scholarly journals Effect of Thermal Softening on Anisotropy and Ductile Mode Cutting of Sapphire Using Micro-Laser Assisted Machining

2017 ◽  
Vol 5 (1) ◽  
Author(s):  
Hossein Mohammadi ◽  
John A. Patten
Keyword(s):  
Removal Rate ◽  
Brittle Materials ◽  
Single Crystal Silicon ◽  
Thermal Softening ◽  
Depth Of Cut ◽  
Crystal Silicon ◽  
Ductile Mode ◽  
Hard And Brittle Materials ◽  
Fracture Damage ◽  
Diamond Cutting Tool

Ceramics and semiconductors have many applications in optics, micro-electro-mechanical systems, and electronic industries due to their desirable properties. In most of these applications, these materials should have a smooth surface without any surface and subsurface damages. Avoiding these damages yet achieving high material removal rate in the machining of them is very challenging as they are extremely hard and brittle. Materials such as single crystal silicon and sapphire have a crystal orientation or anisotropy effect. Because of this characteristic, their mechanical properties vary significantly by orientation that makes their machining even more difficult. In previous works, it has been shown that it is possible to machine brittle materials in ductile mode. In the present study, scratch tests were accomplished on the monocrystal sapphire in four different perpendicular directions. A laser is transmitted to a diamond cutting tool to heat and soften the material to either enhance the ductility, resulting in a deeper cut, or reducing brittleness leading to decreased fracture damage. Results such as depth of cut and also nature of cut (ductile or brittle) for different directions, laser powers, and cutting loads are compared. Also, influence of thermal softening on ductile response and its correlation to the anisotropy properties of sapphire is investigated. The effect of thermal softening on cuts is studied by analyzing the image of cuts and verifying the depth of cuts which were made by using varying thrust load and laser power. Macroscopic plastic deformation (chips and surface) occurring under high contract pressures and high temperatures is presented.

Custom Micro Tooling for Mechanical Ductile-Mode Micro/Nano Machining of Hard and Brittle Materials

2012 ◽  
Vol 426 ◽  
pp. 20-23
Author(s):  
Xiang Cheng ◽  
Xi Zhang ◽  
J.Y. Liu ◽  
X.H. Yang ◽  
Z.Q. Tian
Keyword(s):  
Three Dimensional ◽  
Brittle Materials ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Factors Affecting ◽  
Ductile Mode ◽  
Hard And Brittle Materials ◽  
Micro Tooling ◽  
Key Aspects ◽  
Micro Tools

Hard and brittle materials such as WC, SiC, and single crystal silicon or germanium are widely used in die/moulds for very high accuracy glass products, medical devices, and sensors for MEMS. Mechanical ductile-mode micro/nano milling is an effective method to create three dimensional geometries on these materials. One of the key factors affecting successfully ductile-mode machining is micro tooling. Due to limitations of commercially available micro tools, custom micro tooling is brought forward to give an active solution to this issue. This paper is a further study on custom micro tooling by the author, and several aspects associated with custom micro tooling have been discussed. Experimental results show the feasibility and effectiveness of the successful ductile-mode machining of hard and brittle materials by custom micro tooling. At last, this paper summarizes the techniques associated with custom micro tooling and point out the key aspects for further research on custom micro tooling.

Thrust Force Directional Vibration-Assisted Ductile-Mode Grinding of Single-Crystal Si

2010 ◽  
Vol 126-128 ◽  
pp. 627-632 ◽  
Author(s):  
Kenichiro Imai ◽  
Hiroshi Hashimoto
Keyword(s):  
Single Crystal ◽  
Thrust Force ◽  
Removal Rate ◽  
Single Crystal Silicon ◽  
Grinding Force ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Crystal Silicon ◽  
Ductile Mode ◽  
Single Grain

Under optimum grinding conditions, a constant grinding force is exerted on a workpiece during ductile-mode grinding of BK7 glass. Based on the results, the cutting force, specific grinding energy, and depth of cut for a single grain were calculated. It was found that a single grain was easily removed from the material. However, grinding is impossible because surface burning occurs on the workpiece. In order to avoid burning, a single-crystal silicon wafer (1,0,0) surface was ground with thrust force directional vibration-assisted grinding. The normal grinding force with vibration was comparatively low, but was quite stable. The removal rate was approximately three times greater than that without vibration. The results indicate that the successive abrasive grains of the grinding wheel remove the material intermittently.

