2 results
Now showing1 - 2 of 2
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Temperature field due to a moving heat source in machining orthotropic composites with arbitrary fiber orientationMilling of fiber reinforced plastics (FRP) is challenging with respect to surface integrity and tool wear due to high process temperatures. The maximum temperatures occurring in the workpiece determine the extent of the matrix decomposition area. Improving the workpiece quality therefore requires an understanding of its internal temperature distribution during milling. However, steep temperature gradients and high mechanical stress make measurements of temperature fields in the cutting zone difficult. In addition, thermal properties change depending on the fiber orientation in the case of orthotropic FRP. In this paper, an existing model describing the temperature field for isotropic materials is extended to unidirectional, orthotropic FRP. Here, the thermal impact of an end mill upon the machined surface is represented by a strip-shaped heat source which moves with the feed velocity along a semi-infinite space. Starting with the temperature field of an instantaneous point source, multiple integration steps and a coordinate transformation lead to the temperature field of the moving strip source for orthotropic materials with arbitrary fiber orientation. Using this analytical approach, two-dimensional temperature fields within the workpiece can be calculated for various feed velocities, heat source widths and fiber orientation angles. A cross verification of the analytical solution is successfully carried out by comparing it to a numerical simulation. Furthermore, temperature measurements during end milling of carbon fiber reinforced plastics using thermocouples confirm these results for different fiber orientations. The derived model can be applied to a variety of heat flow problems relevant for orthotropic materials, e.g. other machining technologies.Publicationtype: Conference PaperScopus© Citations 3 266 207 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Helical milling of bore holes in Ti6Al4V parts produced by selective laser melting with simultaneous support structure removal(Elsevier, 2018-12-13); ; ; ; Selective Laser Melting (SLM) is a powder bed based Additive Manufacturing (AM) process that is currently being established in the series production of Ti6Al4V components in the aviation industry. One advantage is the significantly lower Buy-to-Fly ratio. However, subsequent machining is necessary in order to remove support structures of the SLM process and to fulfill quality requirements. Experimental results on support structure removal and simultaneous finishing of holes by helical milling are presented. Engagement conditions in helical milling are strongly influenced by the support structure. Material removal rates in both peripheral and axial direction are calculated and agree well with the variation of measured forces in these directions. In addition, the surface roughness of the machined holes is affected by the support structure design and may change along the hole perimeter. The findings indicate how support structures should be designed in order to obtain high quality bore holes in one machining step.Publicationtype: Journal ArticleScopus© Citations 5 308 268