Originally Posted by
NikoRacing
Saying that the parts are extracted is not correct. The parts comes from extracted material (a bar of aluminum) but then you have to CNC the part as you want to obtain a piece. This is the same process as the one used to obtain a rod or a piston for an engine. Parts are smooth because of the quality of the CNC process and the fact that part are brightened with other products that put the cnc marks away.
Yes they are. Take a look at one side of a bulk head for the MRX-5. One side you will see milling marks, the other side you will see a grain that goes from one end to the other. The grain is formed from the saw cutting off the extrusion. After being cut off of the extrusion one side was milled flat to provide "zero". The part has all the holes and windows in it, it was extruded 90% complete. The only thing left is to drill and tap some holes for screws and hinge pins.
Rods are forged from billet. Pistons are either machined from billet or low pressure cast.