Sample Solution on Small Scale Engine Design - MyAssignmentHelp

Question: Describe about the Small Scale Engine Design? Answer: Introduction In this project, we continue our designing process, as completed in the semester 1, with the manufacturer changes as specified.The project specifications in the part-1 of project were:a) Miniature two stroke, compression ignition engine (to be used in an Unmanned Arial Vehicle)b) Brake horse power = 0.06bhp (45W) when speed = 14,000rev/minc) Capable of driving a propeller of a 200mm x 100mm diameter pitchd) Drive shaft greater than 5mme) Air cooledf) Production of 500 engines per yearThe changes that our consultancy has been asked to incorporate are:a. Design changes for production of 2000, 5000, 10,000 engines per yearb. Assembly planning for i. Crankshaft assemblyii. Piston assemblyiii. Fuel line assemblyc. Process planning for crankcase, crankshaft, cylinder head or piston.d. Engine life cycle analysis. Designing Assembly Planning Crankshaft Assembly The crankshaft is the part which rotates in the main bearings, which is inside the crankcase. There are connecting rods are attached to throws. This is the area which is attached to offset, where the change of reciprocating motion of the piston into rotary motion takes place. Fig. 2: Crankshaft Assembly In this project, we have been asked to assemble the crankshaft assembly. Running the data given as thresholds on the CES EduPack, we have arrived at the conclusion to use Machining Process for the assembly. It has to be machined using stainless steel. Fig. 3: CES EduPack Machining Planning Its states that: PLANING is a process of machining category, which is used for removing metal from surfaces in vertical, horizontal, or angular planes. In this process, the work piece is reciprocated in a linear motion against single-point tools, which can be one or more. This planning process is most widely used for producing flat surfaces on large work pieces. But, the process can also be used to produce a variety of irregular shapes and contours, like helical grooves, deep slots, and internal guide surfaces. The machining processes which is used to remove metal from surfaces are called SHAPING and SLOTTING. They do this with a single-point tool mounted on a reciprocating ram. Shape Solid 3-D Non-circular prismatic Circular prismatic Physical attributes Roughness 0.4 - 25 m Range of section thickness 10 - 500 mm Mass range 0.01 - 100 kg Tolerance 0.013 - 0.5 mm Process characteristics Prototyping Discrete Economic attributes Relative equipment cost medium Labour intensity medium Economic batch size (units) 1 - 100 Relative tooling cost low Piston Assembly Fig. 4: Piston Assembly This has again been designed using Machining, in which turning, boring and parting process is used. Fig. 5: EduPack Details on Turning, Boring and Parting It states that: TURNING is the process that generates external surfaces of revolution. It does so by removing material from a rotating work piece, which is done using a single-tipped cutting tool. The rotory motio to the work piece is provided by chuck mounted which is gripped in a lathe. BORING is this same action applied to internal surfaces of revolution. It is commonly used process for finishing or enlarging holes or other circular contours. Although most boring operations are done on straight-through, simple holes (ranging upward in diameter from about 6 mm), tooling can be designed for holes with bottle-shaped configurations, boring blind holes and bores with undercuts, steps, and counter bores. The process of boring is used after drilling, which is done to increase dimensional accuracy and finish This is also done for finishing holes too large to be produced economically by drilling, like large pierced holes in forgings or large cored holes in castings. The process of PARTING is the process w here the separation of a turned object from the stock from which it was made by turning the section down to zero. Shape Circular prismatic Hollow 3-D Solid 3-D Physical attributes Tolerance 0.013 - 0.38 mm Mass range 0.001 - 5.5e4 kg Roughness 0.5 - 25 m Process characteristics Discrete Cutting processes Machining processes Prototyping Economic attributes Relative equipment cost high Relative