Saturday, June 27, 2009
Welcome to my blog once again. Igneous rocks originate deep in the earth. They erupt from volcanoes as magma and cool or solidify as they rise to the upper layers. Basalt is an igneous rock and so is granite, a very a hard rock often used in building. Pumice stone is a soft igneous rock that is ejected from volcanoes. As it cools, it often fills with so many air bubbles that it floats in water. Thank you.
Tuesday, June 16, 2009
Cold working does not necessarily mean literally what it says, it is true that many metal working processes are carried out at ambient temperature and these can certainly be termed cold working. However, metal working that is carried out at a temperature much higher than that revealing on the shop floor can also be described as cold working. The upper temperature limit of cold working varies with the metal and its metallurgical condition before working, but for steels cold working is generally considered to be between ambient and about 300 c. Significant work hardening takes place, and this severely limits the amount of plastic deformation that can occur before the material ruptures. To overcome this, if all the desired geometric changes cannot be achieved in one operation, the material must be partly changed and then annealed to eliminate the stress introduced by the work hardening. After annealing the work piece can then be safely subjected to a second cold working operation that will, hopefully, permit reduction to the final desired geometry. Cold working processes generally produce repeatable accurate components with a good surface finish. Unfortunately, cold working forces are very much higher than those required for hot working and unwanted residual stress are usually present after the final stages of working. If they are significant they tend to be released during subsequent machining of the part needs to be annealed before machining to remove these locked – in stresses. Any distortion that occurs during annealing is of no consequence as its geometrical effects will, of course, be removed during machining of the part. Thank you.
A metals recrystallization temperature is not quite as easy to determine as its melting point, because it is influenced by such factors as the level of internal stress that exists in the metal before heating, the alloys contained within the metal and its melting point .for many metals the recrystallization temperature is between 0.4 and 0.5 of the materials absolute melting point (k). Depending upon carbon content, for most steels it is generally in the region of 500 – 700 C. as can be seen from ambient, with aluminum being at just 150C. Thus, hot working does not necessarily imply that the temperature of the metal being worked is above ambient, although in most cases it is. And an important characteristic of hot working process is that the metal behaves in a perfectly plastic manner. Therefore the metal becomes neither internally stressed nor work hardened, so an unlimited amount of hot working can be performed on it without at a lower temperature. Hot working causes slag porosity and other inclusions inherent to some degree in most cast metal to be deformed and broken up into insignificantly small pieces. Also, the coarse granular structure typical of cast metals is realigned and a large number of smaller grains are formed. The effect of this is to impart a degree of toughness to the worked materials, although hardness and density are unchanged by hot working. Thank you.
Monday, June 15, 2009
Production Flow Analysis is a method identifying part families and associated grouping of machine tools. It does not use a classification and coding system and not use part drawing to identify part families. Instead, PFA used to analyze the operation sequence and machine routing for the parts produced in the given shop. It groups parts with identical or similar routing together. These groups then used to form logical machine cells in a group technology layout. PFA procedure is Data collection-Decide on the scope of the study and collect necessary data, Sorting of process routing – assemble the parts into groups to the similarity of their process routings, PFA chart- the processes used for each pack is displayed graphically on a PFA chart, Analysis-Rearrange the data of PFA chart into a new pattern which brings together packs with similar routings. Thank you
Thursday, June 4, 2009
material requirement planning is a computer based management information system designed to manage dependent demand inventory items in the transformation process of operations management.In other words MRP is defined as a planning technique, usually implemented by computer that translates the MPS of end products into a detailed schedule for the raw materials and parts used in those end products. The concept of MRP is relatively straightforward. Its implementation is complicated by the sheer magnitude of the data to be processed. The master schedule provides the overall production plan for the final products in terms of month – by – month deliveries. Each product may contain hundreds of individual components. Thank you.
Wednesday, June 3, 2009
Rzeppa Constant velocity joints are used when the angle of drive more than 30 degree .these types of joints are mostly used in front axle drive vehicles. Constant-velocity joints allow a rotating shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play. This joint has the input of a half shaft. The shaft is spilned at one end on which the inner spherical socket sits. The inner spherical socket and the outer spherical socket have grooves in which balls move. The outer spherical socket is connected to the output shaft. These joints are very strong, and are usually highly over specified for a given application. Thanks you.
External contracting brake consists of a drum, an external contracting brake band, linkages and operating lever. It is usually the hand brake of the automobiles. The drum is fitted with the transmission outputs shaft and rotates with it. The brake band having lining of frictional material encircles the brake drum. In order to hold the rotating brake band is contracted about the drum. In order to hold the rotating break drum by means of a lever and linkage. When the hand brake is applied, the brake band first tightens its grip on the drum. This stops the motion of the drum. The car is thus stopped. When the hand lever is released, the brake band losses its grip on the drum. The car is now ready for starting. Thank you.
Rotor pump is a automobile component. It is used to low pressure oil is converted to high pressure oil with help of two rotor lobes. One is rotor ‘A’ another is rotor ‘B’.’ A’ is the external rotor having the number of lobes one more than on the internal rotor ‘B’. The axes of rotation of the two rotors are different. So it causes the size of the spaces between them to vary. Rotor ‘B’ gets its drive from the engine and causes rotor ‘A’ to rotate along with it. The oil enters the pump through inlet port, as the rotor lobes are moving out of mesh. The oil is then transported from inlet to the outlet of the pump in the spaces between rotor lobes. The rotation reduces the clearance between the lobes. Then the oil is discharged under pressure as the lobes of the rotors move in to mesh at the outlet port. This type of pump is about 25% percent more efficient and compact than the gear pump. Also reduces noise in running. Thank you.
Tuesday, June 2, 2009
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics. I am explained in internal combustion engine radiator. The purpose of the radiator is to cool the water received from the engine. The radiator consists of three pats –upper tank, core and lower tank. Upper and lower tanks are joined by the core. The upper tank is connected to the water outlets from the engine jacket by rubber hose, and the lower tank is connected by another rubber hose to the jacket inlet through the pump. A drain cock is provided at the bottom of lower tank to remove water from the radiator. Thank you.
It is simple design in automobile component. Air cooling system is used in light engines such as scooter, motorcycle, and small aero plane engines. These engines are placed in front of the vehicle. Because air flow is without any disturbance .so cooling is very sufficient. Consists of fins which increase area of contact with the air. By increasing fins area, the air cooling will be more. By providing the fan, the mass of air flowing over the fins can be increased. This system is avoided the melting, seizing and overheating. Thank you.
A muffler (or silencer in British English) is a device for reducing the amount of noise emitted by a machine. On internal combustion engines, the engine exhaust blows out through the muffler. The internal combustion engine muffler or silencer was developed in parallel with the firearm. Mufflers are typically installed along the exhaust pipe as part of the exhaust system of an internal combustion engine (of a vehicle, or stationary) to reduce its exhaust noise. The exhaust gases must be discharged in to atmosphere with minimum restrictions in flow causes back pressure. Muffler is very important part of the vehicle.