FEM supported semi-solid high pressure die casting process optimization based on rheological properties by isothermal compression tests at thixo temperatures extracted

Rheological properties of aluminum are among others required in FEM supported calculations of thixo-forming processes. In the present paper, an analytical-experimental method is introduced to acquire such properties as a function of temperature and flow velocity. This method is based on isothermal compressive tests' results evaluation at various temperatures. The determined rheological properties are used to optimize thixo-forming process parameters and ensure die filling during high pressure semi-solid casting, without air entrapments. Considering the developed temperature field, hot spots can be avoided by employing cooling systems at proper positions. An application example is demonstrated in the case of high pressure die casting of an aluminum car wheel

Coated tool wear behaviour in up and down milling at various chip lengths explained by the cutting edge impact loads

Milling operations for manufacturing dies and molds are commonly linked to complicated chip geometry and contact conditions between tool and workpiece. These parameters render the optimisation of the cutting conditions and the description of the tool wear difficult. In the described experiments, coated cemented carbide inserts fixed on a milling cutter were applied in down and up milling for monitoring the wear behaviour at various cutting edge entry conditions, which result in various chip lengths. The corresponding developed strain rates cause different film-substrate deformations and resulting loads. These phenomena were investigated with the aid of a new impact tester with adjustable impact force characteristics. The effective tool life up to a certain flank wear land width versus the cutting edge entry duration was explained and analytically described

Insights into building a digital twin of closed-cell aluminum foam during impact loading: Microstructural, experimental and finite element investigations

The mechanical behavior of metal foams under impact loading depends on multiple and complex parameters like impact velocity, strain-rate, local plastic deformation, oscillating and micro-inertial effects, etc. The prediction of the behavior of metal foams that are subject to impact loads is still challenging and engineering application of these materials typically requires time-consuming experimental tests. Numerical models based on the finite element method (FEM) can contribute to minimizing the experimentation effort. Realistic FEM models were built that account both for the macro- and micro-scopic characteristics of the porous material, explain the acting mechanisms that take place during impact, and study the yield properties as well as the energy absorption during the impact of closed-cell aluminum foams. The simulation results are compared with the ones derived from respective experimental uniaxial tests. Two different modeling approaches were applied thus creating two models. The first model relies on a cell-based method where the initial geometry of the foam was generated based on the Voronoi tessellation algorithm and the second one relies on the isotropic, strain-hardening, and continuum-based model developed by Deshpande-Fleck. The outcome of the investigation sheds light on the metal foam behavior under impact by explaining macro- and micro-structural phenomena that develop during impact

High performance up and down milling stainless steel considering coated tools' dynamic loads

Coated cemented carbide inserts were applied in up- and down-milling stainless steel for monitoring the tool wear at repetitive cutting loads of various magnitudes and durations. Via impact tests with adjustable force signal characteristics, the applied loads can simulate the developed ones in milling when the cutting edge penetrates the workpiece. The attained tool life of coated inserts was associated with the developed maximum strain and its rate in the film during milling. The latter factors were correlated to the strain and strain rate dependent coating fatigue endurance. Based on these issues, the tool life was explained in various milling kinematics