Probabilistic model of surface layer removal when grinding brittle non-metallic materials

2021 ◽  
Vol 23 (2) ◽  
pp. 6-16
Author(s):  
Sergey Bratan ◽  
◽  
Stanislav Roshchupkin ◽  
Alexander Kharchenko ◽  
Anastasia Chasovitina ◽  
...  
Keyword(s):  
Surface Layer ◽  
Contact Zone ◽  
Probabilistic Model ◽  
Material Removal ◽  
Brittle Materials ◽  
Grinding Wheel ◽  
Metallic Materials ◽  
Deformable Solid ◽  
Metallic Material ◽  
Wide Range

Introduction. The final quality of products is formed during finishing operations, which include the grinding process. It is known that when grinding brittle materials, the cost of grinding work increases significantly. It is possible to reduce the scatter of product quality indicators when grinding brittle materials, as well as to increase the reliability and efficiency of the operation, by choosing the optimal parameters of the technological system based on dynamic models of the process. However, to describe the regularities of the removal of particles of a brittle non-metallic material and the wear of the surface of the grinding wheel in the contact zone, the known models do not allow taking into account the peculiarities of the process in which micro-cutting and brittle chipping of the material are combined. Purpose of the work: to create a new probabilistic model for removing the surface layer when grinding brittle non-metallic materials. The task is to study the laws governing the removal of particles of brittle non-metallic material in the contact zone. In this work, the removal of material in the contact zone as a result of microcutting and brittle chipping is considered as a random event. The research methods are mathematical and physical simulation using the basic provisions of the theory of probability, the laws of distribution of random variables, as well as the theory of cutting and the theory of a deformable solid. Results and discussion. The developed mathematical models make it possible to trace the effect on material removal of the overlap of single cuts on each other when grinding holes in ceramic materials. The proposed dependences show the regularity of stock removal within the arc of contact of the grinding wheel with the workpiece. The considered features of the change in the probability of material removal upon contact of the treated surface with an abrasive tool and the proposed analytical dependences are valid for a wide range of grinding modes, wheel characteristics and a number of other technological factors. The obtained expressions make it possible to find the amount of material removal also for schemes of end, flat and circular external grinding, for which it is necessary to know the amount of removal increment due to brittle fracture during the development of microcracks in the surface layer. One of the ways to determine the magnitude of this increment is to simulate the crack formation process using a computer. The presented results confirm the prospects of the developed approach to simulate the processes of mechanical processing of brittle non-metallic materials.

Simulation of the stock removal in the contact zone during internal grinding of brittle non-metallic materials

2021 ◽  
Vol 23 (2) ◽  
pp. 31-39
Author(s):  
Sergey Bratan ◽  
◽  
Stanislav Roshchupkin ◽  
Alexander Kharchenko ◽  
Anastasia Chasovitina ◽  
...  
Keyword(s):  
Contact Zone ◽  
Material Removal ◽  
Physical Simulation ◽  
Analytical Models ◽  
Abrasive Tool ◽  
Metallic Materials ◽  
Deformable Solid ◽  
Internal Grinding ◽  
Wide Range ◽  
Stock Removal

Introduction. Finishing operations, in particular, cylindrical grinding, essentially form the quality parameters of products, its performance characteristics and functional suitability. At the same time, the cost of grinding work increases significantly in comparison with grinding metals, reaching an average of 20 ... 28% of the total cost of manufacturing products. The selection of the optimal parameters of the technological system based on the process simulation can improve the reliability, productivity and economic efficiency. To describe the processing of brittle nonmetallic materials, empirical dependences are mainly used, and the existing analytical models do not take into account the stochastic nature of the grinding operation and the combination of microcutting and brittle chipping when removing particles of brittle nonmetallic material and wear of the surface of the grinding tool. Purpose of the work: simulation of stock removal in the contact zone during internal grinding of brittle non-metallic materials. The task is to study the features and patterns of change in the probability of material removal when the treated surface comes into contact with an abrasive tool. In the work, the theoretical and probabilistic models are obtained, allowing to reveal the patterns of material removal in the contact zone. The models make it possible to trace the regularities of the interaction of cutting and piercing grains on the surface of the workpiece and the process of removing the allowance in the contact zone due to a combination of the phenomena of microcutting and brittle chipping, considered as a random event. The research methods are mathematical and physical simulation using the basic provisions of the theory of probability, the laws of distribution of random variables, as well as the theory of cutting and the theory of a deformable solid. Results and discussion. Data are obtained that provide a clear illustration of the patterns of material removal along the contact zone at various levels. Analysis of the results obtained shows that the peripheral speed of the tool and the rotation speed of the workpiece, which are directly included in the equation for calculating the probability of material removal, significantly affect the rate of material removal. The cross feed also has a significant effect on stock removal. A qualitative picture of the change in the probability of material removal in the contact zone during grinding of holes in brittle nonmetallic materials is obtained. The obtained patterns of change in the probability of material removal when the machined surface is in contact with an abrasive tool and analytical dependences are valid for a wide range of grinding modes, tool characteristics and other technological factors.

