scholarly journals The importance of wavelength for tight temperature control during μ-laser-assisted machining

2020 ◽  
pp. 251659842091786
Author(s):  
Ashley Dennis ◽  
Saurav Goel ◽  
Rajab Al-Sayegh ◽  
William O’Neill
Keyword(s):  
Temperature Control ◽  
Yttrium Aluminum Garnet ◽  
Continuous Wave ◽  
Removal Rate ◽  
Single Point ◽  
Laser Wavelength ◽  
Diamond Turning ◽  
Laser Assisted Machining ◽  
Ductile Machining ◽  
Machining Properties

The area of single point diamond turning of brittle materials like semiconductors and ceramics is significantly benefitted by incorporation of laser assistance. In a new developmental technology that is now recognized as micro-laser-assisted machining (μ-LAM), a laser is shone through a diamond tool to soften the high-pressure phase transformed ductile machining phases that in turn allows thermal softening and thereby enables a higher material removal rate during ductile mode machining. One of the lasers currently used in μ-LAM is the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser operating at 100 W (continuous wave) at the wavelength of 1064 nm. Although this configuration has worked to the benefit of the technology, here we report futuristic developments that will significantly enhance temperature control by selecting a laser wavelength according to the material being machined, allowing tunable machining properties. The concept is illustrated with sample calculations for μ-LAM of silicon, and it appears to offer better target temperatures, thus enhancing the performance of the μ-LAM process.

Single Point Diamond Turning of Silicon by Using Micro-Laser Assisted Machining Technique

2014 ◽  
Author(s):  
Hossein Mohammadi ◽  
H. Bogac Poyraz ◽  
Deepak Ravindra ◽  
John A. Patten
Keyword(s):  
Fiber Laser ◽  
Cutting Tool ◽  
Single Point ◽  
Diamond Turning ◽  
Depth Of Cut ◽  
Beam Diameter ◽  
Diamond Cutting ◽  
Laser Assisted Machining ◽  
Diamond Cutting Tool ◽  
Si Wafer

In this study, single point diamond turning (SPDT) is coupled with the micro-laser assisted machining (μ-LAM) technique. The μ-LAM system is used to preferentially heat and thermally soften the work piece material in contact with a diamond cutting tool. In μ-LAM the laser and cutting tool are integrated into a single package, i.e. the laser energy is delivered by a single mode fiber laser to and through a diamond cutting tool. This hybrid method can potentially increase the critical depth of cut (DoC), i.e., a larger ductile-to-brittle transition (DBT) depth, in ductile regime machining, resulting in a higher material removal rate (MRR). An IR continuous wave (CW) fiber laser, wavelength of 1064nm and max power of 100W with a beam diameter of 10μm, is used in this investigation. In the current study SPDT tests were employed on single crystal silicon (Si) wafer which is very brittle and hard to machine by conventional methods. Different outputs such as surface roughness and depth of cut for different set of experiments were analyzed. Results show that an unpolished surface of a Si wafer can be machined in one pass to get a very good surface finish. The Ra was brought down from 1.2μm to 275nm only in one pass which is a very promising result for machining the Si wafer.

Influence of the Laser Wavelength on Harmful Effects on Granite Due to Biofilm Removal

Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 196 ◽  
Author(s):  
P. Barreiro ◽  
A. Andreotti ◽  
M. P. Colombini ◽  
P. González ◽  
J. S. Pozo-Antonio
Keyword(s):  
Yttrium Aluminum Garnet ◽  
Removal Rate ◽  
Laser System ◽  
Damage Threshold ◽  
Lower Surface ◽  
Laser Wavelength ◽  
Artistic Value ◽  
Biofilm Removal ◽  
Harmful Effects ◽  
532 Nm

