PART-A (10x2=20)

Answer All Questions

1. List the different pattern material used

Some materials used for making patterns are: wood, metals and alloys, plastic, plaster of Paris,
plastic and rubbers, wax, and resins.
2. Define weldability.
Weldability is the capacity of a material to be welded under fabrication conditions and to perform
satisfactorily in the intended service
3. Define the term extrusion ratio.
Extrusion ratio is defined as the starting cross-sectional area divided by the cross-sectional area of
the final extrusion.
4. Mention different types of shape rolling operation.
Blooming rolls
Edging rolls
Ring Rolling
Thread Rolling
5. What is spring back effort and how it
Spring back is defined as the movement of the metal to resume its original position causing a
decrease in bent angle. After the applied force is withdrawn. It can be avoided by,
Over stretching using V- Coining the edges.
6. What is super plastic forming operation
Very fine grains are obtained within certain temperature ranges & at low strain rates. These alloys
can be formed into complex shapes by super plastic forming. Zinc, Aluminum
and Titanium has super plastic behavior.
7. When do you prefer shaping process for generating a gear?
Gear shaping is preferred for operations like cutting gear segments, cutting, spur gear,
herring- bone gears, splines and sprockets etc., of gear shaping over other diameter
8. Give some applications of broaching.
By internal broaching, splined holes, key ways internal gear seration, square and hexagonal
holes and holes with different c are broached. By surface broaching, flat surface and surface
different contour, external splines
9. List any four work holding devices.
1.Chucks, 2) Centres, 3) Face plate, 4) Angle plate.
10. What is tool signature?
The various angles of tools are mentioned in a numerical number in
particular o rder. That order is known as tool signature.

PART-B (5 x 16 = 80)

11.A. Elaborate the steps in the preparation of green sand moulding with neat sketch.
Green Sand Molding
Green sand is the most diversified molding method used in metal casting operations.
The process utilizes a mold made of compressed or compacted moist sand. The term
"green" denotes the presence of moisture in the molding sand. The mold material
consists of silica sand mixed with a suitable bonding agent (usually clay) and
moisture.
Advantages
Most metals can be cast by this method.
Pattern costs and material costs are relatively low.
No Limitation with respect to size of casting and type of metal or alloy used
Disadvantages

11.B. Explain the working of MIG welding process with neat sketch
Metal-Inert-Gas Arc Welding (MIG)

Principle
MIG make use of the high heat produced by the electric arc between the
consumable electrode and material to be welded.
Gas Metal Arc Welding is a shielded metal arc process.

 The electrode is continuously fed through a gun.

The current ranges from 100 to 400 A depending upon the diameter of the
wire.
The speed of melting of the wire may be up to 5m/min.
Usually constant voltage DC machine is used for MIG Welding.
Welding Gun is either water cooled or air cooled.
Welding wire is often bare.
CO, argon or argon helium mixtures are often used as shielding gases.
Shielding is done to prevent contamination of weld.
Applications :
Used for welding of carbon, silicon and low alloy steels, stainless steels,
aluminum, magnesium, copper, nickel and their alloys, titanium etc.
Used for manufacture of refrigerator parts.
Used in industries like aircraft, automobile, pressure vessel and ship building.
12.A. Enumerate and explain the different operations carried out in the forging.
Basic forging operations employed in giving required shape to the work piece are described below:
(i)

Upsetting: It is the process of increasing the cross-section at expense of the length of the work piece.

(ii)

Drawing down: It is the reverse of upsetting process. In this process length in increased and the crosssectional area is reduced.

(iii)

Cutting: This operation is done by means of hot chisels and consists of removing extra, metal from the
job before finishing it.

(iv)

Bending: Bending of bars, flats and other such material is often done by a blacksmith. For making a
bend, first the portion at the bend location is heated and jumped (upset) on the outward surface. This
provides extra material so that after bending, the cross-section at the bend does not reduce due to
elongation.

(v)

Punching and drifting: Punching means an operation in which a punch is forced through the work piece
to produce a rough hole.The job is heated, kept on the anvil and a punch of suitable size is forced to
about half the depth of the job by hammering. The job is then turned upside down and punch is forced
in from the otherside, this time through and through. Punching is usually followed by drifting i.e,
forcing a drift in the punched hole through and through. This produces at better hole as regards its size
and finish. \

(vi)

Setting down and finishing: Setting down is the operation by which the rounding of a corner is
removed to make it a square. It is done with the help of a set hammer. Finishing is the operation where
the uneven surface of the forging is smoothened out with the use of a flatter or set hammer and round
stems are finished to size with the use of swages after the job has been roughly brought to desired
shape and size.

(vii)

Forge welding: Sometimes, it may become necessary to join two pieces of metal. Forge welding of
steel is quite common and consists of heating the two ends to be joined to white heat (1050C
1150C). Then the two ends of steel are brought together having previously been given a slight convex
shape to the surfaces under joining. The surfaces are cleaned of scale. They are then hammered

together using borax as flux. The hammering is started from centre of the convex surface and it
progresses to the ends. This results in the slag being squeezed out of the joint.

