MOISTURE CONTENT TESTMoisture is the property of the moulding sand defined as the amount of water present in the moulding sand. Low moisture content in the moulding sand does not develop strength properties. High moisture content decreases permeability.

Procedure:1. 20 to 50 gms of prepared sand is placed in the pan and is heated by an infrared heater bulb for 2 to 3 minutes.

2. The moisture in the moulding sand is thus evaporated.

3. Moulding sand is taken out of the pan and reweighed.

4. The percentage of moisture can be calculated from the difference in the weights, of the original moist and the consequently dried sand samples.

Observation and Calculation:W1-Weight of the sand before drying= gms

W2-Weight of the sand after drying= gms

Percentage of moisture content = (W1-W2) / (W1) % =

Result:

The percentage of moisture content obtained is = gms

CLAY CONTENT TESTClay influences strength, permeability and other moulding properties. It is responsible for bonding sand particles together.

1. Small quantity of prepared moulding sand was dried

2. Weigh 50 100 gms of dry moulding sand and transfer into wash bottle.

3. Add 475cc of distilled water + 25cc of a 3% NaOH.

4. Agitate this mixture about 10 minutes with the help of sand stirrer.

5. After the sand etc., has settled for about 10 minutes, Siphon out the water from the wash bottle.6. Fill the wash bottle with water up to the marker for the next 2 trials.

7. Remove and dry the settled down sand in an oven.

8. The clay content can be determined from the difference in weights of the initial and final sand samples.

Observation and Calculation:

W1-Weight of the sand before drying= gms

W2-Weight of the sand after drying= gms

Percentage of moisture content = (W1-W2) / (W1) %

Result:

The percentage of clay content obtained is = gmsSIEVE ANALYSIS (or) GRAIN FINENESS TEST

The grain size, distribution, grain fitness are determined with the help of the fitness testing of moulding sands. The apparatus consists of a number of standard sieves mounted one above the other, on a power driven shaker.

The shaker vibrates the sieves and the sand placed on the top sieve gets screened and collects on different sieves depending upon the various sizes of grains present in the moulding sand.

The top sieve is coarsest and the bottom-most sieve is the finest of all the sieves. In between sieve are placed in order of fineness from top to bottom.

Procedure

1. Sample of dry sand (clay removed sand) placed in the upper sieve

2. Sand is vibrated for definite period

3. The amount of same retained on each sieve is weighted.

4. Percentage distribution of grain is computed.

Tabulation and ObservationPERMEABILITY TESTThe quantity of air that will pass through a standard specimen of the sand at a particular pressure condition is called the permeability of the sand.

Following are the major parts of the permeability test equipment:

1. An inverted bell jar, which floats in a water.

2. Specimen tube, for the purpose of hold the equipment

3. A manometer (measure the air pressure)

Procedure

1. The air (2000cc volume) held in the bell jar is forced to pass through the sand specimen.

2. At this time air entering the specimen equal to the air escaped through the specimen

3. Take the pressure reading in the manometer.

4. Note the time required for 2000cc of air to pass the sand

5. Calculate the permeability number

6.Permeability number (N) = ((V x H) / (A x P x T))Observation

V-Volume of air (cc) =

H-Height of the specimen (mm) =

A-Area of the specimen (mm2) =

P-Air pressure (gm / cm2) =

T-Time taken by the air to pass through the sand (seconds) =STRENGTH TESTMeasurements of strength of moulding sands can be carried out on the universal sand strength testing machine. The strength can be measured in compression, shear and tension.

The sands that could be tested are green sand, dry sand or core sand. The compression and shear test involve the standard cylindrical specimen that was used for the permeability test.

GREEN COMPRESSION STRENGTHGreen compression strength or simply green strength generally refers to the stress required to rupture the sand specimen under compressive loading. The sand specimen is taken out of the specimen tube and is immediately (any delay causes the drying of the sample which increases the strength) put on the strength testing machine and the force required to cause the compression failure is determined. The green strength of sands is generally in the range of 30 to 160 KPa.

GREEN SHEAR STRENGTHWith a sand sample similar to the above test, a different adapter is fitted in the universal machine so that the loading now be made for the shearing of the sand sample. The stress required to shear the specimen along the axis is then represented as the green shear strength. It may vary from 10 to 50 KPa.

MOULD HARDNESS TESTHardness of the mould surface can be tested with the help of an indentation hardness tester. It consists of indicator, spring loaded spherical indenter.

INTRODUCTION TO FOUNDRYAfoundryis afactorywhich producesmetal castingfrom eitherferrousornon-ferrousalloys. Metals are turned into parts by melting the metal into a liquid, pouring the metal in a mold, and then removing the mold material or casting. The most common metal alloys processed arealuminiumand cast iron. However, other metals, such assteel,magnesium,copper,tin, and zinc,can be processed.

