Mechanical tools

. advantage and disadvantage of hot working metal . advantage and disadvantage of cold working of metal Working on metals This involves the manipulation of metals /materials when in the solid state Examples of working are forming, rolling, forging etc. Working processess can be classified Hot working Cold working  Hot working  Hot working is done at a suitable high temparature so that any damage to the grains is repaired. The temparature required varies from metal to metal. Examples of hot working Forging, rolling, extrusion et Advantage of hot working -hot working is relatively a low cost process -refinement of grain from cast structure is possible. -the scale givea some protection against corrosion during storage. After the process also the product will be in the fully annealed condition, suitable for further cold working. Disadvantage of hot working -poor surface finish is likely -dimensional inaccuracy is possible due to shrinkage on cooling -geometrical accuracy is possib...

. meaning of friction . advantage and disadvantage of friction . different types of friction . methods of reducing friction Friction is the force that offers resistance to relative motion between surfaces in contact. Friction opposes motion irrespective of the direction. When a book is made to slide on the surface of a table from left to right, the force of friction acts on the lower surface of the book towards the left. Advantages Friction plays an important role in our life. Walking would be impossible without friction between the foot and the ground. Unless there is friction, it would not be possible to lean a ladder against a wall, turn the pages of a hook, tie shoelaces etc. Because of friction -rolling motion is possible -sliding motion is possible -gripping effect is possible Disadvantage -reduction in efficiency of machines -wear and tear of all sliding surfaces in contact -unwanted heat generation Types of friction Different types of friction are as follows -Limiting friction ...