scholarly journals Parametric Influences on Heat Affected Zone in Micro-channel Milling Process of Zirconia Ceramic

2021 ◽  
Author(s):  
Omar Faruk Biswas ◽  
Abhishek Sen ◽  
Ishwer Shivakoti ◽  
Golam Kibria
Keyword(s):  
Heat Affected Zone ◽  
Laser Power ◽  
Laser System ◽  
Average Power ◽  
High Hardness ◽  
Pulse Frequency ◽  
Zirconia Ceramic ◽  
Micro Channel ◽  
Scan Speed ◽  
Haz Width

Zirconia, a bio-ceramic, is widely utilized in bioengineering, biomedical implants, dentistry, and the automotive industry due to high hardness, excellent wear resistance, etc. However, it is difficult to attain micro features on zirconia utilizing a laser machining system for the aforesaid properties. The paper deals with the study of the Heat Affected Zone (HAZ) formation during the micro-channel milling (V-shaped cross-sections) of zirconia utilizing a nanosecond fiber laser system. Experiments are accomplished to examine the consequence of control variables namely transverse feed, pulse frequency, laser power, scan number, and scan speed. The influence of each of the laser process variables on response parameter are studied in order to get the significant trends of laser parameters. With the increment of laser power, the number of pass and transverse feed, HAZ width dimensions tend to increase. The reverse phenomena are observed for pulse frequency and scan speed. The lower HAZ width which is achieved as 31.74 μm at a parametric setting of average power at 10 W, pulse frequency at 65 kHz, scanning speed at 11 mm/s, a number of pass at 1, transverse feed at 0.005 mm.

Experimental Analysis of Process and Laser Parameters in Laser Marking

2008 ◽  
Author(s):  
Jean-Pierre Kruth ◽  
Evren Yasa
Keyword(s):  
Laser Power ◽  
Pump Current ◽  
Pulse Frequency ◽  
Laser Melting ◽  
Molten Material ◽  
Chemical Methods ◽  
Laser Marking ◽  
New Process ◽  
Product Identification ◽  
Scan Speed

Laser marking is a relatively new process to produce a mark on a product by the energy of a laser beam, mostly for the purpose of product identification and traceability. Compared to other techniques such as ink-marking, mechanical engraving and electro-chemical methods, laser marking has many advantages. In this study, laser marking is done with the laser of a standard RP/RM machine, i.e. a selective laser melting machine. This makes laser marking especially suited for marking parts produced by laser RP/RM techniques. On the other hand, the major difficulty in the process is the number of parameters and their complex relations which have not yet been investigated thoroughly. In the current study, the influences of scan speed, laser pump current (laser power) and pulse frequency of a Q-switched Nd:YAG laser on the mark qualities were investigated by single-factor experiments on stainless steel parts. It was found that these parameters substantially affect mark width, depth and rim formation which is caused by the expelled molten material due to the recoil pressure during the marking process. In order to investigate the influence of cross interactions, a design of experiment methodology was used to evaluate the effects of the same parameters on the success of the laser marking process in terms of removed material and clarity of the mark (visibility, sharpness, etc.).

A Study of Fiber Laser Micro-Grooving of 316L Stainless Steel at Different Temperatures

2021 ◽  
pp. 251659842098436
Author(s):  
A. Sen ◽  
B. Doloi ◽  
B. Bhattacharyya
Keyword(s):  
Stainless Steel ◽  
Fiber Laser ◽  
Process Parameters ◽  
Laser Power ◽  
Room Temperature ◽  
316L Stainless Steel ◽  
Cutting Speed ◽  
Pulse Frequency ◽  
Different Temperatures ◽  
Haz Width