Process:In the casting process a pattern is made in the shape of the desired part. This pattern is made out of wood, plastic or metal. Simple designs can be made in a single piece or solid pattern. More complex designs are made in two parts, called split patterns. A split pattern has a top or upper section, called a cope, and a bottom or lower section called a drag. Both solid and split patterns can have cores inserted to complete the final part shape. Where the cope and drag separates is called the parting line. When making a pattern it is best to taper the edges so that the pattern can be removed without breaking the mold.

The patterns are then packed in sand with a binder, which helps to harden the sand into a semi-permanent shape. Once the sand mold is cured, the pattern is removed leaving a hollow space in the sand in the shape of the desired part. The pattern is intentionally made larger than the cast part to allow for shrinkage during cooling. Sand cores can then be inserted in the mold to create holes and improve the casting's net shape. Simple patterns are normally open on top and melted metal poured into them. Two piece molds are clamped together and melted metal is then poured in to an opening, called a gate. If necessary, vent holes will be created to allow hot gases to escape during the pour. The pouring temperature of the metal should be a few hundred degrees higher than the melting point to assure good fluidity, thereby avoiding prematurely cooling, which will cause voids and porosity. When the metal cools, the sand mold is removed and the metal part is ready for secondary operations, such as machining and plating. Sand casting is the least expensive of all of the casting processes.AdvantagesThe finished product of a foundry can be more geometrically complex than the product of arolling,forging, ormachiningprocess like milling or turning. The mechanical properties of castings are equal in every direction, which makes them more suitable for multi-directional loading conditions. A foundry is the original way to producenear net shapeparts. Castings frequently do not require or only require a little machining to create the finished part.

Steps involved

1:- MeltingMelting is performed in afurnace. Virgin material, external scrap, internal scrap, and alloying elements are used to charge the furnace.The process includes melting the charge, refining the melt, adjusting the melt chemistry and tapping into a transport vessel. Refining is done to remove deleterious gases and elements from the molten metal. Material is added during the melting process to bring the final chemistry within a specific range specified by industry and/or internal standards.During the tap, final chemistry adjustments are made.Furnace:Modern furnace types includeElectric Arc Furnaces(EAF),Induction Furnaces,Cupolas, andcrucible furnaces, Reverberatory. Furnace choice is dependent on the alloy system and quantities produced. For ferrous materials, EAFs, cupolas, and induction furnaces are commonly used. Reverberatory and crucible furnaces are common for producing aluminum castings.The furnace must be designed for temperatures over 3600 Celsius. The fuel used to reach these high temperatures can be electricity or coke.2:-MoldingPrior to pouring acasting, the foundry produces a mold. The molds are constructed by several different processes dependent upon the type of foundry, metal to be poured, quantity of parts to be produced, size of thecastingand complexity of thecasting. These mold processes include:

Sand casting- Green or Resin bonded sand mold.

Lost Foam casting- Polystyrene pattern with a mixture of ceramic and sand mold.

Investment (lost wax) casting- Wax or similar sacrificial pattern with a ceramic mold

Plaster casting- Plaster mold

V-process casting- Vacuum is used in conjunction with thermoformed plastic to form sand molds. No moisture, clay or resin is needed for sand to retain shape.

Die casting- Metal mold.

Billet (ingot) casting- Simple mold for producing ingots of metal normally for use in other foundries.

3:- PouringIn a foundry, molten metal is poured intomolds. Pouring can be accomplished with gravity, or it may be assisted with a vacuum or pressurized gas. Many modern foundries use robots or automatic pouring machines for pouring molten metal. Traditionally, molds were poured by hand usingladles.

4:-ShakeoutThe solidified metal component is then removed from its mold. Where the mold is sand based, this can be done by shaking or tumbling. This frees the cast component, which will still be attached to the metal runners and gates - which are the channels through which the molten metal travelled to reach the component itself.5:-DegatingDegating is the removal of the heads, runners, gates, andrisersfrom the casting. Runners, gates, and risers may be removed using cutting torches, band saws or ceramic cutoff blades. For some metal types, and with some gating system designs, the sprue, runners and gates can be removed by breaking them away from the casting with a hammer or specially designed knockout machinery. Risers must usually be removed using a cutting method but some newer methods of riser removal use knockoff machinery with special designs incorporated into the riser neck geometry that allow the riser to break off at the right place.

6:-Surface cleaningAfter Degating, sand or other molding media may adhere to the casting. To remove this the surface is cleaned using a blasting process. This means a granular media will be propelled against the surface of the casting to mechanically knock away the adhering sand. The media may be blown with compressed air, or may be hurled using a shot wheel. The media strikes the casting surface at high velocity to dislodge the molding media (for example, sand) from the casting surface. Numerous materials may be used as media, including steel, iron, other metal alloys, aluminum oxides, glass beads, walnut shells, baking powder or numerous other materials. The blasting media is selected to develop the color and reflectance of the cast surface. Terms used to describe this process include cleaning, blasting, shotblasting and sand blasting of castings.7:-FinishingThe final step in the process usually involves grinding, sanding, or machining the component in order to achieve the desired dimensional accuracies, physical shape and surface finish.

