GE 102 Manufacturing Technology PDF

GE 102 Manufacturing Technology  Introduction What is “MANUFACTURING”? the process of converting raw materials into products”. manufacturing can be defined as: - “the making of products from raw materials using various processes, equipments, operations and manpower accordi...

GE 102 Manufacturing Technology  Introduction What is “MANUFACTURING”? the process of converting raw materials into products”. manufacturing can be defined as: - “the making of products from raw materials using various processes, equipments, operations and manpower according to a detailed plan  Introduction Manufacturing Includes – Design of the product – Selection of raw materials – The sequence of processes through which the product will be manufactured. Any Product in the engineering industry will be manufactured in the below methods 1. By totally deforming the metal to the required shape. (Casting /Forming) 2. By joining two metals. (Welding) 3. By removing the excess material from the raw stock.(Machining)  TABLE OF CONTENTS Chapter 1 Engineering Materials Chapter 2 Casting Processes Chapter 3 Sheet-Metal Operations Chapter 4 Measuring Equipment's Chapter 5 Machining Processes Chapter 6 Plastic Forming Processes Chapter 7 Joining of Metals Chapter 8 Carpentry  Workshop Training Workshop Title 1 Turning 2 Welding 3 Casting 4 Sheet-Metal 5 Carpentry ENGINEERING MATERIALS  Introduction Engineering materials are those the engineer uses in his work Nearly all materials existing on and under the ground are used in engineering. Some of these materials are used directly as water, sand, etc., others need more or less treatment as iron ore, petroleum. Moreover, some materials are used alone in industry as wood, leather, etc., others are mixed together to produce other materials having specific properties as adding chromium to steel to improve its corrosion resistance  Ferrous metals 1- Steel – A combination of iron and carbon, steel is renowned for its strength and machinability. – It is widely used in construction, manufacturing and industrial metal fabrication. 2- Stainless Steel – Stainless steel is an alloy steel made with the addition of chromium to steel, which provides resistance against rust. 3- Carbon Steel – Carbon steel contains a high carbon content that is added to iron to create an exceptionally hard metal that is used for tools. 4- Cast Iron – Cast iron is a hard and wear resistant metal that is widely used for items including cookware, machine tools, engines, manhole covers and water pipes.  Non Ferrous metals 1- Aluminium – Lightweight and easy to machine, shape and weld – aluminium is used for a range of applications from food cans and cookware to aero plane parts and cars. 2- Copper – A good conductor of heat and electricity, copper is highly ductile and malleable. – It is widely used for electrical wiring as well as in appliances and vehicles. 3- Lead – With a low melting point and low tensile strength, lead is used in electrical power cables, batteries, pipes, and for paint. 4- Tin – Soft and malleable with a low tensile strength, tin is used as a coating to prevent steel from corroding. 5- Silver – Silver is used for a range of applications, including jewellery, electrical contacts and in mirrors. 6- Brass – Brass is used for fixtures and fittings including taps, hooks, and doorknobs, as well as being used for light fittings and screws, among other uses. 7- Gold – Used for jewellery, gold also has applications including within the medical industry, in computers and also electronics. 8. Zinc – A medium strength metal with a low melting point, zinc is used to galvanise iron and steel to prevent rusting.  Properties of Materials Classification of properties a) Physical properties: As the shape, dimensions, porosity, etc. b) Chemical properties: As the chemical composition, acidity, etc. c)Thermal properties: As the expansion, thermal conductivity, specific heat, etc. d) Electrical and Magnetic properties: As the electrical resistivity and conductivity, magnetic permeability, etc. e) Optical properties: As the color, light reflection and absorption etc. f) Acoustical properties: As the acoustic reflection and absorption, etc. g) Mechanical properties: They are the properties, which determine the behavior of the material under loads.  Main Mechanical properties of Materials 1-Elasticity: Is the ability of the material to restore its original shape or volume at once when the load is released. 2-Plasticity: Is the ability of the material to change its shape and dimensions under load and to keep the new shape and dimensions after the load is released.  Main Mechanical properties of Materials 3-Ductility: Is the ability of the material to deform (elongate) in static tension without failure. 4-Malleability: Is the ability of the material to change its shape under pressure (compressive load) without failure.  