Experimental study of the connection between process parameters, thermo-mechanical loads and surface integrity in machining Inconel 718

Procedia CIRP, vol. 87, pp. 59–64

Abstract

The machining process has a major influence on the microstructure and the residual stresses of the manufactured surface and it’s final functionality. This functionality of surface integrity is of particular interest in safety critical aero engine parts made of temperature resistant super alloys such as nickel-chromium-based alloys. Besides the high tool wear, the machining of such materials is in particular challenging with regard to process induced microstructure alterations and the formation of low toughness and high hardness white layers. The current publication shows an experimental study and affiliated methodology in order to examine the influence of the process state conditions on the surface integrity, with regard to localized temperatures and forces causing white layer as well as residual stresses. On the experimental side a tailor made orthogonal milling setup was used in order to evaluate the transient temperature fields occurring in the workpiece together with the fluctuating process forces acting on its surface. This setup included a synchronized dynamometer, a thermal camera as well as a ratio pyrometer. The cutting forces and cutting normal forces under known engagement conditions were calculated from the transformed Cartesian dynamometer measurements and the measured cutter rotation angle. An evaluation of the surface integrity alteration was finally carried out analyzing the surface microstructure by light microscopy as well as residual stress measurements by X-ray diffraction.

Authors 5

1. Thorsten Augspurger corresponding Aachen Laboratory for Machine Tools and Production Engineering (WZL)

   RWTH Aachen University

   Affiliation as printed

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus Boulevard 30, 52074 Aachen, Germany

2. Markus Meurer Aachen Laboratory for Machine Tools and Production Engineering (WZL)

   RWTH Aachen University

   Affiliation as printed

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus Boulevard 30, 52074 Aachen, Germany

3. Hui Liu Aachen Laboratory for Machine Tools and Production Engineering (WZL)

   RWTH Aachen University

   Affiliation as printed

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus Boulevard 30, 52074 Aachen, Germany

4. Patrick Mattfeld Aachen Laboratory for Machine Tools and Production Engineering (WZL)

   RWTH Aachen University

   Affiliation as printed

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus Boulevard 30, 52074 Aachen, Germany

5. Thomas Bergs Aachen Laboratory for Machine Tools and Production Engineering (WZL)

   RWTH Aachen University

   Affiliation as printed

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus Boulevard 30, 52074 Aachen, Germany