IE330/ME366 ? Spring Semester 2009 Areas of Emphasis for Final Exam Chapter 3 - Mechanical Properties Three types of static stresses to which materials can be subjected Perfectly Elastic- fractures rather than yielding to plastic flow. Brittle materials such as ceramics, cast irons, and thermosetting polymers. Not good candidates for forming operations Elastic And Perfectly Plastic-stiffness defined by E. K=Y and n=0. Metals behave this way when heated and recrystalilize rather than strain hardening during deformation. Elastic And Strain Hardening- obeys Hook?s Law in the plastic region. K>Y, n>0 Stress-Strain Relationships - Tensile Properties; concepts and quantitative Know the graphs on pg. 46 Engineering and True stress-strain; strain/work hardening; Flow curve Engineering Stress- Oe= F/Ao Engineering Strain- e= (L-Lo)/Lo True Stress- instantaneous Area True Stain- e = ln(L/Lo) Flow Curve = O= K(true strain)^n Testing, failure, mechanical properties Bending/ Flexural Test- test the strength of materials, two supports and load applied at its center of material Torsion Test- as torque is increased the the tube deflects by twisting Cleavage- failure mode associated with ceramics and metals operating at low service temperatures, which separation rather than slip occurs. Tranverse Rupture Strength- (1.5FL)/bt^2)- strength value from test Brindell Hardness- metals and nonmetals of low to medium hardness. Uses hardened steel or cemented carbide ball for indention. 10mm diameter Equation on pg. 52 Rockwell Hardness- cone shaped indenter. Diameter 1.6 or 3.2 mm Vickers Hardness- pyramid shaped indenter made of diamond Knoop Hardness- same as vikers but the pyramid had a length to width ratio of 7:1 Durometer- measures the elastic deformation of rubber and similar flexible materials by pressing an indenter into the surface of object. Ceramics (Vickers and Knoop) Elasticity/plasticity Elasticity- returns to regular shape after stress is removed. Plasticity- ability to be shaped or formed Fluidity- Reciprocal of Viscosity Newtonian Fluid- constant viscosity Testing, failure, mechanical properties Idealized categories of stress-strain relationships Viscosity and viscoelasticity - definitions; Newtonian and non-Newtonian fluids Pseudoplastic- decreasing viscosity with increasing shear rate Viscoelasticity- determines the strain it experiences when subjected to combinations of stress and temp over time. Effects of temperature on properties As temp increases the viscous behavior becomes more and more prominent relative to elastice behavior, becoming more like a fluid Homework Chapter 5 - Dimensions, Tolerances, and Surfaces Dimensions, tolerances Dimension- linear or angular sizes of a component Tolerance- limited allowable variation from the dimension Bilateral- variations permitted in pos and neg directions frm nominal dim Unilateral- variations permitted in only 1 direction, either pos or neg Limit Dimension- consist of max and min dimensions allowed Surface Roughness Average of the vertical deviations from the nominal surface over a given length Manufacturing processes and tolerances; manufacturing processes and surfaces +-0.05mm tolerance or better Geometric Dimensioning and Tolerancing Parts and assemblies Datums Types of Tolerances Feature Control Frames ? understand structure Maximum Material Condition - definition and use Homework and examples Chapter 6- Metals Emphasis on concepts, reasons for selection Alloys Definitions Pg. 91 Phase ? what are phases and phase diagrams; NOT responsible for phase diagrams for specific alloys Phase- homogenous mass of material, metal which the grains all have the same crystal lattice structure. Diagram- graphical representation of phases of metal alloy as a function of composition and temperature Solid solution Substitutional solid solution- atoms of the solvent element are replaced in its unit cell by the dissolved element. Interstitial solid solution- atoms of the dissolving element fit into the vacant spaces between base metal atoms in the lattice structure. Intermediate phase- when the amount of the dissolving element in the alloy exceed the solid solutibity limit of the base metal, then the second phase forms which is the intermediate phase. Basic constituents, basic properties Ferrous ?contains low amounts of carbon, pig iron and steel, and alloys of iron with other metals(such as stainless steel) Steels - plain carbon, low-alloy, stainless steels, tool steels Plain Carbon- carbon as the principal alloying element- 10XX Low- iron-carbon alloy, higher strength, hardness, hot hardness, wear resistance, toughness. Heat treatment improves properties Stain- group of highly alloyed steels designed to