Two Important Principles for Each ME EN 282 Chapter (From Students)
Two important principles for each ME EN 282 Chapter (from students)
Chapter 1: Structure of Metals
1. Grain size has great influence over strength of metals
2. Dislocation motion governs yield, strength, and failure type.
Chapter 2: Mechanical Behavior, Testing, and Manufacturing Properties of Materials
1. Stress-strain curves: true vs. engineering, modulus of elasticity.
2. Manufacturing: plasticity
Chapter 3: Physical Properties of Materials
1. Understanding what physical properties are: density, melting point, specific heat,
thermal conductivity, thermal expansion, corrosion resistance, electrical, magnetic &
optical properties.
2. Materials should be chosen according to these properties.
Chapter 4: Metal Alloys: Their Structure and Strengthening
1. You change structure and strength of the materials by various processes, i.e.,
quenching.
2. As you cool the material, you can get different properties as well.
Chapter 5: Ferrous Metals and Alloys: Production, General Properties, and Applications
1. Iron is made out of iron ore, glass & placed in furnace.
2. Steel properties are determined by the alloying elements.
a. Which alloys work well with iron?
Chapter 6: Nonferrous Metals and Alloys: Production, General Properties, and Applications
1. Most common: aluminum, magnesium & copper.
2. Non-ferrous alloys have many desirable properties: strength toughness, hardness,
ductility, creep, oxidation, high strength-to-weight ratios.
a. Non-ferrous materials corrode very easily. Chromium helps prevent corrosion.
b. Titanium has a high strength-to-weight ratio & is very good in high temperature
environments.
Chapter 7: Polymers: Structure, General Properties, and Applications
1. Compared to metals, polymers are characterized by lower density, strength &
modulus of elasticity.
2. Prop of polymers depend on moelecular weight, structure (branched, linear, crosslinked)
crystallinity.
a. Thermosets
i. Hard & more brittle, can only be set once.
b. Thermoplastics
i. Can be re-melted to form a new shape.
Chapter 8: Ceramics, Graphite, Diamond, and Nanomaterials: Structure, General Properties, and Applications
1. Ceramics are compromised of metallic & non-metallic elements. Mostly covalent &some ionic bonding - very brittle.
2. Can withstand high temperatures, compressive stresses, hardness, elastic modulus,but low thermal expansion, low thermal conductivity; good chemical inertness.
Chapter 9: Composite Materials: Structure, General Properties, and Applications
-In a composite, have fibers of various materials: glass, boron
-Putting the fibers in a matrix will support the fibers and protect them from the
environment, reduce crack propagation.
-Advantages of matrix materials:
-Something that is strong because of the fibers, but they are only strong in one
direction, so we put the fibers in all directions
Disadvantages:
-Expensive
-Difficult to design and manufacture
Chapter 10: Fundamentals of Metal Casting
-The way the metal is poured and the rate is cooled affect the grain size & structure
-Design of the mold can lead to various defects: shrinkage, porosity, uneven cooling
rate.
-Basic Principle: you can melt material and pour it into a mold to form a specific shape
Chapter 11: Metal-Casting Processes and Equipment
-Casting is very versatile: cheap/expensive, produce many parts or only a few.
-Expendable mold casting, loss foam
-Without proper design of casting, lots of flaws can form.
- Different parts of the mold:
-flask, drag, pouring basin, pouring cup, runner system, sprue, gates, risers, core
Chapter 12: Metal Casting: Design, Materials, and Economics
-Casting parts should be designed to eliminate: sharp corners, angles, consistent
thickness, eliminate large flat areas
-Production rate, equipment rate, die & labor costs and materials used dictate the
casting process
Chapter 13: Metal-Rolling Processes and Equipment
- Rolling processes produce unilateral & anisotropic properties
-Rolling is used to reduce the cross-section area of piece & can be produced and
various temperatures.
Chapter 14: Metal-Forging Processes and Equipment
-Forging produces parts w/ higher strength, improved toughness, dimensional accuracy,
reliability & service
-defects appear in workpiece quality, billet/preform shape, geometry.
-Strength: very fine grain structure, placing your material in compression.