tooling cost medium Economic batch size (units) 1 - 1e7 Fuel line Assembly Fig. 6: Fuel Line Assembly The fuel tank has to be manufactured by Seam Welding, according to EduPack. Fig. 7: EduPack details of Seam Welding It states that: In seam welding, circular wheel-like electrodes press the overlapping sheets to be welded together and while rolling conduct a series of high current-low voltage pulses to the work. These produce overlapping spot welds which become a continuous seam. No fluxes or filler material is required. The electrodes are made of low resistance copper alloy and are water-cooled. The carburettor has to be manufactured using High Pressure die casting. Fig. 8: EduPack details of High Pressure die casting It states that: In the process of PRESSURE DIE CASTING, molten metal is injected under high pressure into a metal die. This is done through a system of runners and sprues. During this solidification, the pressure is maintained. Then, the die halves are opened to inject the casting. As high pressures is involved here, the two die halves are held together by a high force. They are then locked with toggle clamps also. The dies are precision machined from heat resistant steel. They are then cooled with water. They often include several movable parts and are therefore expensive and complex. The die casting machines are of two types, which are generally used. They are: hot chamber and cold chamber. In the 'hot chamber' process, which is also known as gooseneck process, the molten metal is held in a furnace in which a gooseneck chamber is submerged. Upon each cycle, the gooseneck is filled with metal. It is then forced into the die. Because of the prolonged contact between the injection system and the meta l, this process is restricted to zinc-base alloys. In the 'cold chamber' process, metal is melted in a separate furnace. It is then transported to the die casting machine. The cold chamber process can be used for a variety of alloys, whereas the hot chmaber process cannot. Die castings cannot be heat-treated because of internal porosity. The process is very competitive for producing large quantities of thin-walled castings. Shape Non-circular prismatic Hollow 3-D Solid 3-D Circular prismatic Physical attributes Roughness 0.8 - 1.6 m Mass range 0.05 - 15 kg Tolerance 0.15 - 0.5 mm Range of section thickness 1 - 8 mm Fig. 9: Cost modelling of High Pressure die casting What-if Analysis We have here analysed the two materials that can be used to manufacture crankcase. They are: Aluminium C355.0 Aluminium S319.0 Material Processing footprint for Aluminium C355.0: (according to CES EduPack) General properties Designation Al-alloy: C355.0, T6 UNS number A33350 Density 2.7e3 - 2.73e3 kg/m^3 Price * 1.69 - 1.85 USD/kg Composition overview Composition (summary) Al/4.5-5.5Si/1.0-1.5Cu/.4-.6Mg/.2Fe/.2Ti/.1Mn/.1Zn Base Al (Aluminium) Composition detail Mn (manganese) 0.1 % Si (silicon) 4.5 - 5.5 % Ti (titanium) 0.2 % Zn (zinc) 0.1 % Al (aluminium) 92 - 94 % Cu (copper) 1 - 1.5 % Fe (iron) 0.2 % Mg (magnesium) 0.4 - 0.6 % Mechanical properties Bulk modulus 68.3 - 71.8 GPa Poisson's ratio 0.33 - 0.343 Shape factor 28 Yield strength (elastic limit) 193 - 276 MPa Young's modulus 70 - 73.6 GPa Shear modulus 27 - 28.4 GPa Hardness - Vickers 90 - 95 HV Fatigue strength at 10^7 cycles 62 - 97 MPa Tensile strength 255 - 345 MPa Elongation 1 - 3 % Fatigue strength model (stress range) * 42.9 - 80.2 MPa Parameters: Stress Ratio = 0, Number of Cycles = 1e7 Compressive strength 193 - 276 MPa Flexural strength (modulus of rupture) 193 - 276 MPa Fracture toughness * 18 - 23 MPa.m^1/2 Mechani cal loss coefficient (tan delta) * 1e-4 - 0.002 Thermal properties Maximum service temperature 130 - 200 C Minimum service temperature -273 C Melting point 545 - 620 C Thermal expansion coefficient 22.3 - 23.5 strain/C Thermal conductivity 152 - 165 W/m.K Specific heat capacity 963 - 1e3 J/kg.K Latent heat of fusion * 384 - 393 kJ/kg Durability: fluids and sunlight Weak alkalis Acceptable Strong alkalis Unacceptable Water (fresh) Excellent Strong acids Excellent Organic solvents Excellent Water (salt) Acceptable UV radiation (sunlight) Excellent Oxidation at 500C Unacceptable Weak acids Excellent Primary material