A new technique for the determination of superficial residual stresses associated with machining and other manufacturing processes

Manufacturing processes induce residual stresses in components. The manufacturing operations path that a component has to undertake is critical in the formation of these residual stresses, as a change in processing order can change the residual stress profile of the component. There are many techniques available to both industry and researchers to measure these residual stresses. However, some of these techniques require either expensive equipment, highly trained operators or both. Other techniques require that holes be drilled into the component thus rendering the component useless. This paper introduces a new technique to measure superficial residual stresses, through the use of simple, easily available equipment. The technique involves the measurement of the change in spacing of pairs of hardness indents, which occurs upon relief of residual stress. The motivation for this paper was the exploitation of the potential advantages that high speed machining (HSM) offers to industry with regard to induced residual stresses. The new technique was developed by the authors to allow for confirmation of previously published results pertaining to the effects of HSM on such stresses and subsequently product life.