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UEET 601 Modern Manufacturing Introduction to manufacturing processes Metal Casting 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.

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ueet 601

UEET 601

Modern Manufacturing

Introduction to manufacturing processes

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
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
casting processes
Expendable Mold

Sand casting

Shell molding

Lost foam process

Lost wax (investment casting)

Permanent Mold

Die casting

Centrifugal casting

Casting Processes
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
  • 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



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
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.
  • 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
types of forging processes
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
types of forging processes16
Types of forging processes
  • Impression Die and Closed Die Forgings
    • Example – alloy ream
    • Coining
  • 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

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

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.
  • Top of Page
  • Metals Handbook Rev. ed., by Davis, J.R. (ed.)Manufacturing Processes for Engineering Materials 3rd ed., by Kalpakjian, S.Engineering Materials: Properties and Selection 6th ed., by Budinski, K.G., Budinski, M.K. (ed.)
  • .

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

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

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


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

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

  • 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
  • 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
  • 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
  • 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
Other Bending Processes:
  • Press brake bending - used to form for example seam joints
  • Roll bending
  • Beading
  • Flanging, dimpling, hemming
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
  • Variety of operations e.g. punching, blanking, embosing, coining
  • Roll bending
  • Beading
  • Flanging
  • Roll forming
  • Tube bending and forming
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

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

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.
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

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

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

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

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.

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.
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
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
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
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
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.

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 Virtual

subtractive processes
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
additive processes
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
types of rr processes
Types of RR processes
  • Fused Deposition Modeling (FDM)
  • Stereolithography
  • Selective Laser Sintering
  • Solid-Base Curing (Solid Ground Curing)
  • Laminated Object Manufacturing (LOM)
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
virtual prototyping
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.
applications of rapid prototyping
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.
  • 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.
tool materials
Tool Materials
  • Carbon and Medium Alloy Steels
  • High Speed Steel
  • Carbides
  • Ceramics (cermets)
  • Diamonds
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
  • 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
common types
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
common types73
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
  • 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
fusion welding processes
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.
types of fusion welding processes
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.
types of fusion welding processes79
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
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
metal cutting processes
Metal cutting processes
  • Oxy-Fuel Cutting
  • Arc – cutting
  • Plasma cutting
brazing and soldering
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

methods of brazing
Methods of brazing
  • Torch
  • furnace
  • induction
  • resistance
  • deep brazing
applications of brazing
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
  • 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)
types of soldering procedures
Types of Soldering Procedures
  • Soldering Irons
  • Torch soldering
  • Dip soldering
  • Wave soldering
  • Oven soldering
  • Resistance soldering
  • Induction soldering
  • Infrared soldering
applications of soldering
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