production: energy, CO2 and water CO2 footprint, primary production 11.9 - 13.2 kg/kg Water usage 125 - 375 l/kg Embodied energy, primary production 209 - 231 MJ/kg Material processing: energy Conventional machining energy (per unit wt. removed) * 4.16 - 4.6 MJ/kg Non-conventional machining energy (per unit wt. removed) * 31.8 - 35.2 MJ/kg Metal powder forming energy * 7.97 - 8.81 MJ/kg Vaporization energy * 17 - 18.8 MJ/kg Casting energy * 2.39 - 2.64 MJ/kg Forging, rolling energy * 3.02 - 3.34 MJ/kg Material processing: CO2 footprint Vaporization CO2 * 1.36 - 1.5 kg/kg Forging, rolling CO2 * 0.242 - 0.267 kg/kg Metal powder forming CO2 * 0.638 - 0.705 kg/kg Conventional machining CO2 (per unit wt. remo ved) * 0.333 - 0.368 kg/kg Casting CO2 * 0.143 - 0.158 kg/kg Non-conventional machining CO2 (per unit wt. removed) * 2.54 - 2.82 kg/kg Material Processing footprint for Aluminium S319.0: (according to CES EduPack) Designation Al alloy: S319.0; LM21-M (cast) UNS number A03190 Density 2.78e3 - 2.84e3 kg/m^3 Price * 1.65 - 1.81 USD/kg Composition overview Composition (summary) Al/6Si/4Cu/Zn Base Al (Aluminium) Composition detail Si (silicon) 6 % Cu (copper) 4 % Al (aluminium) 90 % Zn (zinc) 0 % Mechanical properties Hardness - Vickers 85 - 90 HV Fatigue strength at 10^7 cycles * 55 - 65 MPa Bulk modulus 65 - 86 GPa Poisson's ratio 0.32 - 0.36 Young's modulus 71 - 75 GPa Yield strength (elastic limit) 124 - 137 MPa Tensile strength 190 - 210 MPa Compressive strength 124 - 137 MPa Shear modulus 26 - 28 GPa Shape factor 38 Flexural strength (modulus of rupture) 124 - 137 MPa Elongation 1.9 - 2.2 % Fatigue strength model (stress range) * 41.2 - 50.8 MPa Parameters: Stress Ratio = 0, Number of Cycles = 1e7 Fracture toughness * 24 - 26 MPa.m^1/2 Mechanical loss coefficient (tan delta) * 1e-4 - 0.002 Thermal properties Thermal conductivity 119 - 123 W/m.K Minimum service temperature -273 C Melting point 520 - 615 C Thermal expansion coefficient 20.5 - 21.5 strain/C Specific heat capacity 944 - 982 J/kg.K Maximum service temperature 130 - 200 C Latent heat of fusion 384 - 393 kJ/kg Durability: fluids and sunlight Strong acids Excellent Weak acids Excellent Water (salt) Acceptable Organic solvents Excellent Water (fresh) Excellent UV radiation (sunlight) Excellent Strong alkalis Unacceptable Weak alkalis Acceptable Oxidation at 500C Unacceptable Primary material production: energy, CO2 and water CO2 footprint, primary production 11.9 - 13.2 kg/kg Embodied energy, primary production 209 - 231 MJ/kg Water usage 125 - 375 l/kg Material processing: energy Casting energy * 2.3 - 2.54 MJ/kg Forging, rolling energy * 2.41 - 2.67 MJ/kg Conventional machining energy (per unit wt. removed) * 4.08 - 4.51 MJ/kg Metal powder forming energy * 7.65 - 8.46 MJ/kg Vaporization energy * 16.4 - 18.1 MJ/kg Non-conventional machining energy (per unit wt. removed) * 30.8 - 34 MJ/kg Material processing: CO2 footprint Forging, rolling CO2 * 0.193 - 0.214 kg/kg Casting CO2 * 0.138 - 0.152 kg/kg Conventional machining CO2 (per unit wt. removed) * 0.326 - 0.361 kg/kg Vaporization CO2 * 1.3 1 - 1.45 kg/kg Metal powder forming CO2 * 0.612 - 0.677 kg/kg Non-conventional machining CO2 (per unit wt. removed) * 2.46 - 2.72 kg/kg Conclusion The changes has been done according to the requirements. The analysis has been done on CES EduPack, taking the number of parts manufactured as 200, 500 and 10,000. The cost threshold has been set to $100 in each case. According to the CO2 footprint, the material suitable for use in crankcase of the crankshaft assembly should be Aluminium S319.0., though it is not they fuel efficient is terms of energy produced, but eco audit suggests Aluminium S319.0 for low carbon dioxide emission. References George E. Dieter (1997). "Overview of the Materials Selection Process", ASM Handbook Volume 20: Materials Selection and Design. Ashby, Michael (1999). Materials Selection in Mechanical Design (3rd edition ed.). Burlington, Massachusetts: Butterworth-Heinemann. ISBN 0-7506-4357-9. "Material Grapher". Materials Digital Library Pathway MatDL.org. "Granta Design". Granta Design. Ashby, Michael F. (2005). Materials Selection in Mechanical Design. USA: Elsevier Ltd. 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