UEET 601

1
UEET 601

• Modern Manufacturing
• Introduction to manufacturing processes

2

• Metal Casting

3

• Casting Process
• Involves flow of molten metal into mold cavity -
  cavity has a shape of the finished part machined
  into it. Melt is allowed to cool and solidify.
  Final product removed from mold.
• Important considerations
• flow of melt into cavity
• solidification and cooling of metal in the mold
• influence of the type of mould material
• Typical applications
• Engine blocks/components, pump housings, brake
  rotors and drums, complex shapes

4

• Flow of Melt in the Mold
• Melt is poured into mold cavity through a POURING
  CUP
• Melt flows through the GATING SYSTEM which
  consists of
• Sprue- vertical channel through which melt flows
  downward
• Runners - channels that carry melt from sprue
  into cavity
• Gate - part of the runner through which melt
  enters cavity
• Risers - reservoirs that supply melt and prevent
  shrinkage during solidification

5
Casting Processes

• Expendable Mold
• Sand casting
• Shell molding
• Lost foam process
• Lost wax (investment casting)

• Permanent Mold
• Die casting
• Centrifugal casting

6
Forming and Shaping Processes
7

• Forming Processes - involve processes that
  deform the initial material plastically into a
  final material - sometimes through various stages
• In both processes, product can be discrete (e.g.
  a connecting rod) or continuous (e.g. sheet
  metal)
• Workability - refers to bulk deformation
  processes. Forces applied are predominantly
  compressive (e.g. forging). To be studied
  Rolling and Forging
• Formability - refers to sheet forming processes
  in which forces applied are predominantly tensile
  (e.g. tube drawing). To be studied Extrusion
  and Sheet Metal Forming

8
Rolling Processes
9

• Introduction
• Process that reduces thickness or changes the
  cross section of a long work-piece by application
  of compressive forces through a set of rolls.
• Can be done when the workpiece is cold - COLD
  ROLLING or when hot (above recrystallization
  temperature) - HOT ROLLING

Rolls
Work-piece
10

• Flat Rolling
• A sheet or block or strip stock is introduced
  between rollers and then compressed and squeezed.
  Thickness is reduced. The amount of strain
  (deformation) introduced determines the hardness,
  strength and other material properties of the
  finished product.
• Used to produce sheet metals predominantly

11

• Other Rolling Processes
• Shape or Profile Rolling - Straight, long
  structural parts produced with various cross
  sectional shapes. Profile roles or roll
  combinations used to achieve this
• Thread Rolling - used for making external
  threads. A die with the thread profile, is
  pressed on to a rotating work-piece.

12
Forging Processes
13

• Introduction
• Forging - metal is heated and is shaped by
  plastic deformation by suitably applying
  compressive force hammer blows using a power
  hammer or a press.
• Forgings yield parts that have high strength to
  weight ratio - thus are often used in the design
  of aircraft frame members.
• A Forged metal can result in the following -
• Decrease in height, increase in section - open
  die forging
• Increase length, decrease cross-section, called
  drawing out.
• Decrease length, increase in cross-section on a
  portion of the length - upsetting
• Change length, change cross-section, by squeezing
  in closed impression dies - closed die forging.
  This results in favorable grain flow for strong
  parts

14
(No Transcript)
15
Types of forging processes

• Open Die Forgings / Hand Forgings
• E.g. traditional blacksmith
• Heading - Upsetting process that increases
  cross-section by compressing a portion of the
  length (hot or cold)
• this is used in making heads on bolts and
  fasteners, valves and other similar parts

16
Types of forging processes

• Impression Die and Closed Die Forgings
• Example alloy ream
• Coining

17
Extrusion and Drawing Processes
18

• Extrusion
• Process by which long straight metal parts can be
  produced.
• Cross-sections that can be produced vary from
  solid round, rectangular, to L shapes, T shapes,
  tubes and many other different types
• Done by squeezing metal in a closed cavity
  through a die using either a mechanical or
  hydraulic press.
• Extrusion produces compressive and shear forces
  in the stock.
• No tension is produced, which makes high
  deformation possible without tearing the metal.
• Can be done Hot or cold

