Schleifen von WC-Co-Hartmetallen*/Grinding of Cemented Carbides (WC-Co)

2016 ◽  
Vol 106 (06) ◽  
pp. 374-379
Author(s):  
C. Wirtz ◽  
F. Vits ◽  
P. Mattfeld ◽  
F. Prof. Klocke
Keyword(s):  
Brittle Material ◽  
Brittle Materials ◽  
Material Behavior ◽  
Ductile Material ◽  
Cemented Carbides ◽  
Multi Phase

Beim Schleifen mehrphasiger Werkstoffe mit sprödhartem Charakter, beispielsweise Hartmetall, wurde ein Übergang von sprödhartem zu duktilem Werkstoffverhalten nachgewiesen. Der Fachartikel stellt eine neu entwickelte Methodik zur systematischen Analyse des Zerspanverhaltens – im Speziellen den Übergang von vorwiegend duktilem zu überwiegend sprödhartem Zerspanverhalten – für Hartmetalle vor.   In grinding of multi-phase, brittle materials, e. g. cemented carbides, a transition from predominantly brittle to predominantly ductile material behavior has been proven scientifically. This paper presents a newly developed methodology to analyze the material behavior of cemented carbides, in particular the transition from ductile to brittle material behavior.

A Discussion on Material Removal Mechanisms in Grinding of Cemented Carbides

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Christian Wirtz ◽  
Sebastian Mueller ◽  
Patrick Mattfeld ◽  
Fritz Klocke
Keyword(s):  
Material Removal ◽  
Brittle Materials ◽  
Material Behavior ◽  
Cemented Carbides ◽  
Surface Zone ◽  
Scanning Electron Micrographs ◽  
Material Removal Mechanisms ◽  
Ductile Materials ◽  
Removal Mechanisms ◽  
The Impact

In the literature, cemented carbides are described as hard and brittle materials. The material removal mechanisms in grinding of brittle materials, such as cemented carbides, significantly differ from the material removal mechanisms of ductile materials [1–3]. The material removal mechanisms in grinding of ductile materials are comparatively well investigated in comparison to the material removal mechanisms in grinding of brittle materials. In the existing literature, it has been shown that the material removal mechanisms in grinding of cemented carbides can be ductile or brittle. The present material removal mechanisms are dependent on the thermomechanical stress collective, which acts on the surface zone of the cemented carbides. In this paper, the material removal mechanisms in grinding of cemented carbides are discussed fundamentally. In order to analyze the occurring material removal mechanisms in grinding of cemented carbides, single grain cutting tests were carried out. Subsequent to the tests, the surface zone of the cemented carbide has been analyzed in detail. Therefore, scanning electron micrographs have been made to analyze the workpiece surface to identify the transition from predominantly ductile to predominantly brittle material behavior. Furthermore, focused ion beam (FIB) preparation, which has minimum invasive influence on the subsurface, was applied in order to get an insight into the surface zone. The FIB lamellae have been analyzed with transmission electron microscopy (TEM) to get a better understanding of the impact of material removal mechanisms on the surface zone. The drawn conclusions contribute to an improved process understanding in grinding of cemented carbides.

scholarly journals Simulation of the ductile machining mode of silicon

2021 ◽  
Author(s):  
Hagen Klippel ◽  
Stefan Süssmaier ◽  
Matthias Röthlin ◽  
Mohamadreza Afrasiabi ◽  
Uygar Pala ◽  
...  
Keyword(s):  
Brittle Material ◽  
Material Removal ◽  
Machining Process ◽  
Ductile Material ◽  
Diamond Wire ◽  
Ductile Machining ◽  
Mesh Free ◽  
Diamond Wire Sawing ◽  
Material Removal Mode ◽  
Brittle Material Removal

AbstractDiamond wire sawing has been developed to reduce the cutting loss when cutting silicon wafers from ingots. The surface of silicon solar cells must be flawless in order to achieve the highest possible efficiency. However, the surface is damaged during sawing. The extent of the damage depends primarily on the material removal mode. Under certain conditions, the generally brittle material can be machined in ductile mode, whereby considerably fewer cracks occur in the surface than with brittle material removal. In the presented paper, a numerical model is developed in order to support the optimisation of the machining process regarding the transition between ductile and brittle material removal. The simulations are performed with an GPU-accelerated in-house developed code using mesh-free methods which easily handle large deformations while classic methods like FEM would require intensive remeshing. The Johnson-Cook flow stress model is implemented and used to evaluate the applicability of a model for ductile material behaviour in the transition zone between ductile and brittle removal mode. The simulation results are compared with results obtained from single grain scratch experiments using a real, non-idealised grain geometry as present in the diamond wire sawing process.