The present article deals with the generation of micro-grooves on 316L stainless steel (SS) by a nanosecond pulsed fiber laser system. Fabrication of micro-grooves on 316L SS has immensely contributed to the biomedical and automotive industries through improving the mechanical, lubrication, and corrosion resistance properties. In the present work, the considered process parameters are the preheating temperature (100°C and 200°C), along with the room temperature (24°C), cutting speed, sawing angle, pulse frequency, and laser power. The ranges of cutting speed and sawing angle are 0.1–1.1 mm s−1 and 0.1°–1°, respectively. Besides, pulse frequency and laser power vary from 55 kHz to 85 kHz and from 15 W to 45 W, respectively. The constant parameters are the pulse width of 99% and assist air pressure of 6 kgf cm−2. The variable parameters for the analysis are cut width and heat-affected zone (HAZ) width. The article aims to showcase a comprehensive study of fiber laser process parameters at different temperatures (preheated condition and room temperature) with variable sawing angles to produce better process control and bring about each considered process parameter’s critical value. The experimental results show that higher dimensions of cut width and HAZ width are observed at 200°C with the increment of sawing angle and laser power, compared to other temperatures. With the increment of cutting speed and laser power, the HAZ width tends to rise sharply. A significant drop in cut width and HAZ width dimensions is observed with the increment in pulse frequency for any temperature.

Laser Assisted High Entropy Alloy Coating on Low Carbon Steel

2019 ◽  
Vol 813 ◽  
pp. 159-164
Author(s):  
Carlos Alberto Souto ◽  
Gustavo Faria Melo da Silva ◽  
Laura Angelica Ardila Rodriguez ◽  
Aline C. de Oliveira ◽  
Kátia Regina Cardoso
Keyword(s):  
Wear Resistance ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
High Hardness ◽  
Alloy Coating ◽  
High Entropy Alloy ◽  
Nominal Composition ◽  
Low Carbon ◽  
High Entropy ◽  
Scan Speed

Coatings with high entropy alloys of the AlCoCrFeNiV system were obtained by selective laser melting on low carbon steel substrates. The effect of the variation of the Fe and V contents as well as the laser processing parameters in the development of the coating were evaluated. The coatings were obtained from the simple powder mixtures of the high purity elemental components in a planetary ball mill. The coatings were obtained by using CO2 laser with a power of 100 W, diameter of 0.16 mm, and scan speed varying from 3 to 12 mm/s. Phase constituents, microstructure and hardness were investigated by XRD, SEM, and microhardness tester, respectively. Wear resistance measurements were carried out by the micro-abrasion method using ball-cratering tests. The coatings presented good adhesion to the substrate and high hardness, of the order of 480 to 650 HV. Most homogeneous coating with nominal composition was obtained by using the higher scan speed, 12 mm/s. Vanadium addition increased hardness and gave rise to a high entropy alloy coating composed by BCC solid solutions. Ball cratering tests conducted on HEA layer showing improvement of material wear resistance, when compared to base substrate, decreasing up to 88% its wear rate, from 1.91x10-6 mm3/Nmm to 0.23x10-6 mm3/Nmm.

Laser therapy applications for osteoarthritis and chronic joint pain – A randomized placebo-controlled clinical trial

2012 ◽  
Vol 1 (4) ◽  
Author(s):  
Nelson Marquina ◽  
Roger Dumoulin-White ◽  
Arkady Mandel ◽  
Lothar Lilge
Keyword(s):  
Clinical Trial ◽  
Near Infrared ◽  
Continuous Wave ◽  
Laser System ◽  
Laser Diodes ◽  
Average Power ◽  
Evaluation Criteria ◽  
Adjunctive Treatment ◽  
Controlled Clinical Trial ◽  
Primary Evaluation

AbstractA randomized placebo-controlled clinical trial to evaluate an adjunctive treatment modality for pain associated with knee disorders was conducted utilizing a therapeutic laser system (low energy, non-surgical).The therapeutic laser system utilized a dual wavelength, multiple diode laser cluster probe with five super-pulsed 905 nm near-infrared (NIR) laser diodes, each emitting at 40 mW average power and four continuous wave 660 nm visible (VIS) red laser diodes, each emitting at 25 mW. It was used as an adjunctive modality providing 12 treatments, three times a week to a homogeneous patient population (n=126), in combination with standardized chiropractic techniques, to evaluate effectiveness on subjects presenting with osteoarthritis and knee pain. The primary endpoint was measured by the visual analog scale (VAS) to assess pain levels on a scale of 0–10. The success criteria for an individual patient in this study were identified as an improvement of 30% or more in the VAS from baseline to 12th treatment and/or an improvement of 20% or more in the VAS from baseline to 30-day follow-up evaluation.The data obtained in the study demonstrated that the present therapeutic laser system provided significant pain relief and osteoarthritic improvements in all primary evaluation criteria, with a statistical and clinical significance of