12.B. Explain the principle of rolling process stating the advantages and disadvantages.
The process of plastically deforming metal by passing it between rolls is known as Rolling'. In
this process the work is subjected to high compressive stresses from the squeezing action of rolls
and to surface shear stresses as a result of the friction between the rolls and the metal. Also, the
frictional forces help for drawing the metal into the rolls.

PRINCIPLE OF ROLLING :
Rolling basically consists of passing the metal piece through two rolls rotating in
opposite directions. The space between the rolls is adjusted to the desired
thickness of the rolled section.
The rolls are in contact with passing metal piece over a sufficient distance
represented by the arc AB in the diagram.
The angle AOB is called Angle of Contact or the Maximum angle of Bite.
The friction between metal piece and rolls provide sufficient grip for the rolls to
move the metal piece through the rolls.
The reduction in thickness increases with coefficient of friction.
The pressure exerted by over the metal by the rolls varies as represented by the
pressure distribution curve in the diagram.
It will be minimum at both the extremities and will be maximum at a point
somewhere in the curve.
The line representing the maximum pressure is called Neutral or No Slip Line
and the point C is known as No Slip Point or the Point of Maximum Pressure. As
the Arc of Contact increases, this point tends to move towards the exit B. Also
when this arc of contact becomes so big that the maximum angle of bite AOB

becomes more than two times the angle of friction between the rolls and the work
and hence point C coincides with B and then rolls cannot draw the work through
them.
At the point C the surface of metal and the roll move at the same speed. Before
this point metal moves slower than the rolls. After crossing the rolls metal move
at a faster rate.
Advantages
Hot rolling brings homogeneity in rolled components.
Grain refinement gives optimum mechanical properties to the alloy.
Time taken to produce the component is less compared to cold rolling.
Disadvantages
Surface oxidation takes place.
Chance of scale inclusion exists.
Process is more expensive.
More care is needed to handle the hot part.
13.A. Briefly state the working of Electro-hydraulic forming with required sketches.
Electro-hydraulic Forming or Spark Forming

Make use of the shock waves and pressure produced due to the conversion
of electrical energy to mechanical energy in a liquid medium for the
forming operation.
Principle : Discharge of an electric spark in the liquid medium produces
shock waves which can be used for metal forming.
Unit is immersed in water.
During operation high voltage is supplied across two electrodes.
Spark created produces high pressure waves form the metal placed in the
dies.
Energy produced is less than that of explosive forming.
Voltages of 10000 to 30000 Volts are generally used.
Process can be used for blanking, piercing, forging etc.
Running cost is less.

 Initial cost is high.

Two methods are used for the conversion of electrical energy to mechanical
energy.
1. Capacitor Discharge through a gap.
2. Capacitor Discharge through a wire.
Advantages :
Low capital investment.
Large amount of energy can be directed.
Reproducibility is another advantage.
Disadvantages :
Initial cost is more.
Applications :
Aerospace components.
13.B. How the Electromagnetic Forming carried out. Explain with Sketch.
Electromagnetic Forming (Magnetic Pulse Forming or MPF) :

Consist of an capacitor, a switch, a coil and a power supply that provides the
energy to charge capacitor.
The current through the coil produces a magnetic field of high intensity
between the coil and the workpiece.
High magnetic field produced between the coil forms the metal piece.
Forming depends up on the design of the coil.
The efficiency of Magnetic pulse depends up on the resistivity of the metal
being formed.
Advantages :
No lubricants are required.
Process is fast.
14. A.ii) Draw neatly the horizontal milling machine stating the components. Also explain its working.
HORIZONTAL MILLING MACHINE

The most common type of milling machine is the horizontal knee type; so called, because of the overhanging
knee which can slide up and down the front of the machine and which carries the cross slide and the table. A
diagram of the horizontal milling machine is given in Fig. 4.9. Horizontal milling machines may be either plain or
universal type. The main difference between the two is that the table of the universal type is mounted on a turn table
and may be swivelled in a horizontal plane. This feature permits the cutting of helix. In addition, the standard
accessories provided on the universal machine include a dividing head for indexing. There are some other minor
refinements, which make the universal horizontal machine very useful for tool room work. The plain version of the
horizontal machine is much more robust and more suitable for production work. In the diagram, the arbor on which
peripheral cutters are mounted is not shown. It is fitted in the spindle nose C and extends a little beyond arbor
supporting bracket B. Even end mills, face milling cutters and drills etc. can be used with this machine. In such a
situation, arbor is removed and the taper shank of these cutters is fitted into the hollow spindle C. With such an
arrangement the vertical faces of the workpiece may be milled without any difficulty. The table of the horizontal
milling machine can be given either hand feed or autofeed. It is also capable of being traversed at high speed.

14. B. i) Explain the Working principle of planer with a neat sketch. (10)

14.B. ii) Distinguish between shaper and planer. (6)

15.A.. Explain with neat sketch the working of centre lathe stating the components. (16)
15. B..i) Detail the nomenclature of the single point cutting tool.