scholarly journals Дестабилизация внедрения высокоскоростной струи в хрупких материалах

2019 ◽  
Vol 89 (5) ◽  
pp. 685
Author(s):  
Б.В. Румянцев
Keyword(s):  
Brittle Material ◽  
High Speed ◽  
Bending Strength ◽  
Brittle Materials ◽  
Absorption Efficiency ◽  
Hydrodynamic Approximation ◽  
Metal Jet

AbstractThe results of penetration of a high-speed metal jet (with a velocity of 3–7 km/s) into brittle materials (ceramics and glass) have been analyzed. The data on jet destabilization as a result of the response of the brittle material to the high-speed penetration are presented. The generalized dependence of the high-speed jet absorption efficiency on the bending strength of the brittle material has been constructed in the hydrodynamic approximation.

Ductile-Regime Machining for Fast Tool Servo Diamond Turning of Micro-Structured Surfaces on Brittle Materials

2012 ◽  
Vol 500 ◽  
pp. 333-338 ◽  
Author(s):  
De Ping Yu ◽  
Yoke San Wong ◽  
Geok Soon Hong
Keyword(s):  
Experimental Investigation ◽  
Brittle Material ◽  
Brittle Materials ◽  
Diamond Turning ◽  
Fast Tool Servo ◽  
Entire Surface ◽  
Structured Surfaces ◽  
Simulation Based ◽  
Ductile Regime Machining ◽  
Machining Characteristics

Micro-structured surfaces on brittle materials, e.g. ceramic and glass, are gaining increasing application in a range of areas. In this paper, fast tool servo (FTS) diamond turning has been applied to machine micro-structured surfaces on brittle materials and the machined surfaces has been observed to study its machining mechanism. A machining model is presented to enable ductile-regime machining of the brittle material. Based on the model, machining characteristics can be predicted for given cutting conditions. Experimental investigation on machining of a micro-structured surface verified that ductile-regime machining can be ensured on the entire surface through path planning simulation based on the machining model.

Small Scale Yielding at a Crack Normal to the Interface Between an Elastic and a Yielding Material

1991 ◽  
Vol 239 ◽  
Author(s):  
Ming Y. He ◽  
R. M. McMeeking ◽  
Ning T. Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Brittle Material ◽  
Crack Tip ◽  
Asymptotic Solutions ◽  
Ductile Material ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Element Analysis ◽  
Scale Yielding

ABSTRACTBy using the elastic singular field as a prescribed loading condition, small scale yielding solutions are obtained for a crack normal to the interface between a brittle and a ductile material. Results for both a crack in the brittle material and one in the ductile material are obtained by finite element analysis. The crack tip fields obtained by the finite element analysis are compared with the asymptotic solutions. It is found that near the tip the stress fields approach the asymptotic solutions. If the crack is in the brittle material, the high triaxial stresses are developed near the interface ahead of the crack tip.

scholarly journals Damage Function of a Quasi-Brittle Material, Damage Rate, Acceleration and Jerk during Uniaxial Compression: Model and Application to Analysis of Trabecular Bone Tissue Destruction

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1759
Author(s):  
Gennady Kolesnikov
Keyword(s):  
Trabecular Bone ◽  
Bone Tissue ◽  
Uniaxial Compression ◽  
Brittle Material ◽  
Brittle Materials ◽  
Practical Interest ◽  
Damage Function ◽  
Rate Acceleration ◽  
Damage Process ◽  
Trabecular Bone Tissue

A diversity of quasi-brittle materials can be observed in various engineering structures and natural objects (rocks, frozen soil, concrete, ceramics, bones, etc.). In order to predict the condition and safety of these objects, a large number of studies aimed at analyzing the strength of quasi-brittle materials has been conducted and presented in publications. However, at the modeling level, the problem of estimating the rate and acceleration of destruction of a quasi-brittle material under loading remains relevant. The purpose of the study was to substantiate the function of damage to a quasi-brittle material under uniaxial compression, determine the rate, acceleration and jerk of the damage process, and also to apply the results obtained to predicting the destruction of trabecular bone tissue. In accordance with the purpose of the study, the basic concepts of fracture mechanics and standard methods of mathematical modeling were used. The proposed model is based on the application of the previously obtained differentiable damage function without parameters. The results of the study are presented in the form of plots and analytical relations for computing the rate, acceleration and jerk of the damage process. Examples are given. The predicted peak of the combined effect of rate, acceleration and jerk of the damage process are found to be of practical interest as an additional criterion for destruction. The simulation results agree with the experimental data known from the available literature.

