Cuff Alternator Block - Assignment Example

Running Head: VICTA 2 STROKE ENGINE Student’s Name: Course Code: Lecture’s Name: Date of presentation: An engine block refers to an integrated structure comprising the reciprocating cylinder among other associated structures and components such as crankcase, intake and exhausts orifices and coolant passages. An engine block is indeed the core of the engine, housing nearly all the parts and components needed for proper functioning of the engine. The block is typically organized in a ‘V’ inline architecture, or horizontal configuration. Since the engine blocks are crucial component of an IC engine, it must fulfill certain physical and functional requirements and obligations. These include among other things, housing all the major and minor engine components and fluids, ease of manufacture, maintenance and service, withstand extreme conditions of temperature and pressure present during combustion operation process, as well as lasting during the better part of the powered machine. Modern engines have come to their optimal development although more research is still being undertaken. These researches are aimed at increasing power, resistance to wear, durability, and efficiency by minimizing cost and difficulty of manufacture. The type of material used in manufacturing engine blocks For many days, cast iron alloys have been widely used in making engine blocks. This is probably due to its low cost, strength and ability to withstand wear. However, as the engines increase in size, new materials have been developed to reduce the overall engine weight, as well as increasing wear resistance and strength. Due to its low comparable weight, cast aluminum alloy is now widely adopted for the manufacture of engine blocks especially for petrol engines. For an engine to satisfy the functional and operational requirements listed above, the engineering construction material used in the engine block manufacture must possess high modulus of elasticity, abrasion resistance, corrosion resistance, high strength. High strength is of particular concern in engines with higher compression ratios such as diesel engines 17:1. However, the material should have low thermal expansion to withstand increased operating temperatures and pressures. This will prevent engine failure at such high operating conditions. The material should also have low density so as not unnecessarily increase the weight of the engine. The material should also exhibit good workability i.e. high castability and machinability, higher cost of manufacture is evident in harder materials. The alloy material selected should have high damping properties to absorb the quaking and shuddering of the adjacent moving parts. Materials used in Engine block manufacture Depending on the functional requirement of a particular engine block, engineers have used iron and aluminum alloys to produce these vital engine components. Cast iron is chosen due to superior mechanical properties, readily availability and low cost of production. Aluminum alloys have low weight and thus when combined with cast iron a more competitive material is developed. Compacted graphite cast iron is often preferred over gray cast iron due to its light weight and higher strength coefficient. Aluminum alloys have also high machinability properties, low weight and lower cost as compared to the grey cast iron. The two alloys widely used are A356 and 319. Al- 319 contains between and 85.8 and 91.5 percent Al, 5.6- 6.6 per cent silicon, 3- 4 percent copper and traces of titanium, manganese, and zinc. Manufacturing the engine Block Casting In making Vicka 2 engine blocks, aluminum alloy A356 is used. The chemical composition of the material is 91.1- 93 per cent Aluminum, 6.5- 7.8 per cent silicon, 0.25- 0.45 per cent magnesium and traces of copper, titanium, iron and zinc. The material has a relatively low modulus of elasticity at 73 GPA. Fig.1. Typical Victa 2 Stroke Engine Mounted on a Lawn Mower The casting method used is lost-form casting method. This method is not only efficient but more reliable for casting of engine block as compared to green sand casting. Polystyrene beads are first put in pre-expanded to create distinct block moldings that will be bound together to form final mould. Once fully connected together, ceramic liquid is sprayed to the assembly. The coated form engine block is the filled with casting sand, then compacted and finally dipped in the molten metal alloy. Fig. 2: Pouring Molten Metal into the Mould from ladle Upon cooling the sand is taken out from the metal ally casting, cleaned and taken through a series of heat treatment process to improve on its mechanical properties. The oil and coolant passages are finally machined in the block. Fig. 3. Typical Green Sand Casting method Fig. 4. Typical Lost Foam Casting Method Correct order of operation with reasons Engine Block Disassembly All Vicka 2 engine blocks are first visually inspected for any casting defects. This is done prior to their disassembly from the mould and before the onset of the remanufacturing operations of the block. The block and other parts are carefully removed from the mould and visually inspected for any damage and possible cause of failure. The water and oil passage plug are removed to achieve optimum results while carrying out the thermal cleaning process. Any repairable faults detected at this stage are attended by skilled casting repair technicians. i. Thermal cleaning of the engine block This process is aimed at giving the Victa 2 stroke engine a close dimensional precision, taking it to a new level of dimensional accuracy. Heaters arte used to emit a uniform and controlled thermal energy which is uniformly distributed within the heat jacket. Thermal cleaning process is aimed at distributing heat evenly within the chamber that preventing the engine block parts from warping, overheating or possibly melting down. To achieve the block is heated to temperature range of between 340- 427 Celsius in an Ace RKE 230. ii. Shot Blasting process The engine block is then shot blasted using stainless steel shots to remove any undesired surface contamination such as irregularities and rust during the remanufacturing process. This process aims at achieving a clean surface finish for ease in detection of surface flaws and subsurface casting imperfection at the quality inspection stage. The block is also subjected to a peening process to improve its compression strength. Metal pellets shots like fine pall pen hammers are struck on the surface of the engine block. All cast iron blocks are subjected to this treatment prior to the onset of preliminary inspection. The process is carried out by use of AR HB41® is widely used for cast iron engine blocks to assist in more accurate Magnetic Particle