Analysis of the Tribological Conditions in Grinding of Polycrystalline Diamond Based on Single Grain Friction Tests Using the Pin-Disk Principle

2018 ◽  
Vol 767 ◽  
pp. 259-267 ◽  
Author(s):  
Frederik Vits ◽  
Daniel Trauth ◽  
Patrick Mattfeld ◽  
Rudolf Vits ◽  
Fritz Klocke
Keyword(s):  
Contact Zone ◽  
Material Removal ◽  
Polycrystalline Diamond ◽  
Grinding Wheel ◽  
Grinding Process ◽  
State Variables ◽  
Wheel Wear ◽  
Grinding Wheel Wear ◽  
Single Grain ◽  
Zone Temperature

Cutting tools made of polycrystalline diamond (PCD) are used for machining of aluminum alloys, fiber-reinforced plastic composites and wood. Compared to cemented carbide tools with geometrically defined cutting edges, PCD tools offer significant advantages with respect to tool life. High demands regarding the cutting edge roughness and the quality of the rake and the flank face usually require a grinding process with diamond grinding wheels. The PCD grinding process, however, is characterized by low material removal rates and high grinding wheel wear. The material removal rate and the grinding wheel wear, in turn, highly depend on the process state variables process force and process temperature. However, the relationship between these process state variables and the process input variables is largely unknown. This work provides a contribution to the closure of this knowledge gap by means of an adapted friction law. A single grain friction test stand using the pin-disk principle was developed, which enables a measurement of the friction force and the contact zone temperature for normal forces and relative speeds that are common in PCD grinding. During the experiments, the specification of the PCD disc, the cross-sectional area of the friction sample made of monocrystalline diamond as well as the process parameters normal force and relative speed were varied. In addition, the tests were carried out without lubrication as well as with a minimum lubrication. A high correlation between the contact force and the coefficient of friction was determined. This relationship was mathematically formulated in a friction law. In addition, a direct influence of the contact force and the relative velocity on the contact zone temperature was identified. The knowledge gained leads to an improved understanding of the PCD grinding process and thus enables a more efficient grinding process design.

Contact Zone Force Profile and Machining Performance of Filamentary Brush1

2005 ◽  
Vol 127 (1) ◽  
pp. 217-226 ◽  
Author(s):  
R. J. Stango ◽  
V. Cariapa ◽  
M. Zuzanski
Keyword(s):  
Contact Zone ◽  
Material Removal ◽  
Removal Rate ◽  
Contact Region ◽  
Force Sensor ◽  
Surface Finishing ◽  
Production Environment ◽  
Machining Performance ◽  
Wide Range ◽  
Force Profile

Filamentary brushing tools are used in a wide range of surface finishing processes, such as deburring, edge radiusing, polishing, and surface decontamination applications. Moreover, these tools are easily adapted to automation because the filament tips, which perform the machining operation, readily conform to the workpart surface without the need for sophisticated control systems technology. However, little is known about the material removal mechanics of filamentary brushes and, therefore, trial-and-error experimentation is often necessary before the tool is implemented in a production environment. This uncertainty of performance can be traced to a lack of understanding of the actual forces that are generated within the contact zone, that is, along the interface of the filament tip and workpart surface. Although previous experimental research has focused on the overall (i.e., resultant) brush force exerted onto the workpart, no information exists in the literature regarding the variation of force within the contact zone. Such information is essential for understanding the material removal profile within the contact zone, and could provide valuable information regarding the most active machining site along the contact surface. In this paper, a novel experiment is proposed for evaluating the force profile of filament tip forces that are generated within the contact region of a brushed surface. A specially designed workpart fixture is constructed and used in conjunction with a multiaxis force sensor for measuring the detailed force variation within the contact zone. The experiment is conducted using a wire brush at several different rotational speeds, which enables one to ascertain the role of filament inertia in the material removal process. Findings are reported which suggest that a significantly enhanced material removal rate can be achieved at a selective location within the contact zone at moderately elevated spindle speeds.

