METAL CASTING AND JOINING PROCESSES

UNIT – I METAL CASTING PROCESSES
1. DIFFERENT TYPES OF PATTERN:
Single Piece Pattern: Match Plate Pattern:
Split Pattern:
Cope and Drag Pattern:

Sweep Pattern:
Gated Pattern Skeleton Pattern
Loose Piece Pattern:

2. DIFFERENT TYPES OF ALLOWANCES:
Drift or Taper Allowance:
Distortion or Camber Allowance:
Machining Allowance:

Figure (a) Core held in place in the mold cavity by chaplets, (b) possible
chaplet design, (c) casting with internal cavity.
SQUEEZING MACHINES

JOLT MACHINE
JOLT-SQUEEZE MACHINE

SAND SLINGERS
Direct Arc Electric Furnace

Indirect Arc Electric Furnace
Induction Furnace

CRUCIBLE FURNACES
(a) lift-out crucible, (b) stationary pot, from which molten metal must be ladled,
and (c) tilting-pot furnace.
Shell Molding Process

Investment casting process
STEP 1: Pattern creation
STEP 2: Mold creation
STEP 3: Pouring
STEP 4: Cooling & Casting removal

Ceramic Mold casting Process
The Basic Permanent Mold Process (OR) GRAVITY DIE CASTING

Hot-Chamber Die Casting
Cold-Chamber Die Casting Machine

True Centrifugal Casting
Semicentrifugal Casting

Centrifuge Casting
Defects in casting

Stir casting
BALANCED CORE AND HANGING CORE
HORIZONTAL CORE AND VERTICAL CORE

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(a) Neutral flame (b) Oxidising flame
(c) Carburising flame
OXY ACETYLENE GAS WELDING
UNIT-2 METAL JOINING PROCESSES
OXY ACETYLENE GAS WELDING
MANUAL METAL ARC WELDING
METAL INERT GAS WELDING

TUNGSTEN INERT GAS WELDING
SUBMERGED ARC WELDING
ELECTRO SLAG WELDING
PLASMA ARC WELDING

RESISTANCE SPOT WELDING
RESISTANCE PROJECTION WELDING
RESISTANCE SEAM WELDING
RESISTANCE BUTT WELDING

RESISTANCE PRECUSSION WELDING
ELECTRON BEAM WELDING
THERMIT WELDING
Thermit welding:(1)Thermit ignited;(2) crucible tapped,superheated metal
flows into mold; (3) metal solidifies to produce weld joint.
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Friction welding (FRW):(1) rotating part, no contact;(2) parts brought into
contact to generate friction heat;(3) rotation stopped and axial pressure
applied;and (4) weld created.
FRICTION WELDING

FRICTION WELDING
FRICTION STIR WELDING
BRAZING
SOLDERING

Welding Defects Cont.,
 Cracks cont.,
 Incomplete Fusion
A weld bead in which fusion has not occurred throughout entire
cross section of joint
 Several forms of incomplete fusion are shown below
 Miscellaneous defects
 (a) Desired profile for single V-groove weld joint, (b) undercut -
portion of base metal melted away, (c) underfill - depression in
weld below adjacent base metal surface, and (d) overlap - weld
metal spills beyond joint onto part surface but no fusion occurs

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(a) open-die forging
1Manufacturing Technology I
Three types of forging
UNIT-3 METAL FORMINGPROCESS
(b) impression-die forging
(c
(c) Flashless or Closed forging
FORMING LIMIT DIAGRAM

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Forging Hammers (Drop
Hammers)
Drop forging hammer, fed by conveyor and heating units at the right of
the scene
(photo courtesy of Chambersburg Engineering Company)
5Manufacturing Technology I Manufacturing Technology I 6
BOARD HAMMER
BELT AND CHAIN TYPE HAMMER
Manufacturing Technology I 7
SPRING HAMMER

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PNEUMATIC HAMMER
Manufacturing Technology I 9 Manufacturing Technology I 10
STEAM HAMMER
Forging Presses - Mechanical Presses
• Mechanical presses transform the rotational
force of a motor into a translational force
vector. Therefore the energy in a mechanical
press comes from the motor. Mechanical
presses are generally faster than hydraulic or
screw presses.
1. Crank Presses
2. Knuckle Joint Presses
3. EccentricPresses
4. Rack and Pinion Presses
5. ScrewPresses
Mechanical Forging Presses – Crank
Presses

