Hi friends,
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.
Saturday, June 27, 2009
Tuesday, June 16, 2009
Cold working operation
Hi friends,
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.
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.
hot working operation
Hi folks,
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.
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
Hi friends,
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
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
Hi friends,
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
Hi folks,
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.
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
Hi folks,
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.
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.
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