Anisotropy Effect on Cutting Monocrystal Sapphire by Micro-Laser Assisted Machining Technique

2016 ◽  
Author(s):  
Hossein Mohammadi ◽  
John A. Patten
Keyword(s):  
Laser Heating ◽  
Removal Rate ◽  
Single Point ◽  
Brittle Materials ◽  
Single Crystal Silicon ◽  
Shear Stresses ◽  
Crystal Silicon ◽  
Anisotropy Effect ◽  
Fracture Damage ◽  
Scratch Tests

Machining of hard and brittle materials such as ceramics and semiconductors has been a challenge for many years. They have many applications in optics, MEMS and electronic industries due to their many desirable properties, such as being light weight, strong, and hard. Achieving good surface finish, avoiding surface and subsurface damage and at the same time achieving a high material removal rate are extremely challenging for these materials. Materials such as single crystal silicon and sapphire have a crystal orientation or anisotropy effect which makes their machining even more difficult. Because of this characteristic, their behavior is directional and they have different fracture toughness for each direction. In past works in our research group, it has been demonstrated that machining of brittle materials in ductile regime is possible due to the high pressure phase transformation (HPPT) occurring in the material caused by the high compressive and shear stresses induced by a single point diamond tool tip. In the current study scratch tests were performed on the monocrystal sapphire in four different perpendicular directions and to further augment the process, traditional cutting is coupled with a laser to heat and soften the material to either enhance the ductility, resulting in a deeper cut, or reducing brittleness leading to decreased fracture damage. Results of scratch tests, with and without laser heating, for different cutting loads have been compared. The effect of laser heating was studied by analyzing the image of cuts and verifying the depth of cuts which were made using varying laser power during the process. Microscopic images and three-dimensional profiles of the cuts taken by using a white light interferometer were investigated.

Experimental Investigation of Brittle to Ductile Transition of Single Crystal Silicon by Single Grain Grinding

2007 ◽  
Vol 329 ◽  
pp. 433-438 ◽  
Author(s):  
Feng Wei Huo ◽  
Zhu Ji Jin ◽  
Fu Ling Zhao ◽  
Ren Ke Kang ◽  
Dong Ming Guo
Keyword(s):  
Single Crystal ◽  
Transition Point ◽  
Single Crystal Silicon ◽  
Depth Of Cut ◽  
Surface Cracks ◽  
Crystal Silicon ◽  
Brittle To Ductile Transition ◽  
Ductile Mode ◽  
Single Grain ◽  
Brittle Mode

Grinding of single crystal silicon may be achieved by two modes of material removal: ductile mode and brittle mode. Knowing of the brittle to ductile transition point at which the grinding process changes from the brittle mode to ductile mode is critically important for the realization of ductile mode grinding. This paper uses a new single grain diamond grinding method developed recently by the authors to investigate the brittle to ductile transition during grinding of single crystal silicon in all around. The results indicate that there exist four stages of brittle to ductile transition as the depth of cut is reduced: firstly, the surface cracks outside the grinding groove disappeared, secondlycracks on the bottom of the groove disappeared, then the lateral cracks ceased in the subsurface region, and finally the median crack is suppressed beneath the grooves. It is not until the depth of cut reaches the last transition point that a crack-free groove can be produced, therefore, the last transition stage is decisive. The critical depth of cut delineating the brittle to ductile transition point derived based on this criterion is 40 nanometers, which is much lower than that based on surface cracks.

Critical Depth of Cut and Specific Cutting Energy of a Microscribing Process for Hard and Brittle Materials

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Jiunn-Jyh Junz Wang ◽  
Yong-Yuan Liao
Keyword(s):  
Brittle Materials ◽  
Depth Of Cut ◽  
Specific Cutting Energy ◽  
Critical Depth ◽  
Cutting Depth ◽  
Crystal Silicon ◽  
Cutting Energy ◽  
Process Characteristics ◽  
Hard And Brittle Materials ◽  
Critical Depth Of Cut

This paper investigated the scribing process characteristics of the hard and brittle materials including single crystal silicon, STV glass, and sapphire substrate. Under various cutting angles, major process characteristics are examined including the groove geometry, specific cutting energy, and critical depth of cut at the onset of ductile-to-brittle cutting transition. As the cutting depth increases, groove geometry clearly reveals the ductile-to-brittle transition from the plastic deformation to a brittle fracture state. The material size effect in the ductile region as well as the transition in scribing behavior is well reflected by change in the specific cutting energy. Further, it is shown that the change of specific cutting energy as a function of the cutting depth can serve as a criterion for estimating the critical depth of cut. Such estimated critical depth of cut is confirmed by measurement from a 3D confocal microscope. The critical depths of cut for these hard materials are found to be between 0.1μm and 0.5μm depending on the materials and cutting angles.

