Subject: BMS7-373 Cu-Ni-Sn Material Specification (Cu-Be Replacement)
This page is designed to provide information on BMS 7-373 (Cu-Ni-Sn) which is a replacement for Cu-Be alloy called out in BMS7-353, AMS4533, AMS4535, and AMS4650 heat treated to the AT(TF00) condition.
Boeing has a commitment to producing environmentally preferred products. The company actively works to minimize or avoid the use of potentially hazardous materials, including Beryllium. Cu-Ni-Sn is a replacement for Cu-Be, which is hazardous, and for Al-Ni-Br where higher strength is required.
BMS7-373 comes in two classes, Class 100 for general applications up to 4.0" and Class 90 for swageable applications up to 3.0" (up to 4.0" in work). The primary use is in bushings and compression load wear applications. The use of Cu-Ni-Sn has also allowed the "grease allowable" to be increased over 50% ksi for oscillating joints, reducing weight. Cu-Ni-Sn will also allow static designed Al-Ni-Br joints to be smaller.
A higher-strength, cold-worked version of Cu-Ni-Sn, which will be a direct replacement for Cu-Be, is in work. The primary use of cold-worked Cu-Ni-Sn is in spherical bearings and highly loaded bushings