Giant pop-ins in nanoindented silicon and germanium caused by lateral cracking

2008 ◽  
Vol 23 (2) ◽  
pp. 297-301 ◽  
Author(s):  
D.J. Oliver ◽  
B.R. Lawn ◽  
R.F. Cook ◽  
M.G. Reitsma ◽  
J.E. Bradby ◽  
...  
Keyword(s):  
Contact Zone ◽  
Material Removal ◽  
Microelectromechanical Systems ◽  
Crystalline Silicon ◽  
Brittle Materials ◽  
Indentation Load ◽  
High Load ◽  
Silicon And Germanium

Giant “pop-in” displacements are observed in crystalline silicon and germanium during high-load nanoindentation with a spherical diamond tip. These events are consistent with material removal triggered by lateral cracking during loading, which poses a hazard to microelectromechanical systems (MEMS) operation. We examine the scaling of the pop-in displacements as a function of peak indentation load and demonstrate a correlation with the depth of the plastic contact zone. We argue that giant pop-ins may occur in a broad range of highly brittle materials.

scholarly journals Study of structural changes in metallic materials subjected to shock stress

2018 ◽  
Vol 178 ◽  
pp. 04011
Author(s):  
Sorin Cristea ◽  
Marius Bibu
Keyword(s):  
Alloy Steel ◽  
Structural Changes ◽  
Layered Materials ◽  
Material Behavior ◽  
Impact Point ◽  
Metallic Materials ◽  
Metallic Material ◽  
Wide Range ◽  
The Impact ◽  
Shock Stress

Behavior analysis of materials subjected to extreme demands remains a topical field for a wide range of engineering applications. The materials in discussion are in increasing numbers composites or layered materials, but homogeneous materials are not neglected either. The paper addresses the topic of a homogeneous metallic material subjected to shock loads. Two different thicknesses of alloy steel of known composition were used. Thicknesses used were of 4 mm and 6 mm respectively. After the loads were applied, the samples were cut in the direction of planes passing through the impact point; the microdurity was measured in the crosssection obtained and the medium microdurity areas were plotted. The obtained results allowed the identification of particularities in material behavior, in relation with the thickness, for the same values of the shock energy load and same shape of the penetrator.

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.

Calculation of radial material removal and the thickness of the layer with the current roughness when grinding brittle non-metallic materials

2021 ◽  
Vol 23 (3) ◽  
pp. 31-44
Author(s):  
Sergey Bratan ◽  
◽  
Stanislav Roshchupkin ◽  
Aleksander Kharchenko ◽  
Anastasia Chasovitina ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Removal ◽  
Physical Simulation ◽  
Surface Condition ◽  
Grinding Wheel ◽  
Metallic Materials ◽  
Machined Surface ◽  
Micro Cutting ◽  
Real Process ◽  
Experimental Values

Introduction. The quality parameters of products, which determine its performance and functionality, are finally formed in the finishing operations, which include the internal grinding process. In this case, the removal of material from the rough surface of the workpiece occurs due to the presence of several simultaneously running random processes of shaping, occurring during the contact of the grinding wheel and the workpiece. A probabilistic theoretical approach is used to simulate grinding operations. However, for determination of radial material removal and thickness of layer with current roughness, the known models cannot be used, as it does not allow taking into account specific features of machining products made of brittle non-metallic materials. Purpose of the work. Creation of a new theoretical and probabilistic model allowing to calculate radial material removal and layer thickness, in which current roughness is distributed during grinding of brittle non-metallic materials. The aim is to investigate the regularities of brittle non-metallic material particles removal by radial removal and study the current (for the moment) roughness formed after every radial removal in the contact area. In the work, radial material removal and the layer with current roughness are determined by grinding modes, tool surface condition, workpiece and wheel dimensions, and the initial condition of the machined surface after the previous contact. The research methods are mathematical and physical simulation using basic probability theory, distribution laws of random variables, as well as the theory of cutting and the theory of deformable solids. Results and discussion. The developed mathematical models make it possible to trace the dimensions and shape of the contact zone when grinding holes in billets made of silicon, which are somewhat different from those known when machining billets made of metal. The proposed dependencies show that with an increase in the depth of micro-cutting, the radial material removal and the thickness of the layer with the current surface roughness increase for all values of wheel speed and workpiece speed. From the experimental values obtained, the maximum micro-cutting depth and the thickness of the layer with current surface roughness are calculated. The thickness of the said layer is compared with the experimental values obtained from the ground surface profilographs. A comparison of the calculated and experimental data indicates its compliance with almost all feed values, which confirms the adequacy of the obtained equations, which model the real process of grinding holes made of brittle non-metallic materials quite well.