Minimization of Heat-Affected Zone Size in Welded Ultra-Fine Grained Steel under Cooling by Liquid Nitrogen during Laser Welding

2007 ◽  
Vol 539-543 ◽  
pp. 4063-4068 ◽  
Author(s):  
Hideki Hamatani ◽  
Yasunobu Miyazaki ◽  
Tadayuki Otani ◽  
Shigeru Ohkita
Keyword(s):  
Laser Welding ◽  
Liquid Nitrogen ◽  
Heat Affected Zone ◽  
Laser System ◽  
Heat Removal ◽  
Plate Temperature ◽  
Fine Grained ◽  
Laser Beam Irradiation ◽  
Average Grain Size ◽  
Plume Temperature

Ultra-fine grained steel (UFGS) with an average grain size of less than 1μm has been developed and is expected to demonstrate superior properties. However, its welded heat-affected zone, HAZ, substantially affecting the strength of a welded joint, will be easily softened after welding. Therefore, minimization of UFGS’s HAZ size during laser welding was carried out using the cooling conductor liquid nitrogen. It was found that a shielding gas with adequate flow rate for the liquid nitrogen depth was used to displace nitrogen on the area of laser beam irradiation to stabilize the weld bead. Also, because YAG laser system was mainly used because it has a lower laser induced plasma or plume temperature, which results in a decreased occurrence of pit and blowhole. HAZ size minimization strongly depends on the initial plate temperature. Reduced initial plate temperature shrinks the specific heated temperature range in which softening occurs. However, due possibly to decreasing thermal conductivity under room temperature, which prevents heat removal, the benefit of reducing the initial plate temperature is limited. The optimal initial temperature to minimize the HAZ size, in the present work, was found to be 123K.

Measurement of the Melt Pool Length During Single Scan Tracks in a Commercial Laser Powder Bed Fusion Process

2017 ◽  
Author(s):  
J. C. Heigel ◽  
B. M. Lane
Keyword(s):  
Laser Power ◽  
High Speed ◽  
Infrared Camera ◽  
Powder Bed Fusion ◽  
Single Track ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Melt Pool ◽  
Significant Difference ◽  
Scan Speed

This work presents high speed thermographic measurements of the melt pool length during single track laser scans on nickel alloy 625 substrates. Scans are made using a commercial laser powder bed fusion machine while measurements of the radiation from the surface are made using a high speed (1800 frames per second) infrared camera. The melt pool length measurement is based on the detection of the liquidus-solidus transition that is evident in the temperature profile. Seven different combinations of programmed laser power (49 W to 195 W) and scan speed (200 mm/s to 800 mm/s) are investigated and numerous replications using a variety of scan lengths (4 mm to 12 mm) are performed. Results show that the melt pool length reaches steady state within 2 mm of the start of each scan. Melt pool length increases with laser power, but its relationship with scan speed is less obvious because there is no significant difference between cases performed at the highest laser power of 195 W. Although keyholing appears to affect the anticipated trends in melt pool length, further research is required.

scholarly journals Laser power meters as an X-ray power diagnostic for LCLS-II

2018 ◽  
Vol 25 (1) ◽  
pp. 72-76 ◽  
Author(s):  
Philip Heimann ◽  
Stefan Moeller ◽  
Sergio Carbajo ◽  
Sanghoon Song ◽  
Georgi Dakovski ◽  
...  
Keyword(s):  
Free Electron Laser ◽  
Laser Power ◽  
High Vacuum ◽  
Average Power ◽  
Gas Analysis ◽  
Ultra High Vacuum ◽  
Beam Path ◽  
X Ray ◽  
High Repetition ◽  
Residual Gas

For the LCLS-II X-ray instruments, laser power meters are being developed as compact X-ray power diagