EM-226 Materials and Manufacturing Processes Instructor: Dr. Khurram Kamal Course Outline Engineering Materials • Desired Engineering Properties • Concept of Structure • Metals and Alloys • Phase Diagrams • Ceramics • Polymers • Composites • Semiconductors • Materials Characterization • Scanning Probe Microscopy • Non-Destructive Testing • Material Selection • Failure Analysis Manufacturing Processes • Manufacturing Systems • Foundry Practice and Modern Casting • Machining Processes • Welding • Brazing and Soldering • Non-traditional Manufacturing Processes • Heat Treatment • Electronic Fabrication • Rapid Prototyping Recommended Books • Elements of Material Science and Engineering by Van Vlack, Addison Wesley Publishing Co., Latest Edition2 • Introduction to Physical Metallurgy by Sidney H. Avner, McGraw Hill publishing Co., Latest Edition. • Engineering with Polymers by P.C. Powell. , Latest Edition. • Manufacturing Processes by Amstead, Begeeman and Ostwald, John Wiley & Sons, Latest Edition. • Materials and Processes in Manufacturing by E. Paul Degarmo, J. Black, Ronald A. Kosher. , 10th Edition. Marks distribution 50% Finals 30% First-term and mid-term 10% Quiz 10% Project Assignment + Report What is manufacturing? The word manufacturing, is derived from the Latin word “manu factus”, meaning made by hand. The word manufacture first appeared in 1567, and the word manufacturing appeared in 1683. In modern sense, manufacturing involves making products from raw materials by means of various processes, machinery, and operations, through a well-organized plan for each activity required. In a simpler way, manufacturing is a method/technique used to convert input in any form by the use of certain processes into a valuable output, going through a series of transition/value-adding processes. Types of manufactured goods • Manufactured goods are classified into two types • Producer Goods: are used to manufacture either producer or consumer goods. • Consumer Goods: are those purchased directly by the consumer or the general public. Why manufacturing? • Manufacturing is critical to a country’s economic welfare and standard of living to its people. • The standard of living in any society is determined, primarily , by the goods and services that are available to its people. • Manufacturing companies contribute about 20% of the GNP, employ about 18% of the workforce, and account for 40% of the exports of the United States. • In most cases, materials are utilized in the form of manufactured goods. Manufacturing Process • A manufacturing process converts unfinished materials to finished products, often using machines or machine tools. • For example, injection molding, die casting, stamping, arc welding, are commonly called processes or manufacturing processes. • The term process often implies a sequence of steps, processes, or operations for production of goods and services. • A machine tool is an assembly of related mechanisms on a frame or bed that together produce a desired result. • Generally, motors, controls, and auxiliary devices are included. • Cutting tools and workholding devices are considered separately. • A machine tool may do a single process (e.g., cutoff saw) or multiple processes, or it may manufacture an entire component. Machine sizes vary from a tabletop drill press to a 1000ton forging press. Olympic Medal MATERIAL CHARACTERISTIC AND SELECTION • In any finished product, it normally involves one or more than one type of material. Material can be obtained in either their original form or artificial form. There are lot of material involved in engineering application, alloys alone already consists of thousands of types. Not only alloys, the same with ceramics and polymers, their application is also very wide in engineering application. • Nowadays, more and more materials are being developed and researched to suit a specific application. Thus, an engineer has no choice but to know how to choose/select the best possible alternative for production to achieve their needs. Material Selection • Every produced product must be able to function as it is designed in a proper working condition for an acceptable period of time without failure. • Material selection play an important role in this, because selection of material will determine the characteristic, function, and also the cost of the product. • There are few crucial factors that are needed to be considered for material selection, these are: • Suitability of material in term of function usage of material in finished goods and also processing of the material to produce the product. • Reliability of material in term of ability/repeatability in producing desired dimension, surface texture, and tolerances. • Manufacturability of the material, the consideration if it can be formed/casted/welded/heat-treated/etc. easily as desired. • Processing effect towards the final characteristics of the material also should be considered, as it might affect the final • quality of the products, life of the products, and performance