Main Mechanical properties of 5-Brittleness: Materials Is the ability of the material to fail without a noticeable in its dimensions. 6-Hardness: Hardness is the resistance of the material to penetration of another harder body Hardness ranges from super hard materials such as diamond, boron-carbide to other ceramics and hard metals to soft metals and down to plastics and soft tissues  Main Mechanical properties of Materials 7- Stiffness: Is the resistance of the material to any change of shape, it is measured by “Young’s modulus”. 8-Strength: Is the measure of the ability of materials to resist stresses (tensile, compressive, bending, shearing or torsion) under different conditions of loading (static and dynamic) and different temperatures. It is measured by the stress units σ (σ= force/area)  Main Mechanical properties of Materials 9-Toughness: Is the ability of the material to resist the dynamic load (i.e., to resist shocks) Toughness is the ability of a material to absorb energy and plastically deform without fracturing. ‫المتانة في علم المواد وعلم السبائك هو مقاومة المادة للكسر‬ ‫عندما تتعرض لإلجهادات‬  Terminology Stress is the measure of an external force acting over the cross sectional area of an object. Stress =force / area Engineering strain refers to the degree of deformation that a material withstands in the direction of applied forces in relation to its original length.  https://www.youtube.com/watch?v=4val- DD3GAA  Ensure quality Test properties Prevent failure in use Make informed choices in using material  Main Mechanical Tests of Metals 1- Tensile Test Tensile test is of a static type, it is the easiest mechanical test to perform. It is carried out to determine the strength and plasticity of materials. Moreover, the result of the tensile test gives a clear idea about the other mechanical properties of the material under test, mainly its ductility. For the tensile test to be carried out, we use a test specimen and a tensile test machine.  Tensile test specimens Test specimen: It is either round or flat shape cross- section. It ha s a standard shape and dimensions to be able to compare the obtained results. The mechanical properties in tensions are determined on the gauge length lo of the specimen. A tensile test machine  Tensile Test- Basic Principles An axial force applied to a specimen of original length (lo) elongates it, resulting in a reduction in the cross-sectional area from Ao to A until fracture occurs. The load and change in length between two fixed points (gauge length) is recorded and used to determine the stress-strain relationship. A similar procedure can be adopted with a sheet specimen.  Stress strain curve different regions i) Proportional limit (ii) Elastic limit (iii) Yield point (iv) Ultimate stress point (v) Fracture or breaking point Mechanical properties that are important to a design engineer differ from those that are of interest to the manufacturing engineer. In design, mechanical properties such as elastic modulus and yield strength are important in order to resist permanent deformation under applied stresses. Thus, the focus is on the elastic properties. In manufacturing, the goal is to apply stresses that exceed the yield strength of the material so as to deform it to the required shape. Thus, the focus is on the plastic properties.  The characteristic loads of stress strain curve 1- The elastic load Pe: Is the maximum load that causes elastic deformation only, i.e., deformation that disappears when the load is removed. the corresponding stress is the elastic limit e e = Po/Fo Pa or MPa. where Fo: Initial cross-sectional area of the specimen 1- The elastic load Pe Here is a line relation in the region of elastic deformation between stress and strain for metals and alloys. It confirms to the low of proportionality (Hook’s low): =E. Pa or MPa. E = / Where  (strain) = l/lo = (l1-lo)/lo The coefficient of proportionality E, called the modules of elasticity or Young’s modulus, characterizes the rigidity of a material, i.e., its resistance to elastic deformation in tension 2- The load at the yield point PB: Is the load at which the material elongates (deforms) without a noticeable increase in load. The corresponding stress is the yield stress ( σB) σ B = PB/Fo Pa or MPa. 3- The load at the ultimate strength PD: Is the maximum load which the specimen can withstand without failure. The corresponding stress is the ultimate strength (σD) σ D = PD/Fo Pa or MPa., Examples: 1- When testing a steel specimen of diameter D=10 mm., the maximum load Pu is 28400 N. Calculate the ultimate strength u. Solution: Fo = D2/4 = .102/4 = 78.5 mm2 = 78.5 x 10-6 m2 u = Pu/Fo = 28400/78.5 x 10-6 = 361.8 MPa. 2- Determine the elongation  of steel, if the specimen gauge lengths before and after tension lo and l1 are: 50 and 58 mm. respectively. Solution:  = (l1 – lo)/lo x 100 = (58-50)/50 x 100 = 16%  Hardness Test Hardness test is of a static type. It has found extensive applications in all branches of industry due to its rapidity, simplicity and its non-destructive character. Because the hardness of the metal is its resistance to penetration to another harder body, thus hardness test is applied by pressing a body in the metal under test, then evaluating its influence. There exist several hardness testing methods having the same principles but differ in the shape of the penetrating body.  