. During the casting or forging stage, the purpose should be to observe closer weight tolerances with improved balance weight.PM is the better choice in the material to be used for connecting rods, as it ensures closer weight tolerances and it is the best as far as the weight reduction objectives are concerned. This results in reduced machining time as well. This also eliminates, in most of the cases the weight balancing operation.
While “squeeze casting” can give the advantages of both, forging and casting processes, below is a table giving the properties and application of various types of Cast Irons.
The machining procedure for the manufacture of connecting rods usually is based on the following pattern.
• Rough grinding of faces
Any grinder or a grinding machine, for removing the excess material acumulated during forging or casting operation, can do this operation.
• Machining of piston pin bore.
The piston pin bore is taken as the reference hole for the connecting rod. Therefore, the final machining of the piston pin bore is required. Special honing machines can further hone the bore.
• Milling and broaching of faces at the end of crank bore
This is an important operation, as the crank bore end has to match with the connecting rod end. Specialized milling and broaching machines are used for this purpose.