SAND CASTING

EXHAUST MANIFOLD

PDM 6 GROUP 2

IZZAT HAIZA

ALIF FAIRUZ

History The Assyrian king Sennacherib (704-

681BC) cast massive bronzes of up to 30 tonnes, and claims to have been the first to have used clay moulds rather than the 'lost-wax' method.

In 1912, the sand slinger was invented by the American company Beardsley & Piper.

In 1912, the first sand mixer with individually mounted revolving plows was marketed by the Simpson Company.

In 1915, the first experiments started with bentonite clay instead of simple fire clay as the bonding additive to the molding sand. This increased tremendously the green and dry strength of the molds.

In 1918, the first fully automated foundry for fabricating hand grenades for the U.S. Army went into production.

Part : Exhaust Manifold in CarCasting Process (Sand Casting)

1. Study all type of casting available in the industry. List all of them

2. Explain the function of exhaust manifold.3. Study the suitable material to produce exhaust manifold.4. Explain in detail about the casting process selected.5. Explain the advantages and disadvantages of the

casting process selected.6. Explain defects that occur from the selected.7. Explore another type of manufacturing process to

produce exhaust manifold.8. Make comparison between both types of the

manufacturing process.

Haiza Will explain about question no 1 and 2 .

^_^

All type of casting in industry 1 . Type of casting available In industry 2 . Explain the function of exhaust

manifold

All type of Casting : Sand casting Permanent mold casting Investment casting Lost foam casting High pressure die casting Centrifugal casting Glass casting

Sand Casting Sand casting, also known as sand

molded casting, is a metal casting process characterized by using sand as the mold material. Over 70% of all metal castings are produced via a sand casting process.

Matchplate sand molding The principle of the matchplate,

meaning pattern plates with two patterns on each side of the same plate, was developed and patented in 1910, fostering the perspectives for future sand molding improvements.

> The method alike to the DISA's (DISAMATIC) vertical moulding is flaskless.

> Its great advantage is inexpensive pattern tooling, easiness of changing the molding tooling.

Permanent mold casting

Permanent mold casting is metal casting process that employs reusable molds ("permanent molds"), usually made from metal.

The most common process uses gravity to fill the mold, however gas pressure or a vacuum are also used.

A variation on the typical gravity casting process, called slush casting, produces hollow castings.

Common casting metals are aluminum, magnesium, and copper alloys. Other materials include tin, zinc, and lead alloys and iron and steel are also cast in graphite molds.

The Process Gravity process Mold Slush Low pressure Vaccum

Investment casting Investment casting is an industrial process based on

and also called lost-wax casting, one of the oldest known metal-forming techniques. 

From 5,000 years ago, when beeswax formed the pattern, to today’s high-technology waxes, refractory materials and specialist alloys, the castings allow the production of components with accuracy, repeatability, versatility and integrity in a variety of metals and high-performance alloys. 

Lost-foam casting is a modern form of investment casting that eliminates certain steps in the process.

The process is generally used for small castings, but has been used to produce complete aircraft door frames, steel castings of up to 300 kg (660 lbs) andaluminium castings of up to 30 kg (66 lbs).

It is generally more expensive per unit than die casting or sand casting, but has lower equipment costs.

It can produce complicated shapes that would be difficult or impossible with die casting, yet like that process, it requires little surface finishing and only minor machining.

Lost-foam Casting Lost-foam casting (LFC) is a type

of evaporative-pattern casting process that is similar to investment casting except foam is used for the pattern instead of wax.

This process takes advantage of the low boiling point of foam to simplify the investment casting process by removing the need to melt the wax out of the mold.

Die Casting Die casting is a metal casting process that is

characterized by forcing molten metal under high pressure into a mold cavity.

The mold cavity is created using two hardened tool steel dies which have been machined into shape and work similarly to an injection mold during the process.

Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter and tin based alloys.

Die castings are characterized by a very good surface finish (by casting standards) and dimensional consistency.

Two variants are pore-free die casting, which is used to eliminate gas porosity defects; and direct injection die casting, which is used with zinc castings to reduce scrap and increase yield.

Centrifugal Casting Centrifugal casting is a metallurgical

manufacturing process by casting that may refer to either:

Centrifugal casting (industrial), on an industrial scale

Centrifugal casting (silversmithing), for a smaller scale

A related process is spin casting

Glass Casting Glass casting is the process in

which glass objects are cast by directing molten glass into a mould where it solidifies.

