

Clay consists of 2 ingredients

1. Fine silts

2. True clay.

Fine silt has no bonding power

True clay imparts the necessary binding strength to the moulding sand, thereby the mould doesn’t loose

its shape after ramming.

Clay can also be defined as those particles when mixed with water agitated and then made to settle.

Fails to settle down at the rate of 1/min

The particles of clay are of plate like form & have a very large surface area compared to its thickness and therefore

has very high affinity to absorb moisture

Clay is of mineral origin available in plenty on earth, it is made of alumina silicate.

Types of clay are – Mont Morillonite, kaolinite, & Illite

The first type is referred as Bentonite

ProcedureTake 50gms of base sand in wash bottle, and add 475ml of distilled water, and 25ml of NaoH solution to it

Using mechanical stirrer, stir the mixture for about 3 minutes, and add distilled water to make up the level to 6” height and stir the mixture again for about 2 min. Now allow the contents to settle down.

Siphon out 5” level of unclean water using standard siphon

Add distilled water again up to 6” height and stir the contents again for 10 min. After stirring allow the mixture to settle down for 5min.Siphon out 5” level of water using standard siphon

Repeat the above procedure for 3 times till the water becomes clear in the wash bottle

Transfer the wet sand from the bottle into tray and dry it in an oven at 110c to remove the moisture

Once the sand is dried, weight accurately using weighing instruments and note down the final value & find the clay %.

ObservationBase sand = 50gms

NaoH solution = 25ml

Distilled water = 475ml

Calculations

Weight of the base sand = w1 = 50 gms

Weight of the dry sand = w2 = 49.7 gms

% of clay content in base sand = (w1-w2) / w1 x 100

= (50-49.7) / 50

= 0.6 %

Results The % of clay contained in the given base sand is 0.6 %

To find the effect of water content, clay content on green permeability of sand

Equipment’s required : Permeability meter, balance, Stop watch, Sand rammer, Steel rule, measuring jar, Specimen tube stripper, Specimen tube base

Materials used Base sand, Clay and Water

Theory

Gases and water vapor are released in the mould cavity by the molten metal and sand.

If they do not find opportunity to escape completely through the mould, they will get entrapped and form gas

holes or pores in the casting

The sand must therefore be sufficiently porous to allow the gases and water vapor to escape out.

This property of sand is referred to as permeability.

Permeability Test

Permeability is a physical property of a sand mixture which allows gasses to pass through it easily

The AFS (American Foundry society) definition of permeability is the number obtained by passing 2000cc of air through a standard 2” x 2” specimen under a pressure of 10gm/cm2 for a given time in min.

The permeability number PN can be found out by the equation PN = (VH) / (PAT)

Procedure

Conduct the experiment in two parts.

1.In the first part, vary the water % keeping the clay % constant

2. In the second part vary the clay % and keep the water % constant

In both the cases keep the number of ramming of the specimen as three

Take the weighed proportions of sand and clay & dry mix them together for 3 min.

Then add the required proportions of water and wet mix for another 2 min, to get homogeneous sand mixture.

Take the total weight of the mixture

Fill the sand mixture ( Known weight: e.g. 150g/165g/170g) into the specimen tube and ram thrice using sand rammer.

Use the tolerance limit provided at the top end of the checking the specimen size.

If the top end of the rammer is within the tolerance limits, the correct specimen is obtained.

Now the prepared standard specimen is having a diameter 5.08cm & height 5.08cm

Place the standard specimen along with the tube in the inverted position on the rubber seal.

Operate the valve and start the stop watch simultaneously

When the zero mark on the inverted jar touches the top of water tank, note down the manometer reading, this gives

the pressure of air directly

Note down the time requires to pass 2000cc of air through the specimen. Calculate the permeability number by using

the formula.

PN = (VH) / (PAT) where

V = volume of air passing through the specimen = 2000cc

H = height of the specimen = 5.08cm ( standard value)

P = pressure as read from the manometer in gm/cm2

A = Area of the specimen = πd2/4, where d = 5.08cm ( Standard value)

T = time in min for 2000cc of air passed through the sand specimen

.

Direct scale reading: The permeability can also be determined by making use of graduated marker provided near the manometer.

Steps to be followed:

1.Coincide the graduations on the transparent scale with the miniscus of the manometer

2.Note the reading from the scale

3.This reading represents, the permeability numbers of sand.

