Gas Metal Arc Welding

ABSTRACT:

Gas Metal Arc Welding (GMAW) is an arc welding process that joins metals together by heating them with an electric arc that is established between a consumable electrode (wire) and the work-piece. Shielding of the arc and the molten weld pool is often obtained by using inert gases such as argon and helium, and this is why GMAW is also called the metal–inert gas (MIG) welding process. Since non-inert gases, particularly CO2, are also used, GMAW seems a more appropriate name.


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Resource Conservation

ABSTRACT:

Resources are the things from the environment which are useful to human beings. Natural resources are resources we get from nature (example: fossil fuels, water, minerals from soil). The term conservation came into use in the late 19th century and referred to the management, mainly for economic reasons, of valuable natural resources. But conservation of natural resources is now usually embraced in the broader conception of conserving the earth itself by protecting its capacity for self-renewal. Particularly complex are the problems of non-renewable resources such as oil and coal and other minerals in great demand. The growing population, rapid industrialisation and urbanisation have created heavy demand on all these materials. Conservation of resources not only means the protection but also the judicious use of the resources so that they don't get exhausted. Management of the human use of natural resources to provide the maximum benefit to current generations while maintaining capacity to meet the needs of future generations is called Conservation of resources.

Essentiality of resources to satisfy the needs of humans as living organisms is mentioned and so is exhaustibility of most of them. Conservation is the main point of the answer to this resource crisis. Present state of this problem is very alarming and will go fully out of control if we don’t act quickly and spontaneously. This is one of the main problems of civilisation at present and this problem cannot be managed without the help of everyone. And to get everyone’s help at first everyone should be known about the matter. Awareness should be generated and spread among the people. And that’s why this topic has been chosen to be discussed.

resource conservation doc

Gas Welding

ABSTRACT:

Although the oxyacetylene process has been introduced long time ago it is still applied for its flexibility and mobility. Equipment for oxyacetylene welding consists of just a few elements, the energy necessary for welding can be transported in cylinders.Process energy is obtained from the exothermal chemical reaction between oxygen and a combustible gas, Figure 1.2. Suitable combustible gases are C2H2, lighting gas, H2, C3H8 and natural gas; here C3H8 has the highest calorific value. The highest flame intensity from point of view of calorific value and flame propagation speed is, however, obtained with C2H2. C2H2 is produced in acetylene gas generators by the exothermal transformation of calcium carbide with water, Carbide is obtained from the reaction of lime and car- bon in the arc furnace.C2H2 tends to decompose already at a pressure of 0.2 MPa. Nonetheless, commercial quantities can be stored when C2H2 is dis- solved in acetone.

Acetone disintegrates at a pressure of more than 1.8 MPa, i.e., with a filling pressure of 1.5 MPa the storage of 6m3 of C2H2 is possible in a standard cylinder (40 l). For gas ex- change (storage and drawing of quantities up to 700 l/h) a larger surface is necessary, therefore the gas cylinders are filled with a porous mass (diatomite). Gas consumption during welding can be observed from the weight reduction of the gas cylinder.

gas welding pdf

Maglev Levitation Trains

ABSTRACT:

The report titled ‘MAGLEV TRAINS’ accomplishes a research on the developing discipline of magnetic levitation and its application to transportation through trains. It provides detailed information about the evolution of maglev science, its progression and improvisation till date. High-speed magnetically levitated ground transportation (maglev) is a new surface mode of transportation, in which vehicles glide above their guideways, suspended, guided, and propelled by magnetic forces. This report tries to explain the complexities involved in this technology in a simple but precise manner, so that all the methods implemented in it are understood by the reader at prima facie. This report, tries to compare the conventional modes of transport with maglev trains in various aspects such as safety, durability, speed, comfort and so on. Thus, providing the advantages and disadvantages of the trains. Further, this report helps us to learn about the various cities around the world, where maglev trains currently run and also provides an overview of the proposals for such trains, which are being considered as a promising investment globally. Consecutively, it deals with the accidents that have occurred at places where maglev trains have been implemented and the reasons that triggered them. This data has been included so that such incidents may be avoided in the future and in order that certain necessary modifications are made to improve the safety measures of these trains. Capable of travelling at speeds of 250 to 300 miles-per-hour or higher, maglev would offer an attractive and convenient alternative for travellers between large urban areas for trips of up to 600 miles. It would also help relieve current and projected air and highway congestion by substituting for short-haul air trips, thus releasing capacity for more efficient long-haul service at crowded airports, and by diverting a portion of highway trips. Finally, our report gives a peek into the future expansions of maglev trains and thus undoubtedly assures its readers that maglev trains are no longer a science fiction, and are in fact the future of world transportation.


maglev levitation trains ppt