The colonization of stone-built monuments by different organisms (algae, fungi, lichens, bacteria, and cyanobacteria) can lead to biodeterioration of the stone, negatively affecting the artistic value of the heritage. To address this issue, laser cleaning has been widely investigated in recent years, due to the advantages it offers over traditional mechanical and chemical methods: it is gradual, selective, contactless, and environmentally friendly. That said, the laser parameters should be optimized in order to avoid any by-effects on the surface as a result of overcleaning. However, as the adjustment of each parameter to clean polymineralic stones is a difficult task, it would be useful to know the effect of overcleaning on the different forming minerals depending on the wavelength used. In this paper, three different wavelengths (355 nm, 532 nm, and 1064 nm) of a Q-Switch neodymium-doped yttrium aluminum garnet (Nd:Y3Al5O12) laser, commonly known as QS Nd:YAG laser were applied to extract a naturally developed sub-aerial biofilm from Vilachán granite, commonly used in monuments in the Northwest (NW)Iberian Peninsula. In addition to the removal rate of the biofilm, the by-effects induced for fluences higher than the damage threshold of the stone were evaluated using stereomicroscopy, color spectrophotometry, and scanning electron microscopy with energy-dispersive x-ray spectroscopy. The results showed that different removal rates were obtained depending on the wavelength used and 532 nm obtained the highest removal level. In terms of by-effects, biotite melting was registered on all surfaces regardless of the wavelength. In addition, 532 nm seemed to be the most aggressive laser system, inducing the greatest change in appearance as a result of extracting the kaolinite crackled coating and the segregations rich in Fe, which are a result of natural weathering. These changes were translated into colorimetric changes visible to the human eye. The surfaces treated with 355 nm and 1064 nm showed lower surface changes.

An Experimental Study on Single Point Diamond Turning of an Unpolished Silicon Wafer via Micro-Laser Assisted Machining

2014 ◽  
Vol 1017 ◽  
pp. 175-180 ◽  
Author(s):  
Hossein Mohammadi ◽  
H. Bogac Poyraz ◽  
Deepak Ravindra ◽  
John A. Patten
Keyword(s):  
Single Point ◽  
High Hardness ◽  
Industrial Applications ◽  
Diamond Turning ◽  
Shear Stresses ◽  
Workpiece Material ◽  
Crystal Silicon ◽  
Laser Assisted Machining ◽  
Diamond Cutting Tool ◽  
Si Wafer

Single Pointe Diamond Turning (SPDT) of silicon can be an extremely abrasive process due to the hardness of this material. In this research SPDT is coupled with the micro-laser assisted machining (μ-LAM) technique to machine an unpolished single crystal silicon (Si) wafer. Si is increasingly being used for industrial applications as it is hard, strong, inert, light weight and has great optical and electrical properties. Manufacturing this material without causing surface and subsurface damage is extremely challenging due to its high hardness, brittle characteristics and poor machinability. However, ductile regime machining of Si is possible due to the high pressure phase transformation (HPPT) occurring in the material caused by the high compressive and shear stresses induced by the single point diamond tool tip. The μ-LAM system is used to preferentially heat and thermally soften the workpiece material in contact with a diamond cutting tool. Different outputs such as surface roughness (Ra, Rz) and depth of cuts (DoC) for different set of experiments with and without laser were analyzed. Results show that an unpolished surface of a Si wafer can be machined in two passes to get a very good surface finish.

scholarly journals Ductile behavior of optical glass in single point diamond turning

2014 ◽  
Vol 67 (2) ◽  
pp. 167-172
Author(s):  
Carlos Renato Pagotto ◽  
Jaime Gilberto Duduch ◽  
Renato Goulart Jasinevicius
Keyword(s):  
Optical Glass ◽  
Elastic Recovery ◽  
Single Point ◽  
Tool Material ◽  
Diamond Turning ◽  
Machined Surface ◽  
Force Microscopy ◽  
Semiconductor Crystals ◽  
Ductile Machining ◽  
Ductile Behavior

Single point diamond turning tests were carried out on a B270 type glass. Submicrometer cutting conditions were applied in order to generate ductile response during single point machining. The profile generated by the rapid removal of the tool tip from the machined surface, analyzed by atomic force microscopy, showed that the brittle-to-ductile transition occurs at a few tenths of micrometers. According to the machining results, the maximum feed rate capable of generating a ductile mode machining behavior is of 0.9 micrometer/revolution. Furthermore, it was shown that with the cutting depth lower than 0.100 micrometer/revolution, the material removal mechanism is totally ductile. Ribbon-like chips were not observed when ductile machining was performed, as commonly seen during ductile machining of semiconductor crystals. The chips removed had a small needle-like shape. This material's fragile behavior during machining may be related to high densification during tool/material interaction with subsequent elastic recovery response.