Modeling Material Removal in Fracture Erosion for Brittle Materials by Abrasive Waterjet

2009 ◽  
Vol 76-78 ◽  
pp. 357-362 ◽  
Author(s):  
Hong Tao Zhu ◽  
Chuan Zhen Huang ◽  
Jun Wang ◽  
Guo Qun Zhao ◽  
Quan Lai Li
Keyword(s):  
Brittle Material ◽  
Material Removal ◽  
Brittle Materials ◽  
Abrasive Waterjet ◽  
Abrasive Waterjet Machining ◽  
Waterjet Machining ◽  
Modeling Material ◽  
Ceramic Glass ◽  
Material Removal Model ◽  
Removal Model

The abrasive waterjet machining is a powerful tool in processing various materials, especially, for brittle materials, such as ceramic, glass and so on. However, the material removal of a brittle material when impacted by abrasive waterjet is not understood in detail. In this paper, the material removal model in fracture erosion of brittle materials by abrasive waterjet has been developed.

Numerical Analysis of Damage Thermo-Mechanical Models

2015 ◽  
Vol 7 (5) ◽  
pp. 625-643 ◽  
Author(s):  
Hamdi Hentati ◽  
Ilyes Ben Naceur ◽  
Wassila Bouzid ◽  
Aref Maalej
Keyword(s):  
Numerical Analysis ◽  
Crack Initiation ◽  
Brittle Material ◽  
Crack Path ◽  
Orthogonal Cutting ◽  
The Other ◽  
Ductile Material ◽  
Global Approach ◽  
Ductile Materials ◽  
Mechanical Models

AbstractIn this paper, we present numerical computational methods for solving the fracture problem in brittle and ductile materials with no prior knowledge of the topology of crack path. Moreover, these methods are capable of modeling the crack initiation. We perform numerical simulations of pieces of brittle material based on global approach and taken into account the thermal effect in crack propagation. On the other hand, we propose also a numerical method for solving the fracture problem in a ductile material based on elements deletion method and also using thermo-mechanical behavior and damage laws. In order to achieve the last purpose, we simulate the orthogonal cutting process.

Some Results in the Erosion of Prestressed Materials due to Water-Jet Impact

1973 ◽  
Vol 15 (4) ◽  
pp. 295-301 ◽  
Author(s):  
G. W. Vickers ◽  
W. Johnson
Keyword(s):  
Brittle Material ◽  
Stress Ratio ◽  
Water Jet ◽  
Ductile Material ◽  
Fracture Modes ◽  
Impact Stress ◽  
Water Jets ◽  
Compressive Stresses ◽  
Jet Impact ◽  
Prestressed Materials

Two methods are described of applying uniaxial and biaxial tensile and compressive stresses to specimens subject to the erosive action of repetitive water jets which have speeds in the range 30–220 m/s. The influence which prestress has on erosion is examined in a ductile material, α-brass, and in a brittle material, Perspex. The behaviour of these materials contrasts sharply due to their different fracture modes. Also the values of prestress to impact stress ratio and the type of stress applied, are shown to have a bearing on results.

Ductile-Regime Grinding: A New Technology for Machining Brittle Materials

1991 ◽  
Vol 113 (2) ◽  
pp. 184-189 ◽  
Author(s):  
T. G. Bifano ◽  
T. A. Dow ◽  
R. O. Scattergood
Keyword(s):  
Material Removal ◽  
New Technology ◽  
Brittle Materials ◽  
Ductile Material ◽  
Grinding Wheel ◽  
Precision Engineering ◽  
Workpiece Material ◽  
Surface Finishes ◽  
Wheel Revolution ◽  
Complex Shapes

Because of recent advances in precision engineering that allow controlled grinding infeed rates as small as several nanometers per grinding wheel revolution, it is possible to grind brittle materials so that the predominant material-removal mechanism is plastic-flow and not fracture. This process is known as ductile-regime grinding. When brittle materials are ground through a process of plastic deformation, surface finishes similar to those achieved in polishing or lapping are produced. Unlike polishing or lapping, however, grinding is a deterministic process, permitting finely controlled contour accuracy and complex shapes. In this paper, the development of a research apparatus capable of ductile-regime grinding is described. Furthermore, an analytical and experimental investigation of the infeed rates necessary for ductile-regime grinding of brittle materials is presented. Finally, a model is proposed, relating the grinding infeed rate necessary for ductile material-removal with the properties of the brittle workpiece material.

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