Monday, June 21, 2010

QC on the Crankcase Girdle

The sample casting for the crankcase lower section just came in. This part contains the crankshaft lower bearing caps, oil pump/filter and drive system, and the transmission and clutch. Although it looks visually more complicated than the crankcase top, it is a simpler piece to cast in that there is only one internal passages requiring a buried core, namely for the oil pump pressure area.

The placement of this core is less critical than those for the cylinder bores because of the lower pressure and thermal stresses this area experiences. This core forms the pump inlet and outlet ports, high pressure chamber, pressure relief valve port, and oil filter mounting boss details all in one piece. One of the benefits of the casting process is that part complexity is not penalized as it is with billet parts.

The QC process used on this part will be the same as for the crankcase top:

  • scan

  • overlay to CAD to verify fidelity to the CAD model.

This sample part was dimensionally excellent. There are a couple of areas I may modify after going through the part's CNC programming process. I'll know more as the part moves through the various machining stages.

That's all for now.