Sweep moldings are employed for molding parts whose shape is that of a surface of revolution. In the preliminary process, a base 1 and spindle 2 is well placed in the foundry floor. The sand is filled in and rammed until the excavation forms approximately the shape and size of the required casting. A sweep holder 5 is then placed in the spindle land the sweep 6 is attached by bolts and nuts. The surface of the mold is produced by the profile of the sweep as it is rotated about the spindle. After sweeping, the spindle is removed and the mold patched at the center. The gate is then cut and the mold is ready for pouring.
CHERNOBYL NUCLEAR DISASTER (NUCLEAR POLLUTION) : In April 26,1986, the melt down of the Chernobyl nuclear reactor , in Russia, has leaked out the radioactive rays and radioactive materials. Effects : 1. In this Pollution nearly 2000 persons have been killed by the accident. 2. People suffered due to the illness such as, degeneration of the cells, severe bleeding, anemia, skin cancer. 3. Animals, Plants are also affected by nuclear radiation. MINAMATA EPIDEMIC (1953) : MARINE POLLUTION ( CASE STUDY ) Minamata is a small coastal village in Japan. The Chisso Chemical Company , which produces vinyl polymer plastics used organomercurial compound. The industry released its effluent into Minamata sea. The effluent containing mercury ions is converted into methyl mercury, which is highly toxic. The marine organisms like phytoplankton and zoo-planktons easily absorb the toxic methyl mercury compound. These organisms are consumed by small fishes and these are in ...
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