scholarly journals Novel Abrasive-Impregnated Pads and Diamond Plates for the Grinding and Lapping of Single-Crystal Silicon Carbide Wafers

2021 ◽  
Vol 11 (4) ◽  
pp. 1783
Author(s):  
Ming-Yi Tsai ◽  
Kun-Ying Li ◽  
Sun-Yu Ji
Keyword(s):  
Silicon Carbide ◽  
Wear Rate ◽  
Single Crystal ◽  
Traditional Method ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Diamond Grit ◽  
Ceramic Binder

In this study, special ceramic grinding plates impregnated with diamond grit and other abrasives, as well as self-made lapping plates, were used to prepare the surface of single-crystal silicon carbide (SiC) wafers. This novel approach enhanced the process and reduced the final chemical mechanical planarization (CMP) polishing time. Two different grinding plates with pads impregnated with mixed abrasives were prepared: one with self-modified diamond + SiC and a ceramic binder and one with self-modified diamond + SiO2 + Al2O3 + SiC and a ceramic binder. The surface properties and removal rate of the SiC substrate were investigated and a comparison with the traditional method was conducted. The experimental results showed that the material removal rate (MRR) was higher for the SiC substrate with the mixed abrasive lapping plate than for the traditional method. The grinding wear rate could be reduced by 31.6%. The surface roughness of the samples polished using the diamond-impregnated lapping plate was markedly better than that of the samples polished using the copper plate. However, while the surface finish was better and the grinding efficiency was high, the wear rate of the mixed abrasive-impregnated polishing plates was high. This was a clear indication that this novel method was effective and could be used for SiC grinding and lapping.

Optimization of Cutting Parameters for High Speed End Milling of Single Crystal Silicon by Diamond Coated Tools with Compressed Air Blowing Using RSM

2012 ◽  
Vol 576 ◽  
pp. 46-50 ◽  
Author(s):  
M.A. Mahmud ◽  
A.K.M. Nurul Amin ◽  
M.D. Arif
Keyword(s):  
Single Crystal ◽  
High Speed ◽  
End Milling ◽  
Single Crystal Silicon ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Crystal Silicon ◽  
Design Expert ◽  
Coated Tools ◽  
Optimization Of Cutting Parameters

This paper presents the thorough experimental analysis on high speed end milling of single crystal silicon using diamond coated tools. Experiments were conducted on CNC milling machine. The design of the experiments was based on the central composite design (CCD) technique of Design Expert software. Response Surface Methodology (RSM) was used to develop mathematical imperial model to establish a correlation between machining parameters (cutting speed, feed and depth of cut) and machined surface roughness in high speed end milling of single crystal silicon using 2mm diameter diamond coated tools. The optimum machining parameters were determined using the optimization tool of Design Expert software based on the desirability function. Finally, confirmation tests were performed to validate the developed model.

CONTROL OF GRAIN, DEPTH OF CUT IN DUCTILE MODE GRINDING OF BRITTLE MATERIALS AND PRACTICAL APPLICATION

1997 ◽  
Author(s):  
AKIRA KANAI ◽  
MASAKAZU MIYASHITA ◽  
FUMIO INABA ◽  
MASAKAZU SATO ◽  
TADASHI YOKOTSUKA ◽  
...  
Keyword(s):  
Brittle Materials ◽  
Depth Of Cut ◽  
Practical Application ◽  
Ductile Mode

Study on Fixed Abrasive Lapping Hard and Brittle Materials with Brazed Micro Powder Diamond Disk

2013 ◽  
Vol 589-590 ◽  
pp. 451-456 ◽  
Author(s):  
Quan Cheng Li ◽  
Jian Yun Shen ◽  
Cong Fu Fang ◽  
Xi Peng Xu
Keyword(s):  
Surface Morphology ◽  
Silicon Wafer ◽  
Removal Rate ◽  
Brittle Materials ◽  
Alumina Ceramic ◽  
Diamond Disk ◽  
Hard And Brittle Materials ◽  
Fixed Abrasive

In this study, two different arrangement lapping disks fixed with brazed diamond pellets were used to lap silicon wafer and alumina ceramic. The effects of the surface morphology, roughness, and removal rate of workpiece caused by lapping pressure, lapping time, workpiece velocity, and disc arrangement were operated with serials experiments. The results of the researches provided guidance for fixed abrasive lapping of hard and brittle materials with the brazed micro powder diamond disk.

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