Improving the Surface Roughness of a CVD Coated Silicon Carbide Disk by Performing Ductile Regime Single Point Diamond Turning

2008 ◽  
Author(s):  
Deepak Ravindra ◽  
John Patten
Keyword(s):  
Surface Roughness ◽  
Silicon Carbide ◽  
Surface Quality ◽  
Removal Rate ◽  
Single Point ◽  
Extreme Environments ◽  
High Hardness ◽  
Diamond Turning ◽  
Ductile Regime Machining

Silicon carbide (SiC) is one of the advanced engineered ceramics materials designed to operate in extreme environments. One of the main reasons for the choice of this material is due to its excellent electrical, mechanical and optical properties that benefit the semiconductor, MEMS and optoelectronic industry respectively. Manufacture of this material is extremely challenging due to its high hardness, brittle characteristics and poor machinability. Severe fracture can result when trying to machine SiC due to its low fracture toughness. However, from past experience it has been proven that ductile regime machining of silicon carbide is possible. The main goal of the subject research is to improve the surface quality of a chemically vapor deposited (CVD) polycrystalline SiC material to be used in an optics device such as a mirror. Besides improving the surface roughness of the material, the research also emphasized increasing the material removal rate (MRR) and minimizing the diamond tool wear. The surface quality was improved using a Single Point Diamond Turning (SPDT) machining operation from 1158nm to 88nm (Ra) and from 8.49μm to 0.53μm (Rz; peak-to-valley).

Single Point Diamond Turning of Single Crystal Silicon Carbide: Molecular Dynamic Simulation Study

2011 ◽  
Vol 496 ◽  
pp. 150-155 ◽  
Author(s):  
Saurav Goel ◽  
Xi Chun Luo ◽  
R.L. Reuben ◽  
Waleed Bin Rashid ◽  
Ji Ning Sun
Keyword(s):  
Silicon Carbide ◽  
Single Crystal ◽  
Molecular Dynamic ◽  
Single Point ◽  
Single Crystal Silicon ◽  
Diamond Turning ◽  
Machining Process ◽  
Crystal Silicon ◽  
Molecular Dynamic Simulation Study ◽  
Machining Properties

Silicon carbide can meet the additional requirements of operation in hostile environments where conventional silicon-based electronics (limited to 623K) cannot function. However, being recent in nature, significant study is required to understand the various machining properties of silicon carbide as a work material. In this paper, a molecular dynamic (MD) simulation has been adopted, to simulate single crystal β-silicon carbide (cubic) in an ultra precision machining process known as single point diamond turning (SPDT). β-silicon carbide (cubic), similar to other materials, can also be machined in ductile regime. It was found that a high magnitude of compression in the cutting zone causes a sp3- sp2 order-disorder transition which appears to be fundamental cause of wear of diamond tool during the SPDT process.

Laser Timing Probe with Frequency Mapping for Locating Signal Maxima

2009 ◽  
Author(s):  
L.S. Koh ◽  
H. Marks ◽  
L.K. Ross ◽  
C.M. Chua ◽  
J.C.H. Phang
Keyword(s):  
Response Time ◽  
Continuous Wave ◽  
Single Point ◽  
Point Measurement ◽  
Cw Laser ◽  
Measurement Capabilities

Abstract A Laser Timing Probe (LTP) system which uses a noninvasive 1.3 µm continuous wave (CW) laser with frequency mapping and single point measurement capabilities is described. The frequency mapping modes facilitate the localization of signal maxima for subsequent single point measurements. Measurements of waveforms with long delays and 50 ps response time from NMOS and PMOS transistors are also shown.

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