19

• Direct or Forward - round billet forced through
  die opening
• Cold Extrusion Cold extrusion is the process
  done at room temperature or slightly elevated
  temperatures. This process can be used for most
  materials-subject to designing robust enough
  tooling that can withstand the stresses created
  by extrusion. Examples of the metals that can be
  extruded are lead, tin, aluminum alloys, copper,
  titanium, molybdenum, vanadium, steel. Examples
  of parts that are cold extruded are collapsible
  tubes, aluminum cans, cylinders, gear blanks. The
  advantages of cold extrusion are
• No oxidation takes place.
• Good mechanical properties due to severe cold
  working as long as the temperatures created are
  below the re-crystallization temperature.
• Good surface finish with the use of proper
  lubricants.
• Hot Extrusion Hot extrusion is done at fairly
  high temperatures, approximately 50 to 75 of
  the melting point of the metal. The pressures can
  range from 35-700 MPa (5076 - 101,525 psi). Due
  to the high temperatures and pressures and its
  detrimental effect on the die life as well as
  other components, good lubrication is necessary.
  Oil and graphite work at lower temperatures,
  whereas at higher temperatures glass powder is
  used.
• Typical parts produced by extrusions are trim
  parts used in automotive and construction
  applications, window frame members, railings,
  aircraft structural parts.

• most common of the extrusion processes in
  industry
• the billet is upsetted in the container, so that
  it assumes the bore diameter of the container
• it is then pressed by the stem through the die
• there is relative motion between block and
  container - FRICTION. Use lubricants

20

• Indirect Extrusion - Reverse or backward
  extrusion- Die moves towards billet

• Billet also upsetted first in the container
• a dummy block used to lock the container from one
  side
• a hollow stem pushes die into the billet OR dummy
  block and container may push billet through die
  and hollow container (smaller friction)

21

• Hydrostatic Extrusion - billet is smaller,
  chamber filled with a fluid -HYDROSTATIC FLUID

• container space is sealed
• pressure is transmitted by ram (or stem)
• during extrusion the does not touch the billet
• less friction between billet and container

22

• Impact Extrusion - Blank or slug is extruded
  backward by impact force to form a thin walled
  tube

• used for hollow shapes
• usually performed on a high-speed mechanical
  press - punch descends at a high speed and
  strikes the blank, extruding it upwards
• performed cold considerable heating results from
  the high-speed deformation
• restricted to softer metals such as lead, tin,
  aluminum and copper
• used to produce medicine and toothpaste tubes

23

• Drawing
• X section of material reduced by pulling through
  die
• Similar to extrusion except material is under
  TENSILE force since it is pulled through the die
• Various types of sections - round, square,
  profiles
• Tube Drawing - Utilizes a special tool called a
  MANDREL is inserted in a tube hollow section to
  draw a seamless tube
• Mandrel and die reduce both the tube's outside
  diameter and its wall thickness. The mandrel also
  makes the tube's inside surface smoother

24
Sheet Metal Forming
25

• Introduction
• Involves methods in which sheet metal is cut into
  required dimensions and shape and/or forming by
  stamping, drawing, or pressing to the final shape
• A special class of metal forming where the
  thickness of the piece of material is small
  compared to the other dimensions
• Cutting into shape involve shear forces
• Forming Processes involve tensile stresses

26

• Shearing
• Process for cutting sheet metal to size out of a
  larger stock
• Shears are used as the preliminary step in
  preparing stock for stamping processes, or
  smaller blanks for CNC presses.
• Sheet is cut by subjecting it to a shear stress

