DESIGN CONSIDERATION ASSOCIATED WITH ADOPTION OF NEW SPRING MATERIALS.

The paper discusses the possibilities of application of two new experimental alloys, namely, CA 725 (CuNi9Sn2) and IN-629 (Cu-Ni15Zn28Mn13) for the manufacture of springs. It is shown that CA 725 is rapidly replacing phosphorubronze in certain applications in the United States because its use reduces costs. It has good atmospheric tarnish resistance compared with brass an phosphorus bronze and therefore does not need protective nickel, silver or gold plating to preserve its surface. IN-629 offers savings in cost over beryllium and is assessed by several companies at its replacement. IN 629 develops high strength by virtue of a very fine grain size produced in the course of manufacture and by cold rolling. Unlike beryllium copper, it does not have a high material cost, nor does it require expensive heat treatment of finished components to develop high strength. The low electrical conductivity of IN 629 is not a handicap to its use in low-current applications.