Mechanical Engineering



Written by V R Sunday, 23 May 2010 20:03

Coining is the process of conforming a metal part in a die and pressing it using a punch in order to get an impression or configuration on the surface of the metal.The configuration required on the surface of product are suitably made in the die as well as in the punch.after placing the metal in die , a heavy pressure is applied by the punch.The metal gets squeezed and flows plastically to the required configuration between the die and punch.




Written by V R Sunday, 23 May 2010 19:54

Welding is the process of joining two metals by the application of heat.Heat for welding process can be obtained from many sources such as smith's hearth for forge welding,electric current for resistance welding,gas flames for gas welding,chemical reaction for thermit welding and electric arc for arc welding etc.

Welding is done with the help of a welding machine.the welding machine raises the temperature of the required portions of the work pieces so that it can fuse them.depending upon the type of heat production welding processes are classified as (i) electrical resistance welding(ii)arc welding(iii)gas welding(iv)thermit welding.



Written by V R Sunday, 23 May 2010 19:47

Lapping is another abrading process performed to produce a smooth surface,or to provide accurate fit of contacting surfaces.It is performed manually or by machine by charging a lap made of a material softer than the workpiece surface.Charging a lap means to embed the abrasive grains into it surface.Very thin layers of metal are removed in lapping and hence it is used for removing minor defects in the previous operation like tool marks,surface cracks,surface roughness etc.




Written by V R Sunday, 23 May 2010 19:41

Honing is an abrading process in which stock is removed from metallic or non-metallic surfaces by bonded abrasive sticks.In honing a surface ,the stick is pressed against the surface with more or less constant pressure and the stick is then slide to and fro at a slow speed.The amount of material removed is generally quite small and the process is essentially one for eliminating local irregularities of the surfaces rather than shaping the surface as a whole.For honing cylindrical holes the sticks are arranged in a circle.these sticks are expanded outwardly after being inserted in the hole and then is rotated at the same time reciprocated up and down.

The honing operation may be done manually or by machine.Even though honing operation can be done on lathe and drilling machines,special purpose honing machines are available in two types,horizontal and vertical honing machine.A honing machine rotates and reciprocates the hone inside the hole being finished.

Grinding machine.


Written by V R Sunday, 23 May 2010 19:30

Grinding is a process of metal removal in which the cutting tool used is an abrasive wheel.Grinding is mainly used for the following purposes:

  • To remove small amount of metal from the work piece to bring its dimensions within very close tolerance of the size desired.
  • To obtain better finish on the surface.
  • To machine hard surfaces which are otherwise difficult to be machined by other means.
  • To sharpen the cutting tools.

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