27
(No Transcript)
28

• Bending
• Bending is a process by which metal can be
  deformed by plastically deforming the material
  and changing its shape
• Flexible different shapes can be produced
• Standard die sets can be used to produce a wide
  variety of shapes

29
(No Transcript)
30

• Other Bending Processes
• Press brake bending - used to form for example
  seam joints
• Roll bending
• Beading
• Flanging, dimpling, hemming

31

• Deep Drawing
• In deep drawing, a blank of sheet metal is
  restrained at the edges by BLANKHOLDER, and the
  middle section is forced by a punch into a die to
  stretch the metal into a cup shaped drawn part.
  This drawn part can be circular, rectangular or
  otherwise

32

• Stamping
• Variety of operations e.g. punching, blanking,
  embosing, coining

33

• Others
• Roll bending
• Beading
• Flanging
• Roll forming
• Tube bending and forming

34
Processing of Powder Metals, Ceramics and Glass
35

• Powder Metallurgy (P/M)
• Process by which metal parts are made by
  compacting fine metal powders in a die and
  heating without melting (SINTERING)
• Produces mostly NET shapes
• Most commonly used metal powders are iron,
  copper, aluminum, tin, nickel, titanium, and
  refractory alloys
• Major attraction of P/M is the ability to
  fabricate high quality parts with complex shapes
  to close tolerances in an economical manner
  highly porous parts, precision parts of high
  performance as well as composite materials can be
  produced by P/M
• Process consists of
• 1-Powder production 2-Blending 3-Compaction
• 4-Sintering 5-Finishing operations

36

• Applications of P/M
• Tungsten lamp filaments, dental fillings, oil
  less bearings, automotive transmission gears,
  electrical contacts, orthopedic implants, high
  temperature filters, aircraft brake pads and
  landing gear, impellers in APUs

37

• Processing of Ceramics
• Generally procedure involves
• Crushing/grinding (Comminution) material into
  very fine particles
• Mixing with additives to impart certain
  characteristics
• Shaping
• Drying
• Firing

38

• Forming and Shaping of Glass
• Process involves -
• Melting
• Shaping in Molds or other devices
• Strength improvements obtained by chemical and
  thermal treatments or by laminating with a thin
  plastic (Auto glass)
• Types of Products
• - sheet or plate
• - rods and tubes
• - discrete products (e.g. bottles)
• - glass fibers (for composite reinforcement)

39

• Methods of Processing -
• a) Flat sheet plate
• Drawing - molten glass drawn through a pair of
  rolls
• Rolling - molten glass squeezed between rolls
• Float method - molten glass floats into a bath of
  molten tin under controlled atmosphere then
  drawn out by a set of rolls. Smooth surface
  finish
• b) Tubes and Rods -
• Tube -Molten glass wrapped around a mandrel
  (hollow or conical) and drawn by a set of rolls
  air is blown through the mandrel to prevent tube
  wall from collapsing
• Rod - Similar except no mandrel.

40

• c) Glass Fibers -
• Long fibers - drawing through multiple orifices
  in heated platinum plates at high speeds
• Short fibers - molten glass fed into rotating
  head - CENTRIFUGAL SPRAYING
• d) Discrete parts - Several methods.
• Blowing - used to manufacture thin walled
  products such as bottles or flasks
• Pressing - Molten glass pressed into shape in a
  mold
• Centrifugal casting or spinning -centrifugal
  force forces molten glass onto rotating mold
  walls and cools into shape

41
Processing of Polymers and Composite Materials
42
Polymers

• 1. Casting molten polymer allowed to solidify
  inside a mold cavity to acquire the desired
  shape. For thermosets, additional curing may be
  necessary. Examples thermoplastic sheets
  plates thermoset lenses, gears
• 2. Blow Molding- used to make thermoplastic
  bottles and hollow sections. Starting material is
  a a round heated solid-bottom hollow tube
  preform. Preform inserted into two die halves and
  air is blown inside to complete the process