Calculations1. Keeping the water constant at 5% & varying the clay

SL No % of sand % of clay % of water Time in seconds

Pressure

Indicated Calculated

1234

92919089

3456

5555

33313231

3.82.63.12.9

239.824373.126303.16334.52

2. Keeping the clay constant at 4% & varying the water

SL No % of sand % of clay % of water Time in seconds

Pressure

Indicated Calculated

1234

92919089

4444

4567

30283233

3.12.83.3

3.35

323.37383.59248.79272.03

Specimen Calculations

The permeability (PN) can be found by the eq PN = (VH) / (PAT)

V = volume = 2000cc

H = height of the specimen = 5.08cm

P = pressure of manometer

A = Area of the specimen = π d2 /4 = 20.27cm2

T = time in min for 2000cc of air passed through sand

PN = (VH)/(PAT) = (2000 x 5.08 x 60)/ (3.8 x 20.27 x 33) = 239.824

Moisture Content Test

To Determine the moisture content in the given sand sample.

Equipments and Materials

Electronic Balance, Oven with temperature 120degree

Theory

In clay bonded sand some moisture is essential to develop working strength.

The influence of moisture may be harmful if the proportion is not controlled within the definite limits.

The strength of a sand is also influenced by its moisture content.

It is therefore important to make certain that the sand contains the correct percentage of water

Procedure

Take the 150 gram sample of the sand.

Mix the water till it becomes in the paste form

Make it in the cylindrical shape.

Weight it

Put the sample in the oven for 10 minutes at 110 degree temperature

Take the sample out of the oven

Weight it again

The difference is the amount of moisture.

Observations

a)Initial weight of the sand sample with water = g

b) Final weight of the sand sample after drying = g

Calculations

The moisture content = Initial weight - Final weight

% Moisture content = (Initial weight - Final weight) / Initial weight

Results

The moisture content is---------------g

Compression Strength Test

To find the green compression strength of the given moulding sand at different % of clay & moisture


Base sand, clay & water, Balance, weighing pan, measuring jar, steel rule, specimen tube with base, stripper, sand ramming machine, compression shackles, Universal sand testing machine

Procedure

Conduct the experiment in two parts:

1. In the first case vary the clay % & keep water % constant. 2. In the second case vary the water % & keep the clay % constant.

Take weighed proportions of sand and clay and dry mix them together in a Muller for 3 min., then add water & wet mix for another 2 min., uniform mixture is obtained

compression shackles

Load LoadTestSpecimen

Fill the sand mixture in to the specimen tube and ram thrice using sand rammer.

Use the tolerance limit provided at the top end of the checking the specimen size, if the top end of the

rammer is within the tolerance limit, the correct specimen is obtained.

Remove the standard specimen using the stripper and place it between the shackles, which are fixed in the

universal sand testing machine.

Rotate the handle to actuate the ram (hydraulic pressure in the cylinder is built up to load the specimen

continuously till the specimen ruptures.

Now note down the compression strength value from the gauge and record the same

Conduct the experiment for the above said two cases and tabulate the results.

SL No % of sand % of clay % of water Compression Strength

gm/cm2 N/mm2

1234

92919089

3456

5555

1.41.62.64.2

0.137340.156960.2543

0.41297

CalculationsKeeping the water constant at 5% & varying the clay

SL No % of sand % of clay % of water Compression Strength

gm/cm2 N/mm2

1234

92919089

4444

4567

2.63.42.22.4

0.255060.33350.21580.2354

Keeping the clay constant 4% & varying water

Calculations(1.4 x 9.81) / 10 x 10 = 0.13734 N /mm2

Shear Strength Test

To find the green shear strength of the given moulding sand at different % of clay & moisture


Base sand, clay & water, Balance, weighing pan, measuring jar, steel rule, specimen tube with base, stripper, sand ramming machine, shear shackles, Universal sand testing machine

Load

Load

TestSpecimen

shear shacklesTheory

Shear strength is the ability of sand particles to resist the shear stress & stick together

Insufficient strength may lead to collapse of the sand in the mould or its partial destruction during handling the mould & core may also be damaged during the flow of molten metal in the mould cavity

The molding sand must possess sufficient strength to permit the mould to be formed to the desired shape & retain the shape even after the molten metal poured in to the mould

In shearing the rupture occurs parallel to the axis of the specimen

Procedure

Conduct the experiment in two parts

1. In the first case vary the clay % & keep water % constant.2. In the second case vary the water % & keep the clay % constant

Take 200gms of foundry sand ( mixture of sand, clay & water as specified)

Prepare the standard sample using these mixture as specified in procedure

Transfer the sand mixture into the tube & ram it thrice in the sand rammer to get the standard specimen. The top of the rammer rod should lie with in the tolerance limits.