Impact test The purpose of impact testing is to measure an object's ability to resist high-rate loading. The test measures the impact energy, or the energy absorbed prior to fracture. https://www.youtube.com/watch?v=tpGhqQvftAo What is Impact Energy? Impact energy is a measure of the toughness of a materials, i.e. materials resistance to fracture. When the striker impacts the specimen, the specimen will absorb energy until it yields. At this point, the specimen will begin to undergo plastic deformation at the notch. The test specimen continues to absorb energy at the plastic zone at the notch. When the specimen can absorb no more energy, fracture occurs  Types of impact test The most common methods of measuring impact energy are the: – Charpy Test – Izod Test The Charpy Test is the most commonly used on metals, it is also used on polymers, ceramics and composites CHARPY TEST IZOD TEST  The main differences between Izod and Charpy 1. Point of Strike : Point at which the hammer strike the specimen is different for both of them. In Izod test hammer strike at the upper tip of specimen while in Charpy test hammer strike at point of notch but in opposite direction 2- Direction of Notch: Face of specimen which faces the striker is different. The notch face in the izod test is facing the striker, fastened in a pendulum, while in the charpy test, the notch face is positioned away from the striker. 3-Type Of Notch: In hardness testing two types of notches are used V- notch and U-notch. In the Charpy method, there are two kinds of notches, the V-notch and the U-notch, while in the Izod method, there is V-notch is used 4-Specimen Dimensions: Even if you are testing the same material the test specimens have different dimensions for each test. The basic Izod test specimen is 75 x 10 x 10mm, the basic Charpy test specimen is 55 x 10 x 10mm.  Brittle and ductile materials Note: Tough materials absorb a lot of energy, whilst brittle materials tend to absorb very little energy prior to fracture The left specimen brittle— looks like it just snapped in half. The right specimen sample is ductile and bends without breaking into pieces.  Effect of temperature on impact energy Charpy V-notch impact tests: (a) temperature-dependent energy absorbed by molybdenum (Mo) samples during impact testing. The gray area indicates the brittle to ductile transition range (b-d). Samples fractured tested at room temperature (0.26 J), 100 °C (3.03 J) and 250 °C (8.64 J).  Fatigue Test. The failure of a metal under repeated reversing stresses is called fatigue. The resistance of a metal to fatigue failure is characterized by its fatigue limit Fatigue limit is the maximum stress the specimen can withstand without failure when this stress is repeated for a specified number of cycles (5x106 cycles for steels and 20x106 cycles for non-ferrous metals).  Fatigue Test The fatigue limit is usually determined by subjecting rotating specimen to repeated reversing stresses. At least six specimens must be tested to determine the fatigue limit. The first specimen is tested at a stress 1 and the number of cycles N1 at which failure is determined. The stresses 2, 3 etc., for the second and subsequent specimens are increased or reduced, depending on the number of cycles which caused the failure of the first specimen. The corresponding number of cycles N2, N3, etc., at which failure of such specimens occurs are determined too. The obtained results are plotted on a diagram Fig. 2.5. The horizontal section is a straight line and it is the maximum stress at which failure will not take place after an infinite number of loading cycles. S-N curve  https://www.youtube.com/watch?v=fGpTXrP VCRA  Questions for Review Engineering Materials 1- With the aid of flow chart, classify the engineering materials. 2- Define the following mechanical properties: Elasticity – Plasticity – Ductility – Brittleness – Hardness – Strength 3- What are the properties, taken in consideration, of choosing the engineering materials for manufacturing of the following products: Electric wire – Cutting tools – coking pans 4- State one metal used for manufacturing the following products: Car Tire – Cutting tools – Home Furniture – Electric wire – Medical instruments – Airplane hull. 5- When testing a steel specimen of diameter D=8 mm, the maximum elastic load Po=13000 N, if the specimen gauge length before and after test lo and l1 are 50 and 56 mm respectively. Calculate the modulus of elasticity E.