43

• Blow molding process

44

• 3. Compression Molding thermoset granules are
  compressed in a heated mold to shape required.
  Examples plugs, pot handles, dishware

45

• 4. Transfer Molding similar to compression
  molding except thermosetting charge is forced
  into a heated mold cavity using a ram or plunger.
  Examples electrical switchgear, structural parts
• 5. Cold Molding charge is pressed into shape
  while cold then cured in an oven. Economical but
  usually poor surface finish
• 6. Injection Molding Most widely used process.
  Suitable for high production of thermoplastics.
  Charge fed from a hopper is heated in a barrel
  and forced under high pressure into a mold
  cavity. Several types. Variety of parts can be
  made.

46

• Example of an injection molding system

47

• 7. Extrusion Similar to injection molding
  except long uniform sections are produced e.g.
  pipes, rods, profiles

48

• 8. Thermoforming Sheet material heated to
  working temperature then formed into desired
  shape by vacuum suction or pressure. Suitable for
  large items such as bath tubs

49

• 9. Rotational Molding used to form hollow
  seamless products such as bins. Molten charge is
  rotated in a mold in two perpendicular axes
  simultaneously, or rotated while tilting.
• 10. Foam Molding Foaming agent is combined with
  the charge to release gas, or air is blown into
  mixture while forming. Used to make foams. Amount
  of gas determines the density

50

• 11. Others-
• -Calendaring molten plastic forced between two
  counter-rotating rolls to produce very thin
  sheets e.g. polyethylene sheets
• -Spinning modified form of extrusion in which
  very thin fibers or yarns are produced
• -Machining material removal process such as
  drilling, turning, thread cutting. E.g. nylon
  fasteners. In general thermoplastics have poor
  machinability.

51

• Composite Materials
• Processing requires care and several methods
• Safety and environmental concern over the dust
  generated from particles
• For good bonding with matrix, fibers are surface
  treated by impregnation - SIZING
• When impregnation is carried out as a separate
  step, several types of partially cured sheets can
  be produced
• Prepreg - Reinforcing material aligned and
  impregnated with resin prior to the molding
  process and cured by the application of heat.
  Example F14 horizontal stabilizer.

52

• Sheet Molding Compound (SMC) - continuous strands
  of fibers cut into short strands then deposited
  in random directions over layer of polymer
  resin., a second layer of resin deposited on top
  and material pressed between rolls. Allowed to
  mature under controlled temperature and humidity
• Bulk molding compounds (BMC) - material is bulky
  or shaped like a billet, but processing similar
  to SMC
• Thick Molding compound (TMC) - combines
  characteristics of BMC and SMC.
• Methods of Processing include Molding, Filament
  Winding, Pultrusion, Pulforming

53

• Molding - Several types of molding processes
• Compression molding - composite material
  compressed under heat in a mold
• Vacuum-bag molding - prepregs laid in a mold to
  form desired shape, then covered with plastic
  bag. Pressure to form is obtained by applying a
  vacuum to the bag
• Contact molding - Uses a single mold to make
  shapes like boats. Lay-up of prepreg may be
  manual using rollers and brushes - HAND LAY-UP or
  by SPRAY LAY-UP
• Resin Transfer Molding - Resin mix forced into
  mold cavity that is filled with reinforcement,
  through a pump
• Transfer/injection Molding- combines transfer
  and injection molding in an automated process

54

• Filament Winding- involves winding a
  resin-saturated strand of reinforcing filament
  around a rotating mandrel until desired thickness
  is obtained. Used for axisymmetric parts - pipes,
  storage tanks asymetric parts - aircraft
  fuselage, propeller blades

55

• Pultrusion- fibers are brought together over
  rollers, dipped in resin and drawn through a
  heated die. A continuous cross section composite
  part emerges on the other side. Very applicable
  for long shapes with uniform sections such as
  rods, or even pipes

56

• Pulforming- used to make continuos products not
  necessarily having uniform cross section. After
  pulling through a polymer bath, composite is
  cured inside to heated die halves into required
  shape.