provide high corrosion resistance, principal alloying element is chromium. Tool- usually high alloyed steels designed for use of cutting tools,dies,and molds. Improved hardenability, reduced distortion during heat treatment, hot hardness, and enhanced toughness Cast irons-iron alloy containing from 2.1% to 4% carbon and from 1-3% silicon Non-ferrous- include metal elements and alloys not based on iron. Cant match strength of steels, however the corrosion resistance and strength to weight ratios make up for that. Aluminum-abundant and found in land, not easily extracted frm original state. Principal aluminum ore is bauxite. Bayer Process and Electrolysis Magnesium-abundant and found in sea. Lightest of the structural metals. In all processing of magnesium small particles of metal oxidize rapidly, and care must be take to avoid fire hazards Copper-one of the oldest metals known. Natural deposits are hard to find therefore the copper is now extracted from ores that are mostly sulfides. Low electrical resistivity. Noble metal, meaning corrosion resistant. Copper is the most important metal. Ore is chalcopyrite Nickel-corrosion resistant, superior high temp properties of its alloys. Pentlandite is the most important ore of nickel. Flotation tech used to separate the sulfides from other minerals mixed with the ore. Titanium-fairly abundant in nature. principal ore is rutile. Chapter 8 Polymers Definition of polymers-compound consisting of long-chain molecules, each molecule made up of repeating units connected together, most based on carbon and are considered organic chemicals. Polymerization Addition-AKA chain polymerization- exemplified by polyethylene, the double bonds between carbon atoms in the ethylene monomers are induced to open so that they will join with other monomer molecules. Step-AKA condensation polymerization- two reacting monomers are brought together to form a new molecule of the desired compound, a byproduct of the reaction is also produced, typically water Categories: thermoplastic and thermosetting polymers; elastomers Thermoplastic-solid at room temp, and become viscous liquids at temps of only a few hundred degrees. Easily and economically shaped. Commercially most impostant. Can be subjected to heating and cooling cycle repeatedly w/o significant degradation of polymer Thermosetting- can?t tolerate repeated heating cycles. When initially heated they soften and flow for molding. Elevated temps produce a chemical reaction that hardens the material into a infusible solid, degrading and charring the polymer Elastomers-rubbers, exhibit extreme elastic extensibility when subjected to relatively low mechanical stress Differences between them Commercial and technological importance Basic mechanical properties; Limitations compared to metals Effect of crystallinity on mechanical properties As crystallinity is increased in a polymer, so are the density, stiffnes, strength, toughness, and heat resistance. If the polymer was transparent in the amorphous state, it becomes opaque when partially crystallized Amorphous (glassy) Chapter 10 - Fundamentals of Metal Casting What is casting? Ingot and shape casting? process which molten metal flows by gravity or other force in to a mold where it solidifies in the shape of the mold cavity Ignot-large casting that is simple in shape and intended for subsequent reshaping by processes such as rolling or forging. Shape- production of more complex geometries that is much closer to the final desired shape of the part or product. Why is casting an important category of manufacturing processes Because a variety of shape casting methods are available, making it one of the most versatile manufacturing processes. Open and closed molds Open- simply poured until it fills the open cavity Closed- a passageway, gating system, is provided to permit the molten metal to flow from outside the mold into the cavity. Far more important Expendable and permanent molds and their advantages and disadvantages Expendable- mold must be destroyed to remove the casting, ex sand casting more intricate geometries are generally possible wit expendable molds Permanent- used over and over again to produce many castings part shapes are limited by the need to open the mold. high economical advantages in production Superheat? Heat of fusion? Superheat-difference between the temp at pouring and the temp at which freezing begins. Also known as the amount of heat that must be removed from the molten metal between pouring and when solidification commences. Heat of Fusion- amount of heat required to solidify the metal from the liquid state. high heat of fusion tends to increase the measured fluidity in casting Solidification- transformation