noname wrote:WhiteBlue wrote:Not any more. The advanced manufacturers of small axial turbines do the whole wheel out of one solid piece with 5-axis cutting.
You can have fully machined turbine wheel but, to my knowledge, the process is being used mainly to make TiAL wheels (or lower temp. applications). And ceramic materials are banned (except stuff like bearings).
Materials used for high temp wheels (they will, I think, work above 1000degC) exist only as casting. They are machined (contour, back side, etc.), but they are not made from the billet. However wax patterns are made on 5 axis CNCs.
Compressor wheels, on the other hand, are fully machined.
You can still machine High nickle alloys in a single piece system.
single piece wheels are generally done when turbines become to small to easily cast and a assemble its mostly for weight savings and manufactuability.
in smaller applications the centrifugal compressor is used to cut down rotating mass of multiple stages. As size goes up the inefficiencies start to climb and the weight savings advantage is lost. There is still the packaging benefit that might be worth more then we think in a cramped f1 car.