57
Rapid Prototyping
58
Prototype is a new examinable product, usually
still under development required for tests and
evaluation Rapid Prototyping is a new technology
which speeds up the process of product
development Usually, new physical model can be
built from a CAD file in a matter of hours There
are three basic types Subtractive Additive Vir
tual
59
Subtractive Processes

• Uses computer based technologies in design,
  drafting and manufacturing to speed up process of
  the production of prototype
• Requires software that can translate CAD data
  into format usable for manufacturing and CNC
  software
• Used only when shape verification of prototype is
  needed - a soft material like wax is used to
  manufacture the prototype by any conventional or
  non-conventional method

60
Additive Processes

• Parts are built in layers (or slices)
• Five basic steps-
• Create a CAD model of the design
• Convert the CAD model to STL (stereolithography)
  format
• Slice the CAD model to STL format
• Model constructed one layer on top of another
• Cleaning and finishing operations
• There are several types

61
Types of RR processes

• Fused Deposition Modeling (FDM)
• Stereolithography
• Selective Laser Sintering
• Solid-Base Curing (Solid Ground Curing)
• Laminated Object Manufacturing (LOM)

62

• Limited design restrictions -- can produce any
  thing that can be designed on a CAD application
• Automatic scaling -- accurately scales part to
  fit inside machine production space
• Disadvantages
• Limited material -- works with only a few
  plastics and ceramics
• Limited size
• High Cost of actual machine

63
Virtual Prototyping

• Uses advanced software to render CAD design
  features for simulation and analysis (no
  prototype built)
• Examples - Boeing 777 production - there was no
  prototype built.

64
Applications of Rapid Prototyping

• Production of finished items - only viable for
  polymeric materials
• Shape verification of models
• Simulation and analysis of products during design
  stage
• Rapid tooling - RP models used as a pattern to
  create a mold quickly or uses the RP process
  directly to fabricate a tool for a limited volume
  of prototypes.

65
Material Removal Processes
66
Introduction

• Involves shaping of parts by material removal
  process
• Can range from a simple operation such as sawing
  off a riser to complex operations involving
  Computer controlled machines
• Categories-
• Cutting -single point or multi-point tool
• Abrasive processes
• Advanced processes - ECM, EDM, EBM, LBM, e.t.c.

67
Common Types of Metal Cutting Processes

• Turning Milling Drilling

68
Tool Materials

• Carbon and Medium Alloy Steels
• High Speed Steel
• Carbides
• Ceramics (cermets)
• Diamonds

69

• Cutting Fluids
• Essentially a coolant or lubricant or both
• Cutting fluids accomplish the following-
• Reduce friction and wear - improve tool life and
  surface finish
• Reduce forces and hence power for cutting
• Cool work-tool interface, thus reducing thermal
  distortion
• Wash away chips
• Protects machined surface from corroding
• Types of coolants - Oils, emulsions,
  synthetics, vegetable oils

70
Advanced Machining Processes
71
Introduction

• Advanced machining methods - also referred to as
  non-traditional machining methods
• Have been developed to complement traditional
  machining processes (TM) in situations where it
  is not feasible to use TM methods -
• work material too hard or brittle
• workpiece too flexible to hold
• part shape too complex
• surface finish and dimensional requirements too
  rigorous
• temperatures and residual stresses involved
  undesirable

72
Common Types

• Chemical Machining - Selective chemical
  attack/etching on a metallic material surface
  using selected chemical reagents or ETCHANTS
• Photo-Chemical Machining (PCM)- also known as
  Photo Etching - used to produce precision parts
  and decorative items, mainly sheets and foils.
• Laser Beam Machining -source of energy is a laser
  beam