of the molten metal back into the solid state. Three steps of shrinkage liquid contraction during cooling prior to solidification contraction during the phase change from liquid to solid, called solidification shrinkage thermal contraction of the solidified casting during cooling to room temperature. Chills? a way to encourage directional solidification there are internal and external chills Internal-small metal parts placed inside the cavity before pouring so that the molten composition similar to the metal being poured External- metal inserts in the walls of the mold cavity that can remove heat from the molten metal more rapidly than the surrounding sand in order to promote solidification. Risers? reservoir in the mold that serves as a source of liquid metal for the casting to compensate for shrinkage during the solidification. Must be designed to freeze after the main casting in order to satisfy its function. Chvorinov?s rule and importance to the design of casting molds? Tts= Cm(V/A)^n Homework problems Chapter 11 Metal Casting Processes Expendable Mold Casting Sand Casting - basic steps; molds and cores; mold making, casting; effect of buoyancy Steps- pouring molten metal into mold, allowing to solidify, then breaking up the mold to recover the casting, casting is cleaned and inspected, sometimes heat treatment is required to improve properties. Molds-cavity of mold is formed by packing sand around a pattern and then removing the pattern by separating the mold into two halves. Molds also include the gating and riser system. If casting is to have internal surfaces then a core must be included in the mold Expanded Polystyrene Process - steps, advantages/disadvantage Investment Casting - steps, advantages/disadvantage Permanent Mold Casting Advantages/disadvantages Die casting - basic description; advantages/disadvantages Casting defects Product design considerations Homework Chapter 13 Plastics - Shaping Processes Properties important in polymer melts Die swell - what is it and what causes it Understand processes Extrusion Injection molding Compression molding Blow molding Product Design Guidelines for Plastics Chapter 18 Fundamentals of Metal Forming What is metal forming Stress-strain relationship ? review Figures 3-3, 3-4, 3-5 Strain hardening, strength coefficient, strain hardening exponent Flow curve, flow stress Temperature ranges; cold, warm and hot working; advantages and disadvantages of each Strain rate effects Homework Chapter 19 Bulk Deformation Processes in Metal Working Commercial and technological importance Rolling Describe Rolling mill configurations; advantages Thread rolling ? advantage over producing by machining Forging Three types - describe Examples of upset forgings Extrusion Describe Forward and reverse extrusion Homework Chapter 20 Sheet Metal Work Major categories of sheet metal processes What is cutting? Shearing, blanking, punching (Illustrations might be best answers)? Importance of Clearance? What is bending? Springback and its cause? What is drawing? Drawing ratio? Redrawing? Homework Chapter 21 - Theory of Metal Machining Why important Basic types of machining Cutting tools; basic tool geometry Cutting conditions Chip formation ? orthogonal model Relationships between rake angle, shear angle, chip thickness, shear strain, friction angle Comparison of orthogonal chip formation with actual Application of orthogonal model to turning Force Balances and force relationships ? understand derivation of equations Forces of tool on chip Forces of work on chip Measurable forces Understand derivation of equations (21.9) through (21.12) Merchant's Equation - implications and conclusions Homework Chapter 22 Machining Operations and Machine Tools Basic shape categories ? rotational and prismatic Two ways of creating part shape ? explain Turning Operations ? general Equipment Work holding devices Milling Interrupted cutting ? nature of cutting with milling cutter Difference in peripheral and end milling Difference in up milling and down milling Equipment Chapter 23 - Cutting Tool Technology Failure modes Tool Life Tool wear ? general Locations of wear Wear mechanisms Stages of wear Taylor tool life equation ? n and C parameters Tool materials Basic tool materials; advantages/disadvantages Properties for selection and temperature dependence Most valuable property of high speed steel Difference in steel-cutting and nonsteel-cutting cemented carbides Tool Geometry ? basic definitions Homework Chapter 24 Economic and Product Design Considerations in Machining Machinability ? general definition; a few possible measures of performance used to assess machinability Tolerance and surface finish and their relationship