Inspection. iii. Magnafluxing process MPI is the ultimate method of testing for surface imperfection and cracks in ferrous parts of engine block. This process as part of the quality control procedure aims at reassuring the potential Victa 2 stroke engine customers of the quality of the products. This is the final stage for the Iron based engine blocks before pressure test. Victa 2 stroke engine cat aluminum engine blocks are however separately cleaned, tested and checked for surface cracks. iv. High Pressure Wash Test This is the first of step of remanufacturing for a passed aluminum engine block after casting process. The engine block is subjected to a cleaning process in an AXE SW20 OS spray gun. This spray removed all dirt, oil and other foreign material inside the freshly casted block. This is vital for accurate inspection. v. Ultrasonic Cleaning of the engine block This is the second cleaning process of a cast aluminum engine block. The ultrasonic cleaning process is able to get to the deepest cavity of the block in internal areas which would otherwise be inaccessible with mechanical spray agitation. The extreme pressure force involved in ultrasonic cleaning helps in breaking down the ionic and mechanical bonds that bind together tiny particles to the cast surface. Once the block is thoroughly cleaned, it is passed over to the pressure testing stage. vi. Pressure testing of the Engine block A delta pressure tester is used for pressure testing Victa 2 stroke cat engine blocks. This is aimed at checking the pin holes after dye testing and magnafluxing processes have been completed. Any cracks and flaws that were not detected in the previous tests are easily detected at this stage. Pressure testing process helps in reaffirming the integrity of all Victa 2 stroke engine block castings. vii. Engine Block Honing Process A Sunnen CH-100 ® honing machine is used in the remanufacturing of the Victa 2 stroke engine block. The machine corrects any inherent distortion that is caused by cap stretch and warpage. This process is crucial prior to cylinder boring process. viii. Engine |Block Boring A Rottler F54X® boring machine is used in cylinder boring for Victa 2 stroke engine. This is due to its hard chromed spindles and large diameter. To control the cutter position feed rate, a precision ball screw. The machine can be programmed to precision cycles of 0.005mm. ix. Engine Block Milling Winona Van Norma M3000® milling machine is used for both cast iron and cast aluminum engine blocks to achieve the desired Ra surface finish. The quality of surface finish is always depended on the type of gasket used. The milling machined used in milling Victa 2 stroke engine blocks use cubic boron nitride (CBN) milling cutters, which are second to diamond in hardness. The discarded metal chips produced help in carrying out the heat produced during the cutting process thus leading to an excellent surface finish and dimensional accuracy. The quality of surface finish is check using the Mitutoyo SJ-301® to check the Ra value of surface finish. After milling, the engine block is ready now for rod reconditioning. x. Rod Reconditioning of the Engine Block A Sunnen LBB- 1600 ® honing machine is used to produce the straight and round honed surfaces for precision assembly. xi. Engine Block Cleaning Before final assembly, the block undergoes high pressure and ultrasonic washing. The prior is aimed at removing any dirt debris that may have been lodged on the engine block surface during the remanufacture machining process. Ultrasonic cleaning cavitation used is aimed at cleaning internal areas which cannot be reached during spray mechanical agitation. xii. Engine Block Assembly The complete Victa 2 stroke engine block is now ready for final assemble where connection rods, rings, pistons, lifter camshaft, bearings are assembled into the engine block. Each block is the fitted with the appropriate oil restrictors, relief valves, oil plugs and oil plugs. \the crankshaft is installed onto the engine block with high quality and precise bearings. Every journal clearance is inspected using plastigauge. New appropriate rings are installed onto the piston and together they are installed into the cylinder bores, cam bearings and other timing components are installed, inspected and double checked by quality technicians and assembly manager. Cylinder heat is then fitted with proper bolts and Victor head gaskets or Felpro gasket. Push rods, lifters and rocker arms are fitted and finally adjusted to required position. Seal integrity is then accurately checked for each cylinder head so as to avoid ant water or compression leaks. The oil pump is the primed at this point. A final inspection is carried out by an assembly manager or an equivalently qualified technician. Every Victa 2 stroke engine is supplied with installation manual among other enclosed installation and operational bulletins. Victa 2 stroke engine is packed in a wooden pallet that protects the vulnerable parts against damage. The pallet is wrapped with a suitable material to protect the engine from harsh weather conditions. Critical parts of the engine block Critical parts Cylinder Head- this is the top covers of the cylinder head thereby forming the combustion chamber. On the cylinder head, the valves and in some cases the cylinder head and camshafts are located. The cylinder head are made in such a way to boost air-fuel mixture turbulence or swirl. Pistons- Piston assembly transmits force from its power stroke to the crankshaft. Piston have ring that maintain a perfect seal to prevent escape of heat and pressure. Connecting rod- The part connects the piston with the crankshaft. This is achieved by use of gudgeon pin or piston ring. Crankshaft- The crankshaft converts the reciprocating motion of the rotary motion. Connecting rods are fitted onto the connecting rods in offset throws Non- critical Parts Fuel pump: this refers to the device that bring in fuel to the carburetor Spark Plug: this refers to an electric device that induces a “spark” to ignite the air/ fuel mixture I the engine Piston rings: they are fitted on the piston sleeve to prevent the escape of compressed air- fuel mixture from the combustion chamber. Valves: Valves are parts of engine that helps to control the rate and amount of intake air and exhaust to and from the engine combustion chamber. Fig. 4: Typical Parts of a 2- Stroke Engine Block Bibliography Dempsey, P.K (2009). Two- Stroke Engine: Repair and maintenance, Laxmi Publications New York Sawyer, C. (2003). Cast in foam,” Automotive Design & Production. New York. Victa 2 engine manual Vintage Mowers. (n.d.). Retrieved September 14, 2012, from http://www.vintagemowers.net/mower_stationary_engine.php Walshaw, T.D. (1997), Diesel engine design (2nd ed.), London, England: George Newnes Read More