73
Common Types

• Electrochemical machining (ECM) - Reverse of
  electroplating in which metal is selectively
  removed from the anode by electrolytic action of
  a specially shaped cathode tool
• Electric discharge machining (EDM), also called
  electrodischarge or spark-erosion machining -
• EDM works by eroding material in the path of
  electrical discharges that form an arc between a
  shaped electrode tool and the workpiece.
• Workpiece is immersed in a dielectric fluid which
  also acts to flush away debris

74
Welding and Joining Processes
75
Introduction

• Joining processes fall into three different
  categories
• welding
• adhesive bonding
• mechanical fastening
• Welding processes can be divided into three
  categories
• fusion welding
• solid state welding
• non-fusion welding

76
Fusion Welding Processes

• Fusion Welding -
• heat is applied to melt metal locally at joint
• the joint is allowed to solidify and fuse
• source of heat can be an electrical arc or a
  flame
• filler material may be required to fill the gap.

77
Types of fusion welding processes

• 1. Oxyfuel (gas) welding
• Source of heat is a gaseous fuel combined with O2
• Fuels -
• acetylene (oxyacetylene welding - the most
  common)
• others (mostly used for cutting - propane,
  hydrogen, MAPP, propylene, natural gas)
• when mixed together in correct proportions within
  a hand-held torch or blowpipe, a relatively hot
  flame is produced with a temperature of about
  3,200 deg.C.

78
(No Transcript)
79
Types of fusion welding processes

• 2. Arc - Welding Processes
• Heat source is from an electrical arc
• electrode can be consumable (also acts as filler)
  or non-consumable (separate filler is required)
• there are several types of arc welding processes
• shielded metal arc (consumable electrode)
• gas shielded processes TIG (non - consumable),
  MIG (consumable)
• submerged arc welding
• flux-cored arc welding
• Plasma arc welding

80
(No Transcript)
81

• Other Welding Processes
• Solid State welding
• Ultrasonic welding - used for both metallic and
  non-metallic processes especially thin sheets
  used extensively in plastics
• Resistance welding - commonly used in sheet
  metals very popular in automotive body assembly
• Brazing and Soldering
• Other Joining Processes
• Adhesive bonding - a wide variety
• Mechanical fasteners - bolts, rivets, screws, etc

82
Metal cutting processes

• Oxy-Fuel Cutting
• Arc cutting
• Plasma cutting

83
Brazing and Soldering

• Non-fusion joining processes
• Dissimilar materials can be joined
• Brazing is done when two metals, which are not
  melted, are joined with a third metal that melts
  at temperatures above 840 deg F.
• Soldering occurs when two metals, which are not
  melted, are joined by a third metal having a
  melting point below 840 deg. F

84
Methods of brazing

• Torch
• furnace
• induction
• resistance
• deep brazing

85
Applications of brazing

• Automotive
• air conditioner heat exchanger
• heater heat exchanger
• radiator core (engine heat exchanger)
• Fuel rail for injectors
• pollution control stainless tubing
• Aerospace
• jet engine parts
• rocket engines
• Plumbing
• faucets
• larger piping in multistory buildings

86
Soldering

• Occurs when two metals, which are not melted, are
  joined by a third metal having a melting point
  below 840 deg. F
• Biggest advantage minimum warpage and minimal
  disturbance of the heat treatment of the parent
  metal
• Typical fillers
• Tin-lead (most common)
• Tin-zinc
• Lead-silver
• Tin-silver (electronics)
• Tin-bismuth (electronics)

87
Types of Soldering Procedures

• Soldering Irons
• Torch soldering
• Dip soldering
• Wave soldering
• Oven soldering
• Resistance soldering
• Induction soldering
• Infrared soldering

88
Applications of Soldering

• Soldering is used for the following desired
  characteristics
• leakproof joints
• neatness
• low-resistance electrical joint
• sanitation
• Soldered joint is not as strong as a brazed or
  welded joint
• Soldered assemblies must be kept at low operating
  temperatures to prevent the soldered joint from
  failing