Accession Number : ADA323801

Title :   Wire EDM Fatigue Study with Application to Multi-Lug Breech Mechanisms.

Descriptive Note : Final rept.,

Corporate Author : ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB

Personal Author(s) : Olmstead, V. J. ; Tauscher, S.

PDF Url : ADA323801

Report Date : JAN 1997

Pagination or Media Count : 35

Abstract : A fatigue study was conducted to evaluate wire electrical discharge machining (EDM) as a manufacturing method for the production of the intricate lug geometry on multi-lug breech mechanisms. The wire EDM process produces a thin surface layer of recast material that was found to have an adverse effect on specimen fatigue life. Removal of the recast layer is recommended on highly stressed critical components. Unidirectional bending fatigue tests were performed utilizing notched rectangular test specimens made from ASTM A723 steel material. The fatigue tests compared wire EDM prepared surfaces to those produced by the conventional drilling and honing process. The effects of multiple EDM passes and post-processing techniques such as bead blast cleaning, shot peening, and mechanical overloading were investigated. The recast layer was found to have a significant detrimental effect on specimen fatigue lives. Fatigue life reductions of 20 to 40 percent were observed. The deleterious effect on fatigue increases as the applied stress decreases. The post-processing techniques improved lives but they were generally inferior to those that were conventionally machined and treated with the same process. In limited testing, the combination of glass bead cleaning and mechanical overloading provided 'significant' improvement in life compared to either process applied individually.

Descriptors :   *BREECH MECHANISMS, *FATIGUE TESTS(MECHANICS), TEST AND EVALUATION, STRESSES, MANUFACTURING, PRODUCTION, FATIGUE LIFE, MACHINING, LAYERS, PROCESSING, WIRE, TEST METHODS, BENDING, REDUCTION, SURFACES, RECTANGULAR BODIES, ADVERSE CONDITIONS, ELECTRIC DISCHARGES, GEOMETRY, THINNESS, CRITICALITY(GENERAL), DRILLING, UNIDIRECTIONAL, SHOT PEENING, LUGS.

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE