scholarly journals Mechanism of Unstable Material Removal Modes in Micro Cutting of Silicon Carbide

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 696 ◽  
Author(s):  
Wei Zhao ◽  
Haibo Hong ◽  
Hongzhi Wang
Keyword(s):  
Silicon Carbide ◽  
Material Removal ◽  
Large Scale ◽  
Chip Thickness ◽  
Transitional Zone ◽  
Machined Surface ◽  
Micro Cutting ◽  
Unstable Material ◽  
Ductile Mode ◽  
Sic Wafer

This study conducts large-scale molecular dynamics (MD) simulations of micro cutting of single crystal 6H silicon carbide (SiC) with up to 19 million atoms to investigate the mechanism of unstable material removal modes within the transitional range of undeformed chip thickness in which either brittle or ductile mode of cutting might occur. Under this transitional range, cracks are always formed in the cutting zone, but the stress states cannot guarantee their propagation. The cutting mode is brittle when the cracks can propagate and otherwise ductile mode cutting happens. Plunge cutting experiment is conducted to produce a taper groove on a 6H SiC wafer. There is a transitional zone between the brittle-cut and ductile-cut regions, which has a mostly smooth surface with a few brittle craters on it. This study contributes to the understanding of the detailed process of brittle-ductile cutting mode transition (BDCMT) as it shows that a transitional range can occur even for single crystals without internal defects and provides guidance for the determination of tcritical from taper grooves made by various techniques, e.g., to adopt larger tcritical around the end of the transitional range to increase machining efficiency for grinding or turning as long as the cracks do not extend below the machined surface.

scholarly journals Experimental Optimization of Annular Polishing Parameters for Silicon Carbide

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Yuan Liu ◽  
La Han ◽  
Haiying Liu ◽  
Yikai Shi ◽  
Junjie Zhang
Keyword(s):  
Surface Roughness ◽  
Silicon Carbide ◽  
Surface Quality ◽  
Material Removal ◽  
Polished Surface ◽  
Strong Impact ◽  
Machined Surface ◽  
Experimental Optimization ◽  
Machined Surface Quality ◽  
Influential Parameters

Machined surface quality has a strong impact on the functionality of silicon carbide-based components and devices. In the present work, we first analytically investigate the complex coupling of motions in annular polishing based on the Preston equation, which derives the influential parameters for material removal. Subsequently, we conduct systematic annular polishing experiments of reaction-bonded silicon carbide to investigate the influence of derived parameters on polished surface quality, which yield optimized polishing parameters for achieving ultralow surface roughness of reaction-bonded silicon carbide.

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.

scholarly journals Research on High Performance Milling of Engineering Ceramics from the Perspective of Cutting Variables Setting

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 122
Author(s):  
Rong Bian ◽  
Wenzheng Ding ◽  
Shuqing Liu ◽  
Ning He
Keyword(s):  
Material Removal ◽  
High Performance ◽  
Removal Rate ◽  
Chip Thickness ◽  
Depth Of Cut ◽  
End Mill ◽  
Uncut Chip Thickness ◽  
Machined Surface ◽  
Milling Parameters ◽  
Corner Radius

The setting of cutting variables for precision milling of ceramics is important to both the machined surface quality and material removal rate (MRR). This work specifically aims at the performance of corner radius PCD (polycrystalline diamond) end mill in precision milling of zirconia ceramics with relatively big cutting parameters. The characteristics of the cutting zone in precision milling ceramics with corner radius end mill are analyzed. The relationships between the maximum uncut chip thickness (hmax) and the milling parameters including feed per tooth (fz), axial depth of cut (ap) and tool corner radius (rε) are discussed. Precision milling experiments with exploratory milling parameters that cause uncut chip thickness larger than the critical value were carried out. The material removal mechanism was also analyzed. According to the results, it is advisable to increase fz appropriately during precision milling ZrO2 ceramics with corner radius end mill. There is still a chance to obtain ductile processed surface, as long as the brittle failure area is controlled within a certain range. The appropriate increasing of ap, not only can prevent the brittle damage from affecting the machined surface, but also could increase the MRR. The milling force increases with increasing MRR, but the surface roughness can still be stabilized within a certain range.

Investigation of Size Effect on Micro Hardness of Machined Surface in Micro Cutting

2014 ◽  
Vol 602-605 ◽  
pp. 443-446
Author(s):  
Tao Zhang ◽  
Zhen Yu Shi ◽  
Bing Yan ◽  
Hou Jun Qi
Keyword(s):  
Size Effect ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Three Dimension ◽  
Micro Hardness ◽  
Uncut Chip Thickness ◽  
Machined Surface ◽  
Micro Cutting ◽  
Cutting Edge Radius ◽  
Edge Radius

Micro cutting is a promising way for manufacturing micro parts, especially micro three dimension parts. Micro hardness is an important character to evaluate surface integrity of machined surface. Micro cutting is different from macro cutting due to size effect of specific cutting energy because of the influence of the ratio of uncut chip thickness to cutting edge radius. A group of micro cutting experiments were conducted to investigate the cutting parameters on the micro hardness of machined surface. The micro hardness of machines surface decreases with the ratio of uncut chip thickness to cutting edge radius first, and then increase when the uncut chip thickness is smaller than the cutting edge radius. The micro hardness shows size effect due to the machined surface compressed twice with the round cutting edge. The micro hardness decreases with the distance increasing far away from the machined surface.

