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76816689-Manufacturing-

Nov 08, 2014

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Manufacturing Processes This pageintentionally leftblankMANUFACTURING PROCESSES Second Edition U.K. Singh Professor & Head Department of Mechanical Engineering Kernla Nehru Institute of Technology SultanpUf (U.P. ) Manish Dwivedi B.E- . M.Tech. Deputy Director & Head Department of Mechanical Engi neering Aryavart Institute of Technology & Management Lucknow (U.P.) (Ex. Asstt. Director Bhabha Institute of Technology Kanpur DeMt) PtlI!lJStl""O O " ONE _LO NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS New Ddhi IJ3ngalorc ; Alloys 51 3.5 Copper Alloys 51 3.6 Zinc and its Alloys 54 3.7 Zinc Alloys 54 3.8 Lead and its Alloys 55 3.9 Tin and Alloys 55 3. 10 Nickel and it!> Alloys 56 3. 11 Other Advanced Materials/Alloys 57 3. 12 Dearing Materials 58 Objective (.AieMions & Answers 59 Short Answer Questioll5 61 Long Answer QueMions 62 4. METAL FORMING 63-104 4. 1 Metal Funni ng 63 4.2 Elastic and Plastic Deformations 63 4. 3 1I0t Working and Cold Working 64 4.4 Forgi ng 66 4. 5 Rolling 78 4.6 Wire Drawing 82 4.7 Tube Drawing 83 4.8 Making and Extrusion 86 CONTENTS 4.9 Prt..."is -work 90 4.10 Die & Punch Assembly 92 4.11 Shearing 93 4. 12 Shearing Dies 98 4.13 Deep Drawing 99 Objec:liw: Que,lions & Amwers 102 Shon Answer Que3fiOlU 103 Long Answer 104 5. CASTING 105-131 5. 1 Pattern 105 5.2. Dmfi 108 5.3 Moulding Materi al 109 5. 4 Moulding Sand 110 5.5 Mould Making with the Use of a Core 112 5.6 Gating System [13 5.7 Defects in Casting and Remedies 117 5.8 Cupola [2 [ 5.9 Die Casting 126 Objedive Que51ioru & Answers [29 Shorr Answer Questions 130 Long Answer Que5tions [ 30 6. MACIDl\'1NG 133-166 6. 1 Lathe: Introduction 133 6.2 Basic Working Principle of Lathe Machine [ 33 6.3 Operations Perfonned on Lathe Machine 134 6.4 Tenus Used in Lathe Machining [ 38 6. 5 Shaper 138 6.6 Planer 14 [ 6.7 Drilling Machine 145 6. 8 MiUi.ng 149 6.9 Grinding 157 Objedi l'e Que51imu & Answers 163 Shorr Answer Questions 164 Long Amwer Questions [65 7. WELDING 167-193 7. 1 Importance of Welding 167 7.2 Basic Concept of Welding [67 7.3 Classification of Welding Processes 168 7.4 Gas Welding 168 7.5 Electric Arc Welding 176 7.6 Between Ac and Dc Welding 182 7.7 Types of Joints 182 7. 8 Electric Resi stancc Welding 184 7.9 Types of Resistance Welding 185 7. 10 Soldering 188 7.1 1 Rrazing 7.12 Diflerence Between Soldering and Brazing Obje(:liw: Que, tiuns & AmweT5 Short Answer Questions /..,t.m;; Answer Questions 8. "MAl\'UFACTURING 8. 1 Importance of MalLTials 8.2 Manufacturing 8.3 hnpnrta nce of Manufacturing 8.4 Manufacturing Towards Technological & Socio-economic Developments 8.5 Classification of Manufacturing Processes 8.6 Plant Ulcation 8.7 Plant Layout 8.8 Types of Plant Layout 8.9 Shop Layout 8.10 Types of Pr0l1uc\ion 8. 11 Production and Productivity Objective C"JueuimlS & Amwers Short Answer Questions long Answer QuesliurlS 9. NON-METALLIC MATERIALS 9. 1 Wood 9.2 Cement Concrete 9. 3 Ct.TallliL"S 9.4 Rubber 9.5 Plastics : Introduction 9.6 Composite Materials Obje(:li I1e Que, tiuns & Amwers Short Answer Questions /..,t.m;; Answer Questions 10. MIf\CEILANEOUS PROCFBSFB 10. 1 History of Powdl.T Metall urgy 10.2 Main Characteristics of Powders 10.3 POWdl.T Metallurgy Process 10.4 App1ications of Powder Metal1urgy 10.5 Plastic 10.6 PlasticlPolymer Process ing 10.7 Galvanizing 10.8 Elcctmplat ing Objective Questiolls & Answers Shorr Answer Questions 1lIg Answer Questiolls Examination Papcr-(2008-09) & Sol ution Model Test Paper-I l\'lodcl Test Paper-II CONTENTS 188 189 189 191 192 195-208 195 195 196 196 196 198 199 200 203 205 206 207 208 208 209-227 209 212 2 14-216 2 18 224 226 226 227 229- 279 229 230 232 240 241 242 245 246 247 248 248 249 276 278 1.1 PROPERTIES OF MATERIALSDifferent materials possess different properties in varying degree and therefore behave in differentways under given conditions. These properties includes Mechanical properties, Electrical properties,Thermal properties, Chemical properties, Magnetic properties and Physical properties.A design engineer is interested in the behaviour of materials under load which is mechanical innature, for the design of machines & structures. Any material subjected to a load either deforms,yield, or break, depending upon the magnitude of the load.We are basically interested in knowing as to how a particular material will behave under appliedload i.e. in knowing the mechanical properties.1.2 STRESS-STRAIN DIAGRAMS(a) Stress-Strain Curves for Ductile MaterialsIf a mild steel bar of uniform cross-sectional area is subjected to gradually increasing axial tensileforce (generally is done in Universal Testing Machine) till failure of the bar