manufacturing of engine parts

Replies

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  mechky

  cylinder head - casting
  cylinder block - casting
  piston - forging nowadays, earlier it was cast
  connecting rod - forging
  poppet valves - forging
  piston rings - casting, forging
  cylinder liners - casting
  camshafts - casting, forging, machining
  
  Casting is preferred when there is complex design, large & heavy parts, high production rate etc. Forging is preferred when good mechanical properties are required. There are variety of methods to produce a part and each has its own advantages & disadvantages. There are many factors to be considered before selecting a manufacturing process. So, in case of an IC engine if you look & observe the complex shape of cylinder head & cylinder block then you can understand why they are casted.
• 

  zaveri

  what about the crankshaft ? i have read in many books that it is forged, even though its complex design calls for the casting process. but its forging is understandable when we consider its functions of transmitting torque.
  
  also, what about the manifolds ? are they made by the tube drawing processes ?
• 

  mechky

  zaveri

  what about the crankshaft ? i have read in many books that it is forged, even though its complex design calls for the casting process. but its forging is understandable when we consider its functions of transmitting torque.
  
  also, what about the manifolds ? are they made by the tube drawing processes ?

  Yes, I missed crankshaft. There are three types of manufacturing techniques used to make crankshafts- casting, forging and machining from solid billet.
  Strength of casted crankshafts will be the lowest but manufacturing is relatively easy. Cast steel crankshafts are perfectly suitable in the right application. Forged steel crankshafts have tensile strength almost similar to cast steel crankshafts but have much better elongation properties. Forged alloy steel crankshafts have higher tensile strength. Machined crankshafts have further high tensile strength.
  One of the weak point in a crankshaft is where the rod journal meets the web. The force exerted on the rod journal by the rod causes the web on either side of the journal to flex in and out. In a forged crank, the grain of the steel is flowed and condensed making it stronger and tougher. In CNC billet crank, the grain of the metal will run parallel to the centreline of the shaft. If the grain converges at a stress point there is greater possibility of crack to develop. However, with special alloys in billet material a stronger camshaft can be manufactured.
  
  Intake & exhaust manifolds, as per my knowledge are made by casting processes.
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  zaveri

  mechky

  Forged steel crankshafts have tensile strength almost similar to cast steel crankshafts but have much better elongation properties. Forged alloy steel crankshafts have higher tensile strength. Machined crankshafts have further high tensile strength.

  are crankshafts subjected to tensile loads ? as far as i know they are subjected to torsion and bending moment , then why do we need tensile strength ?
• 

  zaveri

  mechky

  Intake & exhaust manifolds, as per my knowledge are made by casting processes.

  if they are made of casting process then what kind of patterns do they use ? skeleton pattern ?
• 

  mechky

  zaveri

  are crankshafts subjected to tensile loads ? as far as i know they are subjected to torsion and bending moment , then why do we need tensile strength ?

  Correct, it was just to have a strength comparison between different manufacturing processes.
• 

  mechky

  zaveri

  if they are made of casting process then what kind of patterns do they use ? skeleton pattern ?

  Could be, I am not aware of that.