BJTM 2023 MANUFACTURING TECHNOLOGYCHAPTER 2:FUNDAMENTAL OF MATERIALS FOR MANUFACTURING

*INTRODUCTIONAt the end of this lecture, student will be able to:classify types of engineering materialselaborate different types of material propertiesexplain typical use of materialsexplain the method of material selection for particular manufacturing processes

*Materials in Manufacturing Most engineering materials can be classified into one of three basic categories: Metals steel, copper, aluminumCeramics clay, alumina, glass (silicon)Polymers plastic, ABS, polyethylene Their chemistries are different, their mechanical and physical properties are dissimilar These differences affect the manufacturing processes that can be used to produce products

*In addition to the three basic categories, there are: Composites nonhomogeneous mixtures of the other three basic types rather than a unique category example, airplane wings,Figure 1.3 Venn diagramof three basicMaterial types plus composites

5Metals: The Most Important Engineering Materials TodayThey have properties that satisfy a wide variety of design requirements The manufacturing processes by which they are shaped into products have been developed and refined over many years

*Why Metals Are ImportantHigh stiffness and strength can be alloyed for high rigidity, strength, and hardness Toughness capacity to absorb energy better than other classes of materials Good electrical conductivity Metals are conductors Good thermal conductivity conduct heat better than ceramics or polymers Cost the price of steel is very competitive with other engineering materials

*Starting Forms of Metals used in Manufacturing ProcessesCast metal - starting form is a castingWrought metal - the metal has been worked or can be worked after castingPowdered metal - starting form is very small powders for conversion into parts using powder metallurgy techniques

*Classification of Metals Ferrous those based on ironSteelsCast ironsNonferrous all other metals Aluminum, magnesium, copper, nickel, titanium, zinc, lead, tin, molybdenum, tungsten, gold, silver, platinum, and othersSuperalloys

*SteelAn alloy of iron containing from 0.02% and 2.11% carbon by weightIt is the carbon content that turns iron into steel Often includes other alloying elements: manganese, chromium, nickel, and molybdenumSteel alloys can be grouped into four categories: Plain carbon steelsLow alloy steelsStainless steelsTool steels

*Stainless Steel (SS)Highly alloyed steels designed for corrosion resistance Principal alloying element is chromium, usually greater than 15%Cr forms a thin impervious oxide film that protects surface from corrosion Nickel (Ni) is another alloying ingredient in certain SS to increase corrosion protection Carbon is used to strengthen and harden SS, but high C content reduces corrosion protection since chromium carbide forms to reduce available free Cr

*The Light Non Ferrous Metals: Aluminum and MagnesiumAluminum and magnesium are light metalsThey are often specified in engineering applications for this featureBoth elements are abundant on earth, aluminum on land and magnesium in the sea

*TungstenProperties: highest melting point among metals, one of the densest, also the stiffest (highest modulus of elasticity) and hardest of all pure metalsApplications typically characterized by high operating temperatures: filament wire in incandescent light bulbs, parts for rocket and jet engines, and electrodes for arc welding Also widely used as an element in tool steels, heat resistant alloys, and tungsten carbide

*CeramicsA compound containing metallic (or semi-metallic) and nonmetallic elements. Typical nonmetallic elements are oxygen, nitrogen, and carbonFor processing purposes, ceramics divide into:1. Crystalline ceramics includes:Traditional ceramics, such as clay (hydrous aluminum silicates)Modern ceramics, such as alumina (Al2O3)2. Glasses mostly based on silica (SiO2)

*Polymers A compound formed of repeating structural units called mers, whose atoms share electrons to form very large moleculesThree categories: Thermoplastic polymers - can be subjected to multiple heating and cooling cycles without altering their molecular structureThermosetting polymers - molecules chemically transform (cure) into a rigid structure upon cooling from a heated plastic condition3.Elastomers - exhibit significant elastic behavior, i.e. rubber

*SOME OF IMPORTANT THERMOPLASTICSImportant Commercial Thermoplastics are:Acetals: Automotive door handles, appliance hard ware and machinery components.Acrylics: Tail light lenses of automobiles, optical instruments, aircraft windows. (Excellent transparency)ABS: Components for automobiles, pipes and fittings.Polycarbonate: PC used as safety helmets, housing for business machinesPolyesters: PE, used as fibers in apparels, blow molded containers.Polyethylene: PET, used to produce bottles, pipes and hard wares.,

*Composites A material consisting of two or more phases that are processed separately and then bonded together to achieve properties superior to its constituentsA phase = a homogeneous mass of material, such as grains of identical unit cell structure in a solid metalUsual structure consists of particles or fibers of one phase mixed in a second phase Properties depend on components, physical shapes of components, and the way they are combined to form the final material

*Properties of materials

Metal CeramicPolymerHigh densityLow densityVery low densityMedium to high melting pointVery high melting pointLow melting point

DuctileBrittleDuctile and brittle typesElectrical conductorElectrical insulatorElectrical insulatorThermal conductorThermal insulatorThermal insulatorOpaque (not transparent)May be transparentMay be transparent

*Typical use of materials

Types of materialTypical useMetals such as steels and NFM (Non Ferrous Metals)Industrial machineries such as mould, tools and part of machinery; automotive components etcPolymers such as TPConsumer products casing such as television, computers, etc; containers such as bottles, rubber productsCeramicsStructural parts such as bricks, tiles, etc; cooking wear, glass products etc.CompositesHigh technology products such as airplanes components, air jet components, etc

*Material selectionThe interdependence of materials and the manufacturing process must also be recognized.A change in material may require a change in the process.Improvements in processes will often lead to re-evaluation of the materials being processed.Improper processing of a well-chosen material may result in defective product.

*Procedure for material selectionSelection of an appropriate material and its subsequent process is a complex process.Usually, a manufactured product follows a sequence of activities:Design Material Selection Process Selection Production Evaluation Redesign (if necessary)Several methods have been developed for material selection

*Procedure for material selectionCase history method: Evaluating what has been done in the past orWhat is currently being done by the competitor.Duplication or modification of the materials and method of manufacture

*Procedure for material selectionModification of existing product:The objective is to reduce cost, improve quality or overcome a problem or defectEx: A customer may request the same product but require capability of operating at high temperature.Development of entirely new product

*Procedure for material selectionThe first step in material selection process is to define the needs/ requirement of the product.There are three major needs of a product:Shape and geometryProperty requirementsManufacturing concerns

*Procedure for material selectionShape and geometry:What is the relative size of the component?How complex is the shape?How many dimensions must be specified? How precise?Etc.

*Procedure for material selectionProperty requirement:How much strength?Are there any electrical requirements?Are there any optical requirements?Are there any surface treatment/ process needed?What will be the effect of temperature of the product?Is there any preferred color?Etc.

*Procedure for material selectionManufacturing concern:How many components are to be produced? At what rate?What is the level of quality?Are there any assembly or disassembly required?What are the largest and smallest thickness?Etc

*Other factors to considerMaterial availabilityThe material must be ready in the required size, quantity or shapedMaterial costEtc.

*Compatibility charts of materials and processesY Can be used0 Can be used but has difficultyBlank Not recommended

ProcessMaterialIronSteelAluminumCopperNickelZincRefractory MetalsSand CastingYYYYY0Die CastingY0YInvestment CastingYYY0Powder MetallurgyYY0Y0X

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