Fix the shearing shackles to the universal sand testing machine

Remove the standard specimen from the tube using a stripper & load it on to the universal testing machine

Apply the hydraulic pressure by turning the handle of the testing machine continuously until the specimen ruptures.

Take the readings from the meter directly showing a shear strength of the specimen.

Calculations Keeping the water constant at 5% & varying the clay

SL No % of sand % of clay % of water Shear Strength

gm/cm2 N/mm2

1234

92919089

3456

5555

0.350.70.80.6

0.03430.06860.07840.0588

Keeping the water constant at 5% & varying the clay

SL No % of sand % of clay % of water Shear Strength

gm/cm2 N/mm2

1234

92919089

4444

4567

0.30.40.50.6

0.02940.03920.04900.0588

Bending Test

To find the green bending strength of the core sand using different types of binders; core oil binder &

sodium silicate binders


Base sand (silica sand), core oil, sodium silicate

Theory

A core is a compacted sand mass of a known shape

When a hollow casting or a complex control is required (to have a hole or internal shape through or blind depth) a core is used in the mould or a mould is created out of core

Core boxes are used for making cores. They are either made by a single or in two parts their classification is generally according to the shape of the core or the method of moving the core.

Split core box is very widely used and is made in two parts, which can be joined together by means of

dowels, to form a complete cavity for making the core

The purpose of adding the binder to the molding sand is to impart the strength & cohesiveness to the sand

to enable to retain its shape after core has been rammed.

Binders can be (a) organic binders – dextrine core oil (b) inorganic binders – sodium silicate, Bentonite

Procedure


1. using the core oil as a binder2. using sodium silicate as binder or any other binders

Make proper proportions of core sand & binder then mix together thoroughly

Assemble the core box and fill the sand & ram on to it

Place the core box under sand rammer & ram the sand thrice

Using a wooden piece top the core box gently from the sides. Remove the core box so that rammed core remains on a flat metal plate

Bake the specimen (which is on plate) for about 30 min at a temperature of 150-200c in an oven

Fix the bending shackles on to the sand testing machine then place the hardened specimen between the shackles

Apply the load gradually by turning the hand wheel of the testing machine. Note down the readings when the specimen breaks

Repeat the procedure for different % of binder & tabulate the readings

SL No % of sand % of Dextrine % of water Bending Strength

kg/cm2 N/mm2

1234

9493.593

92.5

11.52

2.5

5555

0.30.6

0.850.9

0.29430.58860.83380.8829

Observation

Bending strength of sand Varying content of organic binder ( Dextrine) water content 5%

Bending strength of sand Varying content of Inorganic binder ( Sodium silicate) & no water

SL No % of sand % of Sodium Silicate Bending Strength

kg/cm2 N/mm2

1234

97969594

3456

4.54

3.53

4.41453.9243.4332.943

Calculations

Bending strength = reading x 9.81 in kg/cm2= reading x 10/100 x 9.81 in N/mm2

= (4.5 x 10 x 9.81) / 100 = 4.41 N/mm2

Tensile Test

To determine the tensile strength of core sand using different types of binders, core oil binder & sodium silicate binders, etc.


Base sand (silica sand), core oil, sodium silicate, Split core box, sand rammer, oven, tensile shackles, Universal sand testing machine

Procedure


1. using the core oil as a binder2. using sodium silicate as binder or any other binders

Take proper proportions of core sand & binder then mix together thoroughly

Assemble the core box and fill the sand mixture into it

If the binder is sodium silicate, pass co2 gas for 5 seconds. The core hardens instantly & the core can be directly used

Fix the tensile shackles on to the sand testing machine and place the hardened specimen in the shackles

Apply the load gradually by turning the hand wheel of the testing machine. Note down the reading, when the specimen breaks