with cost Product design considerations in machining ? be familiar with these factors Chapter 25 Grinding and other Abrasive Processes Grinding- any material, veryfine finishes, close tolerances Grinding wheels Materials ? AlOxide-steel, BoNitr-toolsteel,siliconcarbide-nonferrous, diamond-glass Bonding Material ? ceramics, silicate, rubber, resinoid, shellac, metallic Application guidelines ? section 25.1.3 Chapter 26 Nontraditional Machining and Thermal Cutting Processes Nontraditional ? important bc can use new materials, complex geometries, avoid surface dam. Mech Energy ? high velocity streams to cut workpart Ultrasonic ? abrasives low amp high freq oscillation (glass,ceramics,steel, Ti) Non-round holes, or holes on a curved axis, Waterjet Cutting ? cut narrow strips in textiles, automated CNC Abrasive WJC ? AlOxide, siliconO2, and garnet(silicate) Thermal Processes ? material removed by fusion or vaporization (damaging) finishing reqd Electric Discharge ? sparks to melt metal away (only conductor workpieces) Wire Electric Discharge ? small dia electrode wire to cut kerf. Ideal for stamp dies (thin cuts) Chapter 39 Numerical Control and Industrial Robotics Numerical Control-form of programmable automation in which the mechanical actions of a piece of equipemt are controlled by a program containing coded alphanumeric data. What is Numerical Control History-John Parsons and Frank Stulen at Parsons Co. in Michigan in 1940?s Components of an NC system-1)part program2)machine control unit3)processing equipment Coordinate Systems and Motion Control 1 Point-to-point vs. 2 continuous path systems-1-move workhead to a programmed location with no regard for path taken to get to location. 2-provides continuous simultaneous control of more than one axis, thus controlling the path followed by the tool relative to the part. 1 Absolute vs. 2incremental positioning 1-workhead locations are always defined with respect to origin. 2-next workhead position is defined relative to present location NC Positioning Systems Motion hardware components-workstations, material handlilng system, central control computer. 1 Open vs. 2 closed loop systems; feedback-1uses a stepping motor to rotate the leadscrew. 2-uses servomotors and feedback measurements to ensure desired position. Programming-Manual part programming, computer assisted part programming, CAD/CAM assisted part programming, manual data input Non-machining applications-1)tape laying machines and filament winding machines for composites 2)welding machines 3)component insertion machines in electronics assembly 4)drafting machines 5)coordinate measuring machines for inspection. Benefits of numerical control- reduce nonproductive time, lower manufacturing lead times, simpler fixturing, greater manufacturing flexibility, improved accuracy, and reduced human power. Industrial robotics Definition of industrial robot-general purpose programmable machine peossessing certain anthropomorphic features. Robot anatomy Joints and links-provides relative movement between two parts of the body. Arm & body functions-moves to cover all axis Wrist functions- simple handling and assembly tasks involving vertical motions. Not always at the end of the arm. End effectors-special tooling that connects to the robots wrist end to perform a specific task. Robotic motion control categories (limited sequence, etc.)-limited sequence, playback with point to point, playback with continuous path, intelligent control. Programming ? leadthrough- involves ?teach by showing? in which the manipulator is moved by the programmer through the sequence of positions in the work cycle. Work situations that indicate potential beneficial use of robot in place of human worker ? know several-1)work environment too hazardous for humans 2)work cycle is repetitive, 3)work is performed at a stationary loc. 4)part or tool handling would be difficult for haunts, 5)it is multishift operational. Accuracy/Precision of motion Chapter 40 Group Technology and Flexible Manufacturing Systems Group technology Definition and reason for use-an approach to manufacturing in which similar parts are indentified and grouped together in order to take advantage of their similarities in design and production. Approach-in production, group similar parts together to be made. Classification and coding Part families- a group that possess similarities in geometric shape and size, or in the processing steps used in their manufacture What is classification and coding?