**5.3 Improved strength**

Countergravity cast products have improved strength over green sand and ceramic mould specimens. The technique may be thus deployed in the production of high strength parts hitherto produced by forging. High Counter-Pressure Moulding, a proprietary variant, has been reported to exhibit the same strength characteristics as forging in alloy wheel production, at little more than the price of cast wheel (Alexander, 2002). Countergravity techniques are increasingly becoming the preferred choice for the production of alloy wheels because of the added advantage of design flexibility over forging processes. Furthermore, the Cosworth process, which achieves countergravity melt flow by means of an electromagnetic pump, has been successfully used for high strength structural components for air frames, gun cradles, and air tanker re-fuelling manifolds (Bray, 1989).

Griffiths *et al* (2007) observed that countergravity filling method produced higher values of the Weibull modulus than conventional gravity mould filling methods. This is a pointer to the reduced variability of strength achievable in the countergravity technique.
