Stability starts with the purchase specification

Gerald Gould

doi:10.1117/12.22874

1 November 1990 Stability starts with the purchase specification

Gerald Gould

Proceedings Volume 1335, Dimensional Stability; (1990) https://doi.org/10.1117/12.22874
Event: 34th Annual International Technical Symposium on Optical and Optoelectronic Applied Science and Engineering, 1990, San Diego, CA, United States

Abstract

Comprehensive Purchase Specification(s) must not merely define a generic type of material by chemistry and mechanical properties. It must be capable of specifying the method of material formation (i. e. rolled cast forged vacuum hot pressed etc. ) it''s grain size preferred orientation homogeneity etc and the method of material removal to minimize surface damage and/or work hardening. Starting out with heavily stressed material will in many instances negate the possibility of fabricating components which can be subsequently processed and heat treated to eliminate the residual stresses which cause components to change dimensionally and/or creep or experience premature micro-yielding - the anisotropy of work hardening Bauschinger Effect. . MATERIAL AND FORM SELECTION In order to produce parts or precision assemblies with maximum stability one must recognize the various forms that are available and the selection of alloys to choose from. The next step may be selecting a form with the best homogeneity or a form which will permit the subsequent processing to a condition of useable stability (minimum residual stress). Another vexing problem is the fabricating of parts from bar or plate for prototypes and the subsequent purchase of cast or powder compacted parts for production. Two very diverse material conditions. A brief familiarization (See Figure 1 and 2) with the forms available from a partial list is a starting point in the ultimate selection of form alloy condition and subsequent

Citation Download Citation

Gerald Gould "Stability starts with the purchase specification", Proc. SPIE 1335, Dimensional Stability, (1 November 1990); https://doi.org/10.1117/12.22874

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