With high-speed steel-cored wheels the need for blotters is eliminated. Clamping is, therefore, steel on steel and not prone to the same brittle failure from stress risers. Nevertheless, there is the uncertainty on wheel contraction and its effect on clamping. One solution is to eliminate the flanges entirely. Landis (Waynesboro, Pennsylvania) developed a one-piece wheel hub where the entire wheel body and tapered mount are a single piece of steel with the vitrified CBN segments bonded onto the periphery [Pflager 1997].
FEA analysis was carried out on a range of steel-cored wheel shapes as shown in Figure 4.16 based on 500 mm diameter x 20 mm o. d. face running at 6,000 rpm (157 m/s).
4.6.4 The Single-Piece Wheel Hub
The straight one-piece hub was found to give the minimum level of bore expansion and is the design currently used in production. The “turbine” or parabolic profile minimizes outer diameter (o. d.) expansion but at the expense of some additional bore (i. d.) expansion. It is also considerably more expensive to machine. This one-piece design concept (Figure 4.17) has proved extremely successful in the crankshaft pin grinding and camshaft lobe grinding industries for speeds in the range of 60 to 120 m/s. It has eliminated the need for automatic balancers and allows fast change overtimes for lean manufacturing with minimal or no redress requirements.