In this application, the grinding of a crankshaft journal was checked for unfavorable stresses due to overheating during grinding, also known as grinding burn.

MBN is quantitative, repeatable, non-destructive, and it is easily automated, thus removing operator influence as a variable.

Modern industry has many requirements like cost efficiency, durability, lightness of manufactured parts and eco-friendliness to name a few. With these requirements in mind it’s crucial to have deep understanding of the manufacturing process and how it affects the finished part. Residual stress is one physical property that is becoming more crucial as the requirements and quality of manufacturing process grow.

Cold working causes plastic deformation that creates residual stresses. The degree and sign of the residual stress depend on degree and type of the working process. Shot peening is a cold working process in which the surface of a component is peened with small spherical balls called shots. The process induces plastic deformation on the surface, relieves surface tensile stresses and introduces beneficial compressive residual stresses. Shot peening is a similar process with surface rolling, both deform the surface plastically to develop a compressive residual stress depth profile.

Residual stresses are spontaneously in equilibrium as tensile residual stresses (detrimental) and compressive residual stresses (beneficial). For example, a surface formed in tensile stresses will comprise compressive residual stresses, and a surface formed in compressive stresses will contain tensile residual stresses.

There are many methods to measure residual stresses. The methods are commonly grouped as non-destructive, semi-destructive and destructive or diffraction based, strain relaxation based and other methods. However, they all have the same common point: being indirect. There is no direct method available to measure stresses: they are calculated or derived from a measured quantity such as elastic strain or displacement.

Residual stress measurement is one essential way to find out if the component can withstand the demanding load and stress conditions in its service life.

Thermal and mechanical treatments are available to relieve the residual stresses.

Distortion is the unexpected, uneven change in size or shape caused by dissimilarities in manufacturing and heat treatment processes. Distortion is affected by material properties, part geometry, the size of the component and the most importantly the residual stress state of the component.

Residual stresses are induced during the machining due to mechanical, thermal or chemical factors. They may lead to lower fatigue life hence they should be analyzed and controlled.