Improved Buttress Thread Machining for the Excalibur and Extended Range Guided Munitions
Abstract
Raytheon Missile Systems (Raytheon) of Tucson, Arizona, manufacturer of the Excalibur and Extended Range Guided Munitions (ERGM) have consistently received critical components containing Class III, 7 degree/45 degree buttress threads out-of-tolerance from their suppliers. These out-of-tolerance conditions have caused failures of the components at the buttress thread joints. The Rockwell hardness of the 4340 steel (Rc53) being used for the components is a major contributor to the out-of-tolerance condition. The National Center for Defense Manufacturing and Machining (NCDMM) was requested to evaluate and optimize the machining of these Class III buttress threads to eliminate the failures. After reviewing the supplied material and current processes, the NCDMM developed a plan to optimize cutting of both the internal and external threads using advanced technologies and methodologies. After completing numerous detailed designs of experiments (DOE), the NCDMM was successful in consistently machining the internal and external buttress threads in the 4340 material. These new machining parameters ensure that the threads meet the required tolerances specified in ANSI B1.9 - 1992.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 21, 2006
- Accession Number
- ADA482114
Entities
Organizations
- National Center for Defense Manufacturing and Machining