UEME 1233 Manufacturing Technology I - Topic 1

• UEME 1233 is a Manufacturing Technology I course taught by Ir. Ts. Dr. Lee Hwang Sheng at [email protected]

Topic 1: Introduction of Manufacturing Technology and Processes

• Manufacturing Engineering and Technology by Kalpakjian and Schmid is a key reference for this topic

Outline

• Introduction of Manufacturing
• Product Design and Concurrent Engineering
• Design for Manufacture, Assembly, Disassembly, and Service
• Sustainable Design and Manufacturing
• Selection of Manufacturing Processes
• Selection of Materials
• Importance of Materials in Manufacturing Technology
• Includes Types of atomic Bond
• Includes Materials Deformation
• Includes Imperfections
• Includes Recovery, Recrystallization, and Grain Growth
• Includes Cold, Warm, and Hot Working
• Includes Heat Treatment

Introduction to Manufacturing

• Raw materials are transformed into finished goods through mass production
• Manufacturing can involve single or multiple components
• Manufacture (1567) is derived from the Latin "manu factus," meaning "made by hand"
• Discrete products are individual items like bolts, nuts, and keys
• Continuous products are cut into individual pieces, such as aluminum foil, wire spools, and plastic tubing

Introduction of Manufacturing

• Manufacturing provides necessary tools for product creation
• Quality products = raw materials + design + worker + process + manufacturing tools
• Lean Manufacturing reduces waste in the entire manufacturing system
• Cellular Manufacturing involves arranging machines layout
• Agile Manufacturing combines materials, processes, tools, and equipment to adapt to changing customer needs and market requirements

Product Design and Concurrent Engineering

• Traditional design involves steps from product need to sales literature, with a timeline varying based on product complexity
• Concurrent engineering integrates market analysis to marketing the product

Design for Manufacture, Assembly, Disassembly, and Service

• Types of production is based on the number of parts produced annually and the rate of production
• Important economic considerations determine appropriate processes and machinery
• Job shops: Have small lot sizes of less than 100, and use general-purpose machines, often with computer controls
• Small-batch production: Quantities range from about 10 to 100, using machines similar to those in job shops
• Batch production: Lot sizes range from 100 to 5000, using more advanced machinery with computer control
• Mass production involves lot sizes generally over 100,000, using dedicated machines and automated equipment

Design for Manufacture (DFM)

• DFM integrates the design process with production methods, materials, process planning, assembly, testing, and quality assurance
• DFM requires understanding the characteristics, capabilities, and limitations of materials, manufacturing processes, machinery, equipment, and tooling
• DFM includes managing variability in machine performance, dimensional accuracy, surface finish, processing time, and effects on product quality
• Establishing quantitative relationships to optimize design for ease of manufacturing and assembly at a minimum product cost is key to DFM
• Design for Assembly (DFA), Design for Manufacture and Assembly (DFMA), and Design for Disassembly (DFD) are key aspects of DFM
• 3-D conceptual designs and solid models help minimize assembly and disassembly times and costs while maintaining product integrity
• Products easy to assemble are usually easy to disassemble

Design for Service

• Designing for service is an important aspect of product design
• Products often require disassembly for service or repair
• Designs should allow easy access to components that need servicing, placing them on the outer layers of the product

Sustainable Design and Manufacturing

• Sustainable design and manufacturing focuses on designing for the environment (DFE)
• Environmentally conscious design and manufacturing (green design) considers all adverse environmental impacts of materials, processes, and products from the earliest stages of design and production
• A key principle of design for recycling is using materials and features that facilitate biological or industrial recycling

Sustainable Design and Manufacturing Cycles

• Biological cycle: Organic materials naturally degrade into soil that sustains life; involves using organic materials and ensuring products function and can be safely disposed
• Industrial cycle: Materials in the product are recycled and reused continuously
• Producing aluminum from scrap reduces costs by about 66%, and reduces energy consumption and pollution by over 90%

Selection of Manufacturing Processes

• Casting processes consist of expendable pattern and mold, expendable mold and permanent pattern, and permanent mold
• Bulk-deformation processes consist of rolling, forging, as well as extrusion and drawing
• Sheet-metal-forming processes consist of shearing, bending and drawing, and forming
• Polymer-processing methods include Thermoplastics, Thermosets, and Rapid prototyping
• Machining and finishing processes consist of machining, advanced machining, and finishing
• Joining processes are fusion welding, other welding, and fastening and bonding

Selection of Materials

• Materials in Car Components include cast iron/aluminum engine blocks, steel/aluminum or reinforced-plastic body, and plastic bumpers/dashboards/seats
• Other materials include the glass windows, plastic taillight lenses, as well as rubber tires
• Metals are split into ferrous and nonferrous
• Amorphous metals are also classified in the metal group
• Plastics are classified as Thermoplastics, Thermosets and Elastomers
• Engineering materials consist of metals, plastics ceramics and others and composites

Selection of Materials

• Behavior and manufacturing properties include structure, mechanical, physical/chemical properties, and property modification
• Structure includes atomic bonds as well as crystalline behavior
• Mechanical properties include strength, ductility, elasticity to name a few
• Physical and chemical properties are density, melting point and specific heat to name a few
• Property modification includes heat treatment, precipitation hardening, annealing, tempering, surface treatment to name a few

Importance of Materials in Manufacturing Technology

• Structure of materials greatly influences their behavior and properties
• Knowledge of structure helps control and predict metal behavior in manufacturing processes
• Predict and evaluate material properties
• Allows selection for specific applications under force, temperature, and environmental conditions