-most are one of the following: systems based on part design attributes, systems based on part manufacturing attributes, systems based on both design and manufacturing attributes. Benefits of a well-designed system-facilitates formation of part families, permits quick retrieval of part design drawings, reduces design duplication, promotes design standardization, improves cost estimate and cost accounting. Cellular manufacturing What is it?- to fully exploit the similarities among parts in a family, production is organized using machine cells designed to specialize in making particular parts. Benefits and problems + promotes standardization of tooling, fixturing, and setups, material handling is reduced, production scheduling is simpler, manufacturing lead time is reduced, work in progress is reduced, process planning is simplified. Problems: rearranging production machines, identifying part families Composite part of a part family- a hypothetical part that includes all of the design and manufacturing attributes of the family. Flexible manufacturing systems What are they and what are their components; functions of central control computer- a highly automated group technology machine cell, consisting of a group of processing stations, interconnected by an automated material handling and storage system, and controlled by an integrated computer system. NC part programming - development of NC programs for new parts introduced into the system Production control - product mix, machine scheduling, and other planning functions NC program download - part program commands must be downloaded to individual stations Machine control - individual workstations require controls, usually CNC Layout Applications: machining, assembly, inspection, sheet metal processing, forging Benefits:higher machine utilization, reduce work in process, lower manufacturing lead times, and greater flexability in production scheduling Chapter 41 Production Lines Production lines Product variations- can be designed to cope with variations in product models 3 types: single model line, batch model line, mixed model line. Forms of material transfer manual and mechanized: continuous transfer sys., synchronous transfer sys., asynchronous transfer sys. (moves independently.) Manual assembly lines- human workers at workstations 1problem =line balancing Line balancing (general terms, not calculated times)- workers must have equal amount of work. Automated production lines Transfer lines- lines that perform processing operations. Automated assembly systems- one or more workstations that perform assembly operations, such as adding components and or fixing them to the work unit. Chapter 44 ? Quality Control Quality is the degree of excellence which a thing possesses. Random vs. Assignable Cause Variation- Random-Caused by factors such as human variability, variations in raw materials, machine vibration, and so on. Assignable Cause-An exception from normal operating conditions due to operator mistakes, defective raw materials, tool failures, machine malfunctions, and so on Process Capability- Defined as ( 3 standard deviations about the mean output value (a total of 6 standard deviations) PC Index Taguchi Loss Function- Taguchi defines quality as "the loss a product costs society from the time the product is released for shipment" Robust Design ? what is it?- A basic purpose of quality control is to minimize variations. Taguchi calls these ?noise factors?. (A design in which the product's function and performance are relatively insensitive to variations in design and manufacturing parameters) Statistical process control-The use of various statistical methods to assess and analyze variations in a process Control charts for variables- A process that is out of statistical control significant changes in: Process mean, and/or Process variability two principal types of control charts for variables: x chart (?x-bar? chart) - indicates how the process mean changes over time R chart ? monitors the range of each sample A point outside control limits 8 or more consecutive points on same side of mean (trend indicators that are still within control limits) Chapter 45 Measurement and Inspection Explain the difference between the terms "measurement", "inspection", and "gaging" What is "accuracy"? What is the relationship between "accuracy", "precision", and "systematic error"? What is "Rule of 10" in metrology? What is meant by the terms "resolution", "calibration", and "stability" as applied to measuring instruments? Laboratory Inventor - basic approaches to creation of parts and assemblies; will not ask about various "buttons" Measurement Lab - understand how measuring tools work; be able to read them Injection Molding - General principles CNC Milling ? review general approach Problems Equations will be provided Review homework, example and test problems
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