Experimental Evaluation of Laser-Assisted Micromilling in a Slotting Configuration

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Jonathan A. Shelton ◽  
Yung C. Shin
Keyword(s):  
Material Removal ◽  
Three Dimensional ◽  
Chip Thickness ◽  
Acoustic Emissions ◽  
Element Model ◽  
Depth Of Cut ◽  
Material Strength ◽  
Machined Surface ◽  
Dimensional Finite Element ◽  
Aisi 316

Micromilling can be difficult to apply to many engineering materials due to a variety of scaling induced factors including low cutting speeds, high relative tool deflections and runout, and increased material strength at smaller size scales. To alleviate these problems, laser-assisted micromilling (LAMM) was evaluated on Ti6Al4V, AISI 422, and AISI 316 using 100 μm diameter endmills in slotting operations. A three-dimensional transient finite-volume based thermal model was used to analytically predict appropriate process parameters on the basis of material removal temperatures. A two-dimensional finite element model was created and used to show the effects of cutting edge radius, uncut chip thickness, and material removal temperature on the cutting force. A thorough experimental investigation of acoustic emissions (AEs) during LAMM was performed. In particular, the effects of depth of cut, tool wear, and material removal temperature on the root-mean-square of AEs were studied. The effects of LAMM on the machined surface finish and edge burrs were also evaluated.

EDM with USM Combination Process of Sintered NdFeB Permanent Magnet

2010 ◽  
Vol 44-47 ◽  
pp. 1066-1069
Author(s):  
Li Li ◽  
Li Ling Qi ◽  
Zong Wei Niu
Keyword(s):  
Permanent Magnet ◽  
Material Removal ◽  
Removal Rate ◽  
Surface Characteristics ◽  
Dielectric Fluid ◽  
Machined Surface ◽  
Combination Process ◽  
Electro Discharge Machining ◽  
Ndfeb Permanent Magnet ◽  
Machining Characteristics

This paper presents an experimental investigation of the machining characteristics of sintered NdFeB permanent magnet using a combination process of electro-discharge machining (EDM) with ultrasonic machining (USM). Concentration of abrasive in the dielectric fluid is changed to explore its effect on the material removal rate (MRR). MRR of EDM /USM, conventional EDM are compared, machined surface characteristics are also compared between them. It is concluded that the combination EDM/USM process can increase the MRR and decrease the thickness of the recast layer. In the combination process, an appropriate abrasive concentration can improve its machining efficiency.

Effect of Process Parameters on Material Removal Rate in Chemical Mechanical Polishing of 6H-SiC(0001)

2008 ◽  
Vol 600-603 ◽  
pp. 831-834 ◽  
Author(s):  
Joon Ho An ◽  
Gi Sub Lee ◽  
Won Jae Lee ◽  
Byoung Chul Shin ◽  
Jung Doo Seo ◽  
...  
Keyword(s):  
Material Removal Rate ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Colloidal Silica ◽  
Removal Rate ◽  
Mechanical Polishing ◽  
Diamond Particles ◽  
Average Grain Size ◽  
Silica Slurry ◽  
Sic Wafer

2inch 6H-SiC (0001) wafers were sliced from the ingot grown by a conventional physical vapor transport (PVT) method using an abrasive multi-wire saw. While sliced SiC wafers lapped by a slurry with 1~9㎛ diamond particles had a mean height (Ra) value of 40nm, wafers after the final mechanical polishing using the slurry of 0.1㎛ diamond particles exhibited Ra of 4Å. In this study, we focused on investigation into the effect of the slurry type of chemical mechanical polishing (CMP) on the material removal rate of SiC materials and the change in surface roughness by adding abrasives and oxidizer to conventional KOH-based colloidal silica slurry. The nano-sized diamond slurry (average grain size of 25nm) added in KOH-based colloidal silica slurry resulted in a material removal rate (MRR) of 0.07mg/hr and the Ra of 1.811Å. The addition of oxidizer (NaOCl) in the nano-size diamond and KOH based colloidal silica slurry was proven to improve the CMP characteristics for SiC wafer, having a MRR of 0.3mg/hr and Ra of 1.087Å.

scholarly journals Machining-Induced Work Hardening Behavior of Inconel 718 Considering Edge Geometries

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 397
Author(s):  
Bin Zhou ◽  
Weiwei Zhang ◽  
Zhongmei Gao ◽  
Guoqiang Luo
Keyword(s):  
Grain Size ◽  
Work Hardening ◽  
Inconel 718 ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Machined Surface ◽  
Work Hardening Behavior ◽  
Hardening Behavior ◽  
Significant Difference ◽  
Optimization Of Cutting Parameters

As a representative type of superalloy, Inconel 718 is widely employed in aerospace, marine and nuclear industries. The significant work hardening behavior of Inconel 718 can improve the service performance of components; nevertheless, it cause extreme difficulty in machining. This paper aims to investigate the influence of chamfered edge parameters on work hardening in orthogonal cutting of Inconel 718 based on a novel hybrid method, which integrates Coupled Eulerian-Lagrangian (CEL) method and grain-size-based functions considering the influence of grain size on microhardness. Orthogonal cutting experiments and nanoindentation tests are conducted to validate the effectiveness of the proposed method. The predicted results are highly consistent with the experimental results. The depth of work hardening layer increases with increasing chamfer angle and chamfer width, also with increasing feed rate (the uncut chip thickness). However, the maximum microhardness on the machined surface does not exhibit a significant difference. The proposed method can provide theoretical guidance for the optimization of cutting parameters and improvement of the work hardening.

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