-Very good in the world of fatigue and resistance
Chapter 15: Metal Extrusion and Drawing Processes and Equipment
-Extrusion is pushing a billet through a die. Affected by angle, lubrication, & temperature
-Drawing is pulling a material through a die into a wire, rod, or tube.
Chapter 16: Sheet-Metal Forming Processes and Equipment
-Punching, blanking, bending, deep drawing, spinning
-Combination of these techniques can produce complex parts
-Among the most versatile of all operations
-Because of thin materials used, spring back is a function of yield stress, modulus of elasticity
Chapter 17: Powder-Metal Processing and Equipment
-Power metallurgy process: power production, blending, compression, sintering,
finishing operations
-Other processes that can be used w/ metallurgy: injection molding, forging, rolling,
extrusion, ceramic molds
-You can get more homogeneous mixtures. Properties will be reasonably uniform
throughout the material.
-Expensive
-Strength runs at about 80% of pure material
Chapter 18: Ceramics, Glasses, and Superconductors: Processing and Equipment
-Glasses can be formed by processes similar to plastics & metals
-more attention paid to shrinkage & cracking
-Glass of uniform thickness can be formed by rolling, drawing, or floating
Chapter 19: Plastics and Composite Materials: Forming and Shaping
-Plastics can be formed in all the same ways as metals
-different heat requirements & finish properties
-Polymer matrix composites
-directional properties by inserting fibers
Chapter 20: Rapid-Prototyping Processes and Operations
-Used to identify errors in the design
-Nice way to create a prototype for marketing
-Great for making blanks for molds
-3 main categories:
-subtractive
-additive (adding layer by layer)
-virtual (CAD systems)
-Produce a 3D object you can hold & touch in order to examine
Chapter 21: Fundamentals of Machining
-Tool life depends on forces, temperatures
-Tool life can be increased by running at optimal speeds and machining appropriate
Materials
Chapter 22: Cutting-Tool Materials and Cutting Fluids
-Table 22.2
-Cutting fluids: used as coolants, lubricants. Help reduce thermal distortion, forces,
machine surface corrosion.
-Carbides & diamonds are used in tools now
Chapter 23: Machining Processes: Turning and Hole Making
-Turning, facing, boring, drilling, tapping
-Produce internal/external profiles
-Parts that are machined originally came form forging, casting, metallurgy & then you
-Round parts: lathes
Chapter 24: Machining Processes: Milling, Broaching, Sawing, Filing, and Gear Manufacturing
-Tool bit is doing most of the turning while the part stays still
-Milling
-Very economical in producing a variety of shapes and sizes
Chapter 25: Machining Centers, Machine-Tool Structures, and Machining Economics
-Machining centers advantages
-higher production right, higher efficiency
-Vibration, chatter are important to look at
-work piece dimensional accuracy
-Automate the material handling system
-Make tool changing very easy
Chapter 26: Abrasive Machining and Finishing Operations
-workpiece has high hardness/brittle
-Made from aluminum oxide
Chapter 27: Advanced Machining Processes
-Suitable for hard/brittle materials and complex shapes
-Decrease production time, higher dimensional accuracy
-Chemical, electric, water jet, etc.
Chapter 28: Fabrication of Microelectronic Devices
1.Uses layered etching multi-layer processes to create microelectronics components
2. Silicon can be doped to provide desired electrical conductivity materials.
Chapter 29: Fabrication of Microelectromechanical Devices and Systems and Nanoscale Manufacturing
1. Uses same layered etching processes used to create microelectronics components
2. Applies same layering processes to create mechanical components (MEMS)
Chapter 30: Fusion-Welding Processes
1. Melts materials to be joined and sometimes a filler material also.
2. Weld strength is substantially less than native materials and defects are common.
Chapter 31: Solid-State Welding Processes
1. Uses a variety of processes to join materials, often using electrical resistance.
2. Processes are generally more expensive.
Chapter 32: Brazing, Soldering, Adhesive-Bonding, and Mechanical-Fastening Processes
1. Joining techniques such as soldering apply melted filler materials to joint components, with strength of bond dependent on surface area of bonding material.
2. Techniques and processes depend on application.