Removing the remaining gate material, called a gate stub, is usually done using agrinderorsanding. These processes are used because their material removal rates are slow enough to control the amount of material. These steps are done prior to any final machining.

After grinding, any surfaces that requires tight dimensional control are machined. Many castings are machined inCNC millingcenters. The reason for this is that these processes have better dimensional capability and repeatability than many casting processes. However, it is not uncommon today for many components to be used without machining.INTRODUCTION TO FORGING

A process of working metal to a finished shape by hammering or pressing and is primarily a "hot" operation. It is applied to the production of shapes either impossible or too costly to make by other methods or needing properties not obtainable by casting. Categories of forgings include Hammer, Press, Drop or Stamping.Forging dates back to ancient times and was associated with the village blacksmith. Virtually all ductile metals may be forged by first preheating the work piece to a forging temperature. The work piece can be a billet, a wrought bar, a cast or sintered ingot etc. The forging process can then be completed by hammering the work piece to the desired shape.

Forging has a marked beneficial effect on the metals being shaped. Their toughness and strength are improved because the process results in a beneficial orientation of the metal grain structure. The repeated hot working causes the metal to become more dense and the grain "flow lines" to follow the contour of the final component.

There are a number of variations of the forging process a number are listed below.1) Open Die/hammer or smith forging2) Drop forging. (Closed die)3) Press forging4) Upset forging5) Swaging6) Roll forging.

Open Die ForgingOpen die (smith forgings) are made by using steam or air hammers or presses in conjunction with blacksmith tools or flat type dies. There is little lateral confinement of the work piece. The desired shape is obtained by manipulating the workpiece between blows.This process employs low cost tooling, is relatively simple, but has less control in determining grain flow, mechanical properties and dimensions than other forging methods. This process can only be carried out by skilled operators.With this process only parts of simple shape can be made.However depending on the size of he hammer used forgings of up to 90 te can be made.

Closed Die ForgingThis process is based on hammering the work pieces into into the desired shape by means of closing dies.The hammering or pressing is performed, respectively, by a mechanical or hydraulic press. Small and medium sized forgings are generally made in presses ranging in capacity from 500 to 10000 te.Closed die forgings have good dimensional accuracy, with improved mechanical properties compared to open die forgings. The process has good reproducibility and rapid production rates are possible. The initial cost of tooling is very high.

Closed die forging can be used to produce parts from a few grammes to 100 kg.

Press ForgingIn this process a slow squeezing action is used to form the metal. The slow squeezing action penetrates the entire workpiece allowing the process to be used for the forging of large objects.Press forges are made in sizes of up to 50,000 te. Upt to 15000 te the presses may be mechanical or hydraulic.The larger presses are always hydraulically powered.

Press forgings may use either open dies or closed dies. the latter are used for smaller components which may be fully formed in one forging stroke.

This process may is used for the production of large objects train wheels and aircraft landing gear parts.Upset ForgingThis process uses barstock which is heated at the end which is being forged. The bar is grippedin the fixed half of a die so that the length of material being forged projects. The forging blow is delivered by a moving die. Simple shapes are produced in a single stage but more complicated shapes require multiple stages.The process, if carried out cold is called cold heading

Swaging

Swaging is the forging method used for sizing, pointing, tapering, and otherwise shaping of the ends of rods or tubing.Rolling

Rolling is the most important metal working process and can be performed on either hot or cold metal. Material is passed between cast of forged steel rolls which compress it and move it forward. Rolling is a economical method of deformation if metal is required in long lengths of uniform cross section. Normal rolling achieves thickness reduction of about 2:1.

Slabs and bloomsIngots are first rolled into either rectangular slabs or square blooms which are produced as intermediate stages. In this rolling process the ingots are passed through the plain rolls repeatedly in one direction and then in the reverse direction at each stage the rolls are brought closer together. If square blooms are required the material is rotated through 90obetween rolling operations.

Plates Strips and Sections

The rolling process can be used to produce plates, strips and rolled sections including channels, Universal Columns angles sections etc. The plates and strips are generally formed using plain rolls. The rolls can bow which results in the plate being thicker at the middle. The rolls can be backed up in four high roll arrangements. with additional rolls to reduce this tendency..

Planetary rolling mills

Small diameter rollers are more effective than large ones in conveying rolling forces to deforming metal. Planetary mills take advantage of this principle. This process can achieve thickness reductions of up to 25:1