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MechanicalForging Presses– Knuckle Joint Presses
• The knuckle joint press translates the energy of a motor
through a powerful linkage design, and is capable of
delivering a tremendous amount of force. The drive shaft
crank rotates completely. The links are well grounded to
support such pressure.
Mechanical Forging Presses – Eccentric Presses
Mechanical Forging Presses – Rack and Pinion Presses
Mechanical Forging Presses – Screw
Presses

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Forging Presses - Hydraulic Presses
• Hydraulic presses derive the energy they deliver through
hydraulic pressure. Fluid pressure, in a particular chamber,
can be increased or decreased by the use of pumps, and
valves. Sometimes devices and systems may be used to
increase the capacity of the pumps in more powerful presses.
FORGING OPERATIONS
UPSETTING

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SWAGING
Direct extrusion
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EXTRUSION
Indirect extrusion to produce
(a) a solid cross-section and (b) a hollow cross-section
INDIRECT EXTRUSION

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TUBE EXTRUSION
HYDROSTATICEXTRUSION
HOT EXTRUSION Impact Extrusion

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Drawing of bar, rod, or wire
Continuous drawing of wire
Wire Drawing

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Draw die for drawing of round rod or wire
Tube Drawing cont.,
Without Mandrel
(Tube Sinking)
With Fixed Mandrel With Floating Mandrel
• Deformation process in which work thickness is reduced
by compressive forces exerted by two opposing rolls
The rolling process (specifically, flat rolling)
ROLLING
Rolling Mills OR FLAT STRIP ROLLING
• Rollingmill consists basically of rolls, bearings,
housing for containing these parts and a drive for
applyingpower to the rolls and control their
speed.
• Equipmentis massive and expensive
• Rollingmill configurations:
– Two-high– two opposing large diameter rolls
– Three-high– work passes through both directions
– Four-high – backing rolls support smaller work rolls
– Cluster mill – multiple backing rolls on smaller rolls
– Tandemrolling mill – sequenceof two-high mills

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Various configurations of rolling mills:
(a) 2-high rolling mill
(b) 3-high rolling mill
(c) four-high rolling mill
Cluster Mill
Multiple backing rolls allow even smaller roll diameters
Various configurations of rolling mills: (d) cluster mill

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Tandem Rolling Mill
A series of rolling stands in sequence
(e) tandem rolling mill
Thread Rolling or Shape Rolling
• Bulk deformation process used to form threads on
cylindrical parts by rolling them between two dies
• Most important commercial process for mass producing
bolts and screws
• Performed by cold working in thread rolling machines
Thread rolling with flat dies:
(1) start of cycle, and (2) end of cycle
Ring rolling used to reduce the wall thickness and increase the diameter
of a ring:
(1) start, and (2) completion of process
Ring Rolling
DefectsIn MetalRolling
44
Manufacturing Technology ISource: http://thelibraryofmanufacturing.com/metal_rolling.html

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UNIT-4 SHEET METAL PROCESSES
VARIOUS SHEARING OPERATIONS Sheet Metal - cupping test
2
Manufacturing Technology I
3
Forcedistribution during bending
Elastic core during bending
4
Spring back

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5
Compensation of spring back
6
Bending operationsinvolve the processes of
V-bendingand edge bending
V -
bending
Edge -
bending
7
Bending operationsinvolve the processes of Rotarybending
Rotarybending
8
Air bending and Offset bending
Air bending Offset bending

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9
Channelbending and U bending
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Bending operationsinvolve the processes of Roll Bending
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Tube Bending
12
Tube Bendingcont.,

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13
Drawing
• Deep drawing is a sheet-metal operation to makehollow-shaped
parts from a sheet blank
14
DrawingProcess
Drawingcont.,
15
• RedrawingSheetMetal cont.,
16
• RedrawingSheetMetal
• Redrawing is the subsequent deep drawing of a work that has
alreadyundergone a deep drawing process.
• By using morethan one operationa greater magnitude of deep
drawing can be accomplished.