of the products. • Durability of the material is always in the consideration as it will somehow determine how long the product can last, especially in some areas like wear with time, compatibility with other material, safety factors, etc. • Availability of material and the ease to obtain supply of material in reasonable cost should be considered during material selection. This is to prevent your production from facing the possibility in shortage of materials, or running at a material costing. • Manufacturing cost should be reasonable in order to stay competitive with the competitors. Thus, various manufacturing processes should be considered in order to get the best possible methods that suit your production. • Waste elimination of material should be considered in order to avoid illegal disposable of material. If possible, go for some material which can be recycled. Engineering Materials • Materials used in engineering application can basically divided into three categories; • Metals • Ceramics • Polymers • Composites • The common metallic materials include iron, copper, aluminum, magnesium, nickel, titanium, lead, tin, and zinc as well as the alloys of these metals, such as steel, brass, and bronze. They possess the metallic properties of luster, high thermal conductivity, and high electrical conductivity; they are relatively ductile; and some have good magnetic properties. Physical and mechanical properties • A common means of distinguishing one material from another is through their physical properties. • These include such features as density (weight); melting point; optical properties (transparency, opaqueness, or color); the thermal properties of specific heat, coefficient of thermal expansion, and thermal conductivity: electrical conductivity; and magnetic properties. • In some cases, physical properties are of prime importance when selecting a material, however, material selection is dominated by the properties that describe how a material responds to applied loads or forces. • These mechanical properties are usually determined by subjecting prepared specimens to standard test conditions. • When using test results, however, it is important to remember that they apply only to the specific conditions that were employed. The actual service conditions of engineered products rarely duplicate the conditions of laboratory testing, so considerable caution should be exercised when applying test results. STRESS AND STRAIN • When a force or load is applied to a material, it deforms or distorts (becomes strained), and internal reactive forces (stresses) are transmitted through the solid. • For example, if a weight, W, is suspended from a bar of uniform cross section and length, the bar will elongate by an amount ∆L. For a given weight, the magnitude of the elongation, ∆L, depends on the original length of the bar. • The amount of elongation per unit length, expressed as e = ∆L /L, is called the unit strain. • Although the ratio is that of a length to another length and is therefore dimensionless, strain is usually expressed in terms of millimeters per meter, inches per inch, or simply as a percentage. • Application of the force also produces reactive stresses, which serve to transmit the load through the bar and on to its supports. • Stress is defined as the force or load being transmitted divided by the cross-sectional area transmitting the load. • The stress is S = W/A, where A is the cross-sectional area of the supporting bar. Stress • is normally expressed in mega pascals (in SI units, where a pascal is 1 newton per square meter) • meter) or pounds per square inch (in the English system). • In figure, the weight tends to stretch or lengthen the bar, so the strain is known as a tensile strain and the stress as a tensile stress. • Other types of loadings produce other types of stresses and strains. • Compressive forces tend to shorten the material and produce compressive stresses and strains. • Shear stresses and strains result when two forces acting on a body are offset with respect to one another. Tensile Strength Test Engineering stress-strain curve Strength Strength: is a material’s ability to withstand a force without failure. Depending on the type of forces applied, each and every material will have different strength level for different type of strength test. For example, a material might be having a good tensile strength but weak hardness strength. Elasticity • Elasticity :is the ability of material to return to its original condition whenever a force applied is released. Plasticity • Plasticity: is the ability of material to form under pressure and remain in its new shape whenever the pressure is released. Ductility • Ductility: is the ability of material to deform plastically without fracture. • Indication of ductility can be given by percentage reduction in the area i.e. (A o - A f )/ A o x 100% Brittleness • Brittleness: If a material fails with little or no ductility then it is said to be brittle. Thus brittleness can be seen as opposite to ductility.