Repeat the procedure for different % of binder & tabulate the readings

Place the core box under sand rammer & ram the sand thrice

Using a wooden piece top the core box gently from the sides. Remove the core box so that rammed core remains on a flat metal plate

Bake the specimen (which is on plate) for about 30 min at a temperature of 150-200c in an oven

Observation

1. Water 5% constant for varying content of Dextrine binder (organic binder)

SLNo % of sand % of Dextrine % of water Tensile Strength

kg/cm2 N/mm2

1234

9493.593

92.5

11.52

2.5 5

1.62.63.23.4

1.56962.55063.13923.3354

2. No Water used for varying content of sodium silicate binder (Inorganic binder)

SLNo % of sand % of sodium silicate

Tensile Strength

kg/cm2 N/mm2

1234

9493.593

92.5

3456

1.72.6

1.752.9

1.66772.55061.7162.844

CalculationsTensile strength = Direct reading kg/cm2 x 9.81

= (reading x 10 x 9.81) / 100 N/mm2

Forging PracticeForging Practice

Outline

Introduction

Forging – Basic Principles

Forging – Terminology

Objectives of the forging lab

Forging – materials and equipment

IntroductionIntroduction

A metal is shaped by compressive forces

Oldest metal working process – 4000BC

Can be performed with a hammer and anvil

Typical forged products

Bolts

Rivets

Connecting rods

Forging is a Bulk Deformation Process in which the work is compressed between two dies.

According to the degree to which the flow of the metal is constrained by the dies.


FORGING TERMINOLOGIES

Hot forging

Plastically deforming an alloy at a temperature above its re-crystallization point

Open Die Forgings / Hand Forgings Made with repeated blows in an open die

The operator manipulates the work piece in the die.

Impression Die Forgings / Precision Forgings:

Are further refinements of the blocker forgings.

The finished part more closely resembles the die impression.

Cold working is metal forming performed at room temperature.

Advantages: better accuracy, better surface finish, high strength and hardness of the part, no heating is required.

Disadvantages: higher forces and power, limitations to the amount of forming, some material are not capable of cold working.

Warm working is metal forming at temperatures above the room temperature but below the recrystallization temperature.

Advantages: lower forces and power, more complex part shapes, no annealing is required.

Disadvantages: some investment in furnaces is needed.

Hot working involves deformation of preheated material at temperatures above the re crystallization temperature.

Advantages: big amount of forming is possible, lower forces and power are required, forming of materials with low ductility, no work hardening and therefore, no additional annealing is required.

Disadvantages: lower accuracy and surface finish, higher production cost, and shorter tool life.


Illustration of Simple forging Operation

Anvil

serves as a work bench to the blacksmith, where the metal to be beaten is placed.

made of cast or wrought iron with a tool steel face welded on

The flat top has two holes; the wider is called the hardy hole, where the square shank of the hardy fits.

The smaller hole is called the punch hole, used as clearance when punching holes in hot metal

ADVANTAGES AND DISADVANTAGES OF FORGING

DISADVANTAGES

High tool cost.

High tool maintenance.

Limitation in size and shape.

ADVANTAGES

Uniformity of qualities for parts subject to high stress

and loads.

No weight loss.

Close tolerance.

Less machining or no machining in some cases.

Smooth surface.

High speed of production.

Incorporation in welded structures, i.e., what can be

welded easily.

Forging OperationsForging Operations

Upsetting forging

Upset forging increases the diameter of the work piece by compressing its length.

A few examples of common parts produced using the upset forging process are engine valves, couplings, bolts, screws, and other fasteners.

Bending Operations

Bending is very common forging operation. It is an operation to give a turn to metal rod or plate. This is required for those which have bends shapes.

Drawing

This is the operation in which metal gets elongated with a reduction in the cross sedation area. For this, a force is to be applied in a direction perpendicular to the length axis.

Fullering

It a similar to material cross-section is decreased and length increased.

To do this; the bottom fuller is kept in angle hole with the heated stock over the fuller .

The top fuller is then kept above the stock and then with the sledge hammer, and the force is applied on the top fuller.

Edging

It is a process in which the metal piece is displaced to the desired shape by striking between two dies

Edging is frequently as primary drop forging operation.

Punching

It is a process of producing holes in motel plate is placed over the hollow cylindrical die.

By pressing the punch over the plate the hole is made.

foundry & forging ppt

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