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17
• ReverseRedrawingSheetMetal
• Reverse redrawing, or reverse drawing is sometimesused to
redraw parts. In reverse redrawing the intermediate part is
flipped over before being placed on the die for the next
operation.
Drawingcont.,
18
• ForcesIn Deep Drawing
19
Ironing
• Ironing is mostly used to achieve a uniform wall thickness in deep
drawings.
• Variationin wall thickness often exists in such parts as discussed
in the previous section.
• Ironing can be incorporatedinto a deep drawing process or can
be performed separately.
Sheetmetal cont.,
20
Other sheet-metal forming operations
• Rubber forming / Guerin process
• Hydroforming
• Stretchforming
– Shear Spinning
– Tube Spinning

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Sheetmetal cont.,
21
The Guerin process cont.,
Advantages: smallcost of tooling
Limitations: for relatively shallow shapes
Area of application: small-quantity production
22
• Hydroforming
• It is similar to Guerin process but instead of rubber pad a rubber
diaphragm filled with fluid is used
23
• Stretchforming
• In stretch formingthe sheet metalis stretched and bent to
achievethe desired shape
24
• Spinning
• Spinning is a metal formingprocess in which an axially symmetric
part is gradually shaped over a mandrel by means of a rounded
toolor roller

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25
• Shear Spinning
• Shear spinning is a process related to conventionalspinning, and
is also known as flow turning and spin forging.
26
• Tube Spinning
• Tube spinning is performed on cylindrical parts. Tube spinning is
similar to shear spinning in that metalflow occurswithin the
work.
27
High-energy-rate Forming (HERF)
• Explosiveforming
• It involves the use of an explosive chargeplaced in water to form
sheet into the die cavity.
28
• Electrohydraulic forming
• This is a HREF process in which a shock wave to deform the work
into a die cavity is generated by the discharge of electrical energy
between two electrodes submerged in water.
• Similar to explosive forming, but applied only to small part sizes.

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29
• Electromagnetic forming (OR) magnetic pulse
forming
• The sheet metal is deformed by the mechanical
force of an electromagnetic field induced in the
workpieceby a coil
Peen Forming
30
Peen Forming
31
SUPERPLASTICFORMING PROCESS

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UNIT-5
PLASTIC PROCESSING
METHODS
INJECTION MOULDING-SCREW TYPE
INJECTION MOULDING-PLUNGERTYPE
4
VacuumThermoforming
• The process involves
shaping a preheated
thermoplastic sheet by
means of vacuum
produced in the mold
cavityspace.
• The atmospheric pressure
forces the soft sheet to
deform in conformity with
the cavity shape.
• When the plastic comes
into the contact with the
mold surface it cools down
and hardens.

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5
PressureThermoforming
shaping a preheated
means of air pressure.
• The air pressure forces
the soft sheet to deform
in conformity with the
cavityshape.
• When the plastic comes
into the contact with the
mold surface it cools
down and hardens.
6
MechanicalThermoforming
shaping a preheated
means of a direct
mechanicalforce.
• A core plug (positive
mold) forces the soft
sheet to fill the space
between the plug and the
negative mold.
• The process provides
precise dimensional
tolerance and surface
detailing.
Film Blowing
Rotational molding

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MoldingCont.,
Calendaring
• Molten plastic forced between two counter-
rotating rolls to produce very thin sheets e.g.
polyethylene sheets
ExtrusionBlow Molding

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Bonding of thermoplastics
Methods of Bonding
• Chemical Bonding
– SolventBonding
– Adhesive Bonding
• Thermal welding
– Friction welding Technique
• Ultrasonic welding
• Spin welding
• Radio frequency welding
• Electromagneticor Induction welding
• Hot plate
• Laser welding
ULTRASONICWELDING
15Manufacturing Technology I 16Manufacturing Technology I
• Electromagnetic or Induction welding

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Hot plate welding Cont.,
• When this condition is achieved the hot plate is removed,
and the parts are pressed together and held until the weld
joint cools and re-solidifies to create a permanent bond.
• The most common form of this welding is butt heat
fusion welding which welds two circular tubes end to end.
LASER WELDING

METAL CASTING AND JOINING PROCESSES

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METAL CASTING AND JOINING PROCESSES