occurs, and if we plotthe graph for stress and strain, the following curve (Fig. 1.1) may be obtained:The curve may be divided into following parts:Portion OA: This portion is absolutely straight,where the stress is proportional to strain and thematerial obeys Hookes law. The value of stressat point A is called proportional limit.Portion AB: In this portion, Hooks law is notobeyed, although the material may still be elastic.The point B indicates the elastic limit.Portion BC: In this portion, the metal showsan appreciable strain even without further increasein stress and the strain is not fully recoverable whenload is removed.Portion CC': Yielding commences in thisPROPERTIES OF MATERIALS1ABCFracture orBreaking StrengthUpper Yield PointElastic LimitProportionality LimitArea = Modulus of ResilienceElastic ZoneLower YieldPointStressOStrainMaximum orUltimate PointPlastic Zone(e)( ) Fig. 1: e Diag ram for Ductile Material C'EDF:\Sanjay\Final\After Ist Correction27\12\08Fig. 1: e Diagram for Ductile Material 2 MANUFACTURING PROCESSESF:\Sanjay\Final\After Ist Correction27\12\08portion and there is a drop of stress at the point C' immediately after yielding commences at C.The point C' is termed as lower yield point and C is called upper yield point.Portion C'D: After yielding has taken place at C', further straining takes place at this portionby increasing the stress and the stressstrain curve continues to rise up to the points D.Strain in this portion is about 100 times that of portion O to C. At the point D, the bar beginsto form a local neck. The point D is termed as ultimate tensile stress point. Ultimate stress iscalculated at this point.Portion DE: In this portion, the load falling off from the maximum until fracture at E takesplace. The point E is termed as fracture or breakingpoint and the corresponding stress is called breakingstress.(b) Stress Strain Curves for Brittle MaterialsMaterials which show very small elongation beforethey fracture are called brittle materials. The shape ofcurve for high carbon steel is shown in fig. 1.2 and istypical of many brittle materials such as G.I., concreteand high strength light alloys. For most brittle materialsthe permanent elongation (i.e. increase in length) is lessthan 10%.1.3 PRINCIPAL MECHANICAL PROPERTIESThose characteristics of the materials which describe their behaviour under external loads are knownas Mechanical Properties.The most important and useful mechanical properties are:1.3.1 StrengthIt is the resistance offered by a material when subjected to external loading. So, stronger the materialthe greater the load it can withstand.Depending upon the type of load applied the strength can be tensile, compressive, shear ortorsional.The maximum stress that any material will withstand before destruction is called its ultimatestrength (Point D as shown in Fig. 1.1).1.3.2 ElasticityElasticity of a material is its power of coming back to its original position after deformation whenthe stress or load is removed. Elasticity is a tensile property of its material.The greatest stress that a material can endure without taking up some permanent set is calledelastic limit (Point A as shown in Fig. 1.1.).1.3.3 Stiffness (Rigidity)The resistance of a material to deflection is called stiffness or rigidity. Steel is stiffer or more rigidthan aluminium.Stress( ) Strain(e)ConcreteCast IronHigh Carbon SteelFig. 2: e Diagram for Brittle Material PROPERTIES OF MATERIALS 3F:\Sanjay\Final\After Ist Correction27\12\08Stiffness is measured by Youngs modulus E. The higher the value of the Youngs modulus, thestiffer the material. E is the ratio of stress over strain and is given by the slope of line OA.1.3.4 PlasticityThe plasticity of a material is its ability to undergo some degree of permanent deformation withoutfailure. Plastic deformation will take place only after the elastic range has been exceeded, beyondpoint b.Plasticity is an important property and widely used in several mechanical processes like forming,shaping, extruding and many other hot and cold working processes. In general, plasticity increaseswith increasing temperature and is a favourable property of material for secondary formingprocesses.Due to this properties various metal can be transformed into different products of requiredshape and size. This conversion into desired shape and size is effected either by the application ofpressure, heat or both.1.3.5 DuctilityDuctility of a material enables it to draw out into thin wire on application of the load. Mild steel isa ductile material. The wires of gold, silver, copper, aluminium, etc. are drawn by extrusion or bypulling through a hole in a die due to the ductile property. The ductility decreases with increase oftemperature.The per cent elongation and the reduction in area in tension is