Materials used in Engine block manufacture Depending on the functional requirement of a particular engine block, engineers have used iron and aluminum alloys to produce these vital engine components. Cast iron is chosen due to superior mechanical properties, readily availability and low cost of production. Aluminum alloys have low weight and thus when combined with cast iron a more competitive material is developed. Compacted graphite cast iron is often preferred over gray cast iron due to its light weight and higher strength coefficient.

Aluminum alloys have also high machinability properties, low weight and lower cost as compared to the grey cast iron. The two alloys widely used are A356 and 319. Al- 319 contains between and 85.8 and 91.5 percent Al, 5.6- 6.6 per cent silicon, 3- 4 percent copper and traces of titanium, manganese, and zinc. Manufacturing the engine Block Casting In making Vicka 2 engine blocks, aluminum alloy A356 is used. The chemical composition of the material is 91.1- 93 per cent Aluminum, 6.5- 7.8 per cent silicon, 0.25- 0.45 per cent magnesium and traces of copper, titanium, iron and zinc.

The material has a relatively low modulus of elasticity at 73 GPA. Fig.1. Typical Victa 2 Stroke Engine Mounted on a Lawn Mower The casting method used is lost-form casting method. This method is not only efficient but more reliable for casting of engine block as compared to green sand casting. Polystyrene beads are first put in pre-expanded to create distinct block moldings that will be bound together to form final mould. Once fully connected together, ceramic liquid is sprayed to the assembly.

The coated form engine block is the filled with casting sand, then compacted and finally dipped in the molten metal alloy. Fig. 2: Pouring Molten Metal into the Mould from ladle Upon cooling the sand is taken out from the metal ally casting, cleaned and taken through a series of heat treatment process to improve on its mechanical properties. The oil and coolant passages are finally machined in the block. Fig. 3. Typical Green Sand Casting method Fig. 4. Typical Lost Foam Casting Method Correct order of operation with reasons Engine Block Disassembly All Vicka 2 engine blocks are first visually inspected for any casting defects.

This is done prior to their disassembly from the mould and before the onset of the remanufacturing operations of the block. The block and other parts are carefully removed from the mould and visually inspected for any damage and possible cause of failure. The water and oil passage plug are removed to achieve optimum results while carrying out the thermal cleaning process. Any repairable faults detected at this stage are attended by skilled casting repair technicians. i. Thermal cleaning of the engine block This process is aimed at giving the Victa 2 stroke engine a close dimensional precision, taking it to a new level of dimensional accuracy.

Heaters arte used to emit a uniform and controlled thermal energy which is uniformly distributed within the heat jacket. Thermal cleaning process is aimed at distributing heat evenly within the chamber that preventing the engine block parts from warping, overheating or possibly melting down. To achieve the block is heated to temperature range of between 340- 427 Celsius in an Ace RKE 230. ii. Shot Blasting process The engine block is then shot blasted using stainless steel shots to remove any undesired surface contamination such as irregularities and rust during the remanufacturing process.

This process aims at achieving a clean surface finish for ease in detection of surface flaws and subsurface casting imperfection at the quality inspection stage. The block is also subjected to a peening process to improve its compression strength. Metal pellets shots like fine pall pen hammers are struck on the surface of the engine block. All cast iron blocks are subjected to this treatment prior to the onset of preliminary inspection. The process is carried out by use of AR HB41® is widely used for cast iron engine blocks to assist in more accurate Magnetic Particle Inspection. iii.

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