Cutting Forces Calculation at Diamond Grinding of Brittle Materials

2015 ◽  
Vol 770 ◽  
pp. 163-168 ◽  
Author(s):  
M.A. Shavva ◽  
S.V. Grubiy
Keyword(s):  
Contact Zone ◽  
Glass Ceramic ◽  
Cutting Forces ◽  
Brittle Materials ◽  
Grinding Wheel ◽  
Grinding Forces ◽  
Method Of Calculation ◽  
Diamond Grinding ◽  
Single Grain ◽  
Measuring Force

A method of calculation of cutting forces at diamond grinding of brittle materials is proposed in article. The cutting forces: normal, tangential and fracture, acting to single grain are calculated. Total grinding forces are defined by average number of grain in contact zone. Calculating values of forces are compared with result of experimental approximation of measuring force at grinding of glass-ceramic workpiece. Grinding forces increase with increasing of diamond grains wear and can be indicative of grinding wheel blunting.

Sandwich Panels Made of Perforated Metal Materials

2021 ◽  
Vol 320 ◽  
pp. 155-160
Author(s):  
Viktor Mironov ◽  
Mihails Lisicins ◽  
Irina Boiko
Keyword(s):  
Experimental Studies ◽  
Sandwich Panels ◽  
Skin Layer ◽  
Core Material ◽  
Metallic Materials ◽  
Element Analysis ◽  
Metallic Material ◽  
Wide Range ◽  
The Finite Element Analysis ◽  
Metallic Sheet

Nowadays, the growing attention has focused on the sandwich-structured composites (panels), especially on those, which are environmentally friendly. The sandwich panel is a special type of the composites made of at least three layers: a core and a skin-layer bonded to each side. The aim of this paper is to investigate the possibility of using of perforated metallic materials for producing sandwich panels for the different application in the civil engineering. By using the perforated metallic materials in combination with different core materials or by using the perforated metallic material as the core material the wide range of products for the construction, damping or isolation purposes could be manufactured. In the paper the example of using of perforated metallic sheet materials for manufacturing the sandwich panels is proposed. Both, the simulation and experimental studies (mechanical testing) were carried out in order to assess the load-bearing capacity of sandwich panels and to prove the applicability of the proposed sandwich panels for construction structures. For the analysis of the achieved structures the finite element analysis (FEA) software was used. The simulation results are well-coincided with the results of the experimental studies. Thus, new types of the sandwich panels and the manufacturing technology thereof are shown its reliability and could be recommended for application in the different branches, in particular for producing lightweight ceiling panels with filler from heat insulating materials.

Contact Zone Force Profile and Machining Performance of Filamentary Brush

Manufacturing ◽  
2002 ◽  
Author(s):  
Robert J. Stango ◽  
Vikram Cariapa ◽  
Mark Zuzanski
Keyword(s):  
Contact Zone ◽  
Material Removal ◽  
Removal Rate ◽  
Contact Region ◽  
Force Sensor ◽  
Surface Finishing ◽  
Production Environment ◽  
Machining Performance ◽  
Wide Range ◽  
Force Profile

Filamentary brushing tools are used in a wide range of surface finishing processes, such as deburring, edge radiusing, polishing, and surface decontamination applications. Moreover, these tools are easily adapted to automation because the filament tips, which perform the machining operation, readily conform to the workpart surface without the need for sophisticated control systems technology. However, little is known about the material removal mechanics of filamentary brushes and, therefore, trial-and-error experimentation is often necessary before the tool is implemented in a production environment. This uncertainty of performance can be traced to a lack of understanding of the actual forces that are generated within the contact zone, that is, along the interface of the filament tip and workpart surface. Although previous experimental research has focused on the overall (i.e., resultant) brush force exerted onto the workpart, no information exists in the literature regarding the variation of force within the contact zone. Such information is essential for understanding the material removal profile within the contact zone, and could provide valuable information regarding the most active machining site along the contact surface. In this paper, a novel experiment is proposed for evaluating the force profile of filament tip forces that are generated within the contact region of a brushed surface. A specially designed workpart fixture is constructed and used in conjunction with a multi-axis force sensor for measuring the detailed force variation within the contact zone. The experiment is conducted using a wire brush at several different rotational speeds, which enables one to ascertain the role of filament inertia in the material removal process. Findings are reported which suggest that a significantly enhanced material removal rate can be achieved at a selective location within the contact zone at moderately elevated spindle speeds.

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