Modern cast glass is formed by a variety of processes such as kiln casting, or casting into sand, graphite or metal moulds.

Function of Exhaust Manifold Exhaust manifolds are generally simple cast iron or

stainless steel units which collect engine exhaust from multiple cylinders and deliver it to the exhaust pipe.

For many engines, there are aftermarket tubular exhaust manifolds known as headers in US English, as extractor manifolds in British and Australian English, and simply as "tubular manifolds" in UK English.

These consist of individual exhaust headpipes for each cylinder, which then usually converge into one tube called a collector.

Headers that do not have collectors are called 'zoomie headers'.

Another form of modification used is to insulate a standard or aftermarket manifold.

This decreases the amount of heat given off into the engine bay, therefore reducing the intake manifold temperature. There are a few types of thermal insulation but three are particularly common:

Ceramic paint is sprayed or brushed onto the manifold and then cured in an oven.

These are usually thin, so have little insulatory properties; however, they reduce engine bay heating by lessening the heat output via radiation.

A ceramic mixture is bonded to the manifold via thermal spraying to give a tough ceramic coating with very good thermal insulation.

This is often used on performance production cars and track-only racers

Exhaust wrap is wrapped completely around the manifold.

Although this is cheap and fairly simple, it can lead to premature degradation of the manifold.

the function of an exhaust manifold on a gasoline or diesel engine is to expel the burnt fuel from

the combustion chamber of each piston out through the exhaust pipe after each combustion stroke of

the piston has been completed.

IzzatWill explain :3. Suitable material to produce exhaust manifold.4. Detail about casting process selected.

Suitable material to produce exhaust manifold Materials used for exhaust piping, mufflers, and other

exhaust system components consist mainly of ferrous alloys.

Aluminum alloys are sometimes used as a coating on ferrous alloys to impart additional corrosion resistance.

In some cases, nonferrous nickel and titanium alloys are used in exhaust system components in especially demanding and/or high performance applications.

Ceramics have also seen limited use in exhaust systems to take advantage of their insulating properties.

Ceramics and specialized metal alloys, albeit with different compositions and properties than those used in piping systems, are also commonly used in substrates for aftertreatment devices—ceramic and metallic catalyst substrates and particulate filter substrates.

These materials are discussed in more detail in the papers dealing with aftertreatment.

Ferrous alloys are based on iron-carbon alloys and include carbon steel, alloy steels, stainless steel and cast iron. Alloying elements are added to:

Provide solid solution strengthening of ferrite,

Cause the precipitation of alloy carbides rather than cementite Fe3C,

Improve corrosion resistance and other special characteristics.

The varieties of stainless steel available, two that are important exhaust system materials are: Ferritic stainless steel, and ; Austenitic stainless steel. Ferrous alloys can contain three

important grain structures: ferrite, austenite and martensite. In ferrite, the iron atoms form a body centered cubic (BCC or α-iron) structure with iron atoms at each corner of a cube and one in the center of the cube, Figure 1.

 Austenite is a face centered cubic (FCC or γ-iron) structure with iron atoms at each corner and on the center of each face of a cube. Interstitial holes in the FCC structure allow austenite to accommodate a greater number of carbon atoms, up to 2.11% by weight, than the BCC structure of ferrite which can accommodate up to 0.0218% carbon.

Austenite can be transformed into martensite, a very hard and brittle grain structure that is not normally used in exhaust piping systems.

4 . Explain in detail about the casting process selected ( sand casting ) Sand casting, also known as sand molded

casting, is a metal casting process characterized by using sand as the mold material.

The term "sand casting" can also refer to an object produced via the sand casting process.

Sand castings are produced in specialized factories called foundries.

Over 70% of all metal castings are produced via a sand casting process.[

Sand casting is relatively cheap and sufficiently refractory even for steel foundry use. In addition to the sand, a suitable bonding agent (usually clay) is mixed or occurs with the sand.

The sand is typically contained in a system of frames or mold boxes known as a flask.

The mold cavities and gate system are created by compacting the sand around models, or patterns, or carved directly into the sand.

Basic ProcessThere are six steps in this process: Place a pattern in sand to create a mold. Incorporate the pattern and sand in a

gating system. Remove the pattern. Fill the mold cavity with molten metal. Allow the metal to cool. Break away the sand mold and remove

the casting.