Factors Influencing Material Properties

• Atomic structure
• Composition
• Impurities and vacancies
• Grain size and grain boundary
• Surface condition
• Environment
• Method/process

Types of Atomic Bonds

• Atomic structure of metals is the arrangement of atoms, it controls and predicts metal behavior in manufacturing
• All matter consists of atoms with a nucleus of protons and neutrons, as well as electrons
• Balanced atoms have equal electrons and protons, imbalance causes an ion.
• Excess electrons result in anions which are negatively charged
• Too few electrons result in cations which are positively charged
• Atoms may transfer or share electrons, molecule formation is help together by electron interaction
• Atomic attraction with electron transfer are called primary or strong bonds

Ionic Bond

• The Ionic Bond is the electrostatic force of attraction between two oppositely charged ions
• Ionic bonds join metals to non-metals
• Features poor ductility and low thermal and electrical conductivity

Covalent Bond

• Electrons are shared by atoms to form molecules
• is also called a shared bond, joins non-metals
• has Low electrical conductivity
• Diamond is a form of covalently bonded carbon and has high hardness

Metallic Bond

• Metallic Bonds have few electrons in their outer orbits, thus cannot complete outer shell of self-mated atoms
• Available electrons are shared by all atoms in contact
• They provide attractive forces to hold the atoms together
• Metallic bonds join metals to metals
• Results in generally high thermal and electrical conductivity

Crystals and Grains

• Crystals are materials with a repeating arrangement of atoms
• Single crystals have a single grain so the array of atoms are not interrupted
• Poly crystals have much grains and structures are basic to the material properties

Materials Deformation

• Includes tensional, compressional and shear stresses

Tensile Test: Stress-Strain Curve

• The stress-strain curve measures:
• Ultimate tensile strength
• Fracture strength
• Yield strength
• Young's Modulus

Materials are tested

• Engineering stress is the ratio of applied load to the original cross-sectional area
• Engineering strain the change against original length
• Linear elastic behavior occurs when the specimen elongates proportionally to the load and returns to its original shape when unloaded
• Permanent deformation occurs when yield stress is reached

Imperfections in Crystal Structure of Metals

• Actual strength of metals is typically lower than calculated strength due to defects
• The crystal structure discrepancy is due to defects and imperfections which are categorized by:
• Point defects which include vacancy in atoms
• Linear defects which include dislocation
• Planar imperfections like the grain boundaries
• Volume imperfections like voids

Imperfections

• Self-interstitial and substitutional atoms creates imperfections
• Vacancy, and interstitial impurities are imperfection factors

Imperfections in The Crystal Structure of Metals

• Defects in a metal's orderly atomic structure are called Dislocation
• A slip plane containing dislocation requires less shear stress and allows slip than does a plane
• Dislocation defects are categorized to edge and screw types

Dislocation:

• It is a linear crystalline defect around atomic misalignment
• Plastic deformation corresponds to the motion of dislocations in response to shear stress
• Dislocations can be introduced during solidification or plastic deformation

Edge Dislocation Motion

• An edge dislocation moves with shear stress perpendicularly placed to its line
• Plastic deformation is caused in Cubic & hexagonal metals by plastic shear or dislocation slips

####Screw Dislocation Motion

• Motion occurs with shear stress but defect line movement is perpendicular to the stress and the atom displacement moves in parallel

Dislocation Motion

• Movement result in the formation of a step on the surface of a crystal
• Dislocations line is moved with applied shear stress
• Edge: is moved in line
• Screw: is perpendicular

Grains and Grain Boundaries

• grain boundaries separate individual gains
• grain consists of single or polycrystalline aggregate like alloys
• grain size influences mechanical properties
• grain boundaries influence strength and ductility

Metals and Alloys

• Behavior depends on composition, structure, processing history, and heat treatment
• Heat treatment improves mechanical properties
• Crystal structure contains the same atoms with rare impurity atoms
• An alloy is one or more chemical elements, with one being metal

Recovery, Recrystallization, and Grain Growth

• Recovering properties happens by heating the metal with a specific temperature range for a time frame
• The called process is annealing

Events

• three occur consecutively with heating:
• Recovery happens below during recrystallization temperature
• Recrystallization a new equiaxed and strain-free grains are formed
• Grain growth where grains grow and exceed sizes when at temperature is elevated further

Cold, Warm and Hot Working

• Cold working is plastic deformation is carried out a normal temperatures
• Hot working is deformation with recrystallization temperatures
• Warm working happens with intermediate temperatures
• The homologous temperature is a ratio used to categorize deformation

Heat Treatment: Annealing

• Annealing restores a cold-worked or heat-treated alloy to its original property
• This will increase ductility and reduce hardness and strength
• 3 steps:
• Heating the work piece in furnace
• Holding it at a specific time
• Cooling in air or furnace

Design Considerations for Heat Treating

• Heat treating avoids problems that would cause cracking, distortion and lack of properties
• Avoid sharp edges
• Part should have uniformed thickness
• Large surfaces with cross sections are likely to wrap

Heat Treatment: Hardenability of Ferrous Alloys

• Capability of and alloy to be hardened through heat treatment is called hardenability
• Hardness is the resistance of scratching and identitfy
• Cooling rate dictates severity of media. Ranked below from high to low

1. Agitated brine
2. Still water
3. Still oil
4. Cold gas
5. Still air