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Subject: BMS7-373 Cu-Ni-Sn Material Specification (Cu-Be Replacement)
Purpose: 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.
Background: 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.
Results: 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.
Revisions are being made to BACB28AT, BACB28AU, BACB28AW, BACB28X and BACB28Y bushing standards to incorporate BMS7-373.
The material is proprietary and can be produced only by the facilities in the BMS7-373 QPL.
Shops supporting existing programs that wish to eliminate Cu-Be machining would need to review each drawing because the strength of BMS7-373 is less than that of Cu-Be.
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.
Disclaimer: The information provided in this website is intended to assist suppliers to The Boeing Company. Although every effort has been made to ensure its accuracy, we cannot warrant its accuracy for use in environmental compliance matters. You should check with your local, state or province and national regulating agencies if you have questions regarding the proper procedures or other matter related to compliance. Your Boeing Buyer can obtain additional information from spec custodians and technical experts. If applicable, Your Boeing Quality Assurance (PQA) Field Rep also has access to these contacts.
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