ComponentPatterns Builds a pattern of the object to be

produced, using wood, metal, or a plastic such as expanded polystyrene. Sand can be ground, swept orstrickled into shape

The metal to be cast will contract during solidification, and this may be non-uniform due to uneven cooling.

Different scaled rules are used for different metals, because each metal and alloy contracts by an amount distinct from all others

Patterns also have core prints that create registers within the molds into which are placed sand cores.

Molding box and materialsMolding box and materials A multi-part molding box (known as a casting

flask, the top and bottom halves of which are known respectively as the cope and drag) is prepared to receive the pattern.

Molding boxes are made in segments that may be latched to each other and to end closures

 The sand is packed in through a vibratory process called ramming, and in this case, periodically screeded level.

The surface of the sand may then be stabilized with a sizing compound.

The pattern is placed on the sand and another molding box segment is added.

Additional sand is rammed over and around the pattern.

Finally a cover is placed on the box and it is turned and unlatched, so that the halves of the mold may be parted and the pattern with its sprue and vent patterns removed.

Chills To control the solidification structure of the

metal, it is possible to place metal plates, chills, in the mold.

The associated rapid local cooling will form a finer-grained structure and may form a somewhat harder metal at these locations.

In ferrous castings, the effect is similar to quenching metals in forge work..

CoresCores To produce cavities within the casting—such as

for liquid cooling in engine blocks and cylinder heads—negative forms are used to produce cores.

Usually sand-molded, cores are inserted into the casting box after removal of the pattern. Whenever possible, designs are made that avoid the use of cores, due to the additional set-up time and thus greater cost.

Design requirements The part to be made and its pattern must be designed to accommodate each stage of the process, as it must be possible to remove the pattern without disturbing the molding sand and to have proper locations to receive and position the cores. 

 A slight taper, known as draft, must be used on surfaces perpendicular to the parting line, in order to be able to remove the pattern from the mold.

 The sprue and risers must be arranged to allow a proper flow of metal and gasses within the mold in order to avoid an incomplete casting.

Should a piece of core or mold become dislodged it may be embedded in the final casting, forming a sand pit, which may render the casting unusable

Gas pockets can cause internal voids. These may be immediately visible or may only be revealed after extensive machining has been performed.

For critical applications, or where the cost of wasted effort is a factor, non-destructive testing methods may be applied before further work is performed.

Green Sand These expendable molds are made of wet sands that

are used to make the mold's shape. 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), 75 to 85%, or olivine, or staurolite, or graphite.

bentonite (clay), 5 to 11% water, 2 to 4% inert sludge 3 to 5% anthracite (0 to 1%)

Another process of Sand casting Horizontal sand flask molding In the first automatic horizontal flask lines the sand was

shot or slung down on the pattern in a flask and squeezed with hydraulic pressure of up to 140 bars.

The subsequent mold handling including turn-over, assembling, pushing-out on a conveyor were accomplished either manually or automatically. In the late fifties hydraulically powered pistons or multi-piston systems were used for the sand compaction in the flasks.

 This method produced much more stable and accurate molds than it was possible manually or pneumatically

Aliff Afeqi

Will guide you about

Advantages and disadvantages of casting process (Sand Casting) . . .And Defect that Occur the process. ^_^

Advantages and disadvantages of casting process selected

Advantages

Advantages: 1) Low capital investment

means that short production runs are viable;

2) Use of sand cores allows fairly complex shapes to be cast;

3) Large components can be produced;

4) Suitable for small banch production( small production rates)

Disadvantages Disadvantages: 1) The process has a high unit

cost, as it is labor intensive and time consuming;

2) The sand mold leaves bad surface finish, due to sand indentation and oxidizing medium, which often requires further processing;

3) Cannot make thin sections; 4) Not suitable for mass

production, oftenly used to produce few number of products compared with other casting proccesses which produce thousands and millions.

Defect that occur sand casting Production of castings involves a large number of steps

including casting design, pattern making, moulding, melting, pouring, shake out, fettling, inspection and finishing.

It is not uncommon for one or more of these steps to be performed unsatisfactorily due to use of defective material or equipment, carelessness of the operator or lack of skill.

Such unsatisfactory operations result in a defective casting which may be rejected at the final stage.

Since reclamation of defective castings is often costly and sometimes outright impossible, care should be taken to avoid the occurrence of the defects in the first instance.

It is therefore necessary to understand the various defects that occur in sand castings and the main factors that are responsible for their occurrence.

Some of the common defects are described below.

1. Open Blows and Blow Holes 2. Pin Hole Porosity 3. Entrapped Air and other gases 4. Cracked Casting 5. Bent or Twisted Casting 6. Dropped Mould 7. Fusion 8. Swell 9. Run out

10. Mismatch 11. Mis-run and Cold Shut 12. Shrinkage-Faults 13. Rat Tail and Buckles 14. Core Shift 15. Inclusions 16. Cuts and Washes 17. Metal penetration 18. Hard Spots 19. Scabs 20. Hot tears

Shrinkage Faults:

Shrinkage faults are faults caused by improper directional solidifications, poor gating and risering design and inadequate feeding.

Solidification leads to volumetric contraction which must be compensated by feeding. If this compensation is inadequate either surface shrinkage or internal shrinkage defects are produced making the casting weaker.

Shrinkage faults can be reduced by providing proper gating system, pouring at correct temperature and taking care of directional solidification.

Rat Tail and Buckles: Rat tails and buckles are caused by the expansion

of a thin outer layer of moulding sand on the surface of the mould cavity due to metal heat.

A rat tail is caused by depression of a part of the mould under compression which appears as an irregular line on the surface of the casting.

A buckle is a more severe failure of the sand surface under compression.

The mould must provide for proper expansion instead of forming compressed layers to avoid this defect.

Core Shift:

A core shift results from improper support or location of a core.

It results in a faulty cavity or hole in the casting.

It can be reduced by providing proper support for cores and correct alignment with the mould.

Sand casting Sand casting has many defects that can

occur due to the mold failing. The mold usually fails because of one of two reasons: the wrong material is used or it is improperly rammed.

The first type is mold erosion, which is the wearing away of the mold as the liquid metal fills the mold.

This type of defect usually only occurs in sand castings because most other casting processes have more robust molds.

The castings produced have rough spots and excess material.

Fairuz Will ending the presentation with explain about :

7) Explain another type manufacturing process to produce Exhaust Manifold8) Make comparision between both type of manufacturing process,

Die CastingDie casting is a metal casting process that is characterized by : forcing molten metal under high pressure into

a mold cavity. The mold cavity is created using two hardened tool

steel dies which have been machined into shape and work similarly to an injection mold during the process.

Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter and tin based alloys.

Depending on the type of metal being cast, a hot- or cold-chamber machine is used.

The casting equipment and the metal dies represent large capital costs and this tends to limit the process to high volume production.  

Die castings are characterized by a very good surface finish (by casting standards) and dimensional consistency.

Process

The following are the four steps in traditional die casting, also known as high-pressure die casting, these are also the basis for any of the die casting variations,die preparation,filling,ejection, and shakeout.

The dies are then closed and molten metal is injected into the dies under high pressure; between 10 and 175 megapascals (1,500 and 25,400 psi)

Finally, the shakeout involves separating the scrap, which includes the gate, runners, sprues and flash, from the shot.

Comparision:Sand Casting

Sand CastingAdvantages: 1) Low capital investment

means that short production runs are viable;

2) Use of sand cores allows fairly complex shapes to be cast;

3) Large components can be produced;

4) Suitable for small banch production( small production rates)

Die CastingAdvantages of die casting are : Cost per unit is minimum hence

economical. It requires less floor space as

compared to other casting processes.

Rate of production is high. 75 to 150 casts per hour in cold chamber and 300 to 350 casts per hour in hot chamber process.

High surface finish is obtained and often no further finishing is required.

ComparisionSand Casting

Disadvantages: 1) The process has a high

unit cost, as it is labor intensive and time consuming;

2) The sand mold leaves bad surface finish, due to sand indentation and oxidizing medium, which often requires further processing;

3) Cannot make thin sections;

4) Not suitable for mass production, oftenly used to produce few number of products compared with other casting proccesses which produce thousands and millions.

Die Casting

Disadvantages : 1) All metals and

alloys can not be cast. 2) The cost of

machines, dies and other equipment used is high.

3) Not economical for small quantity production.

4) Heavy casting cannot be cast.

Sand casting : Over 70% of all metal castings are produced via a sand casting process.

Die Casting : . Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter and tin based alloys.

End of PresentationAbout Sand Casting.

From group 2 :

- Izzat - Haiza- Aliff Afeqi- Fairuz

Assalamualaikum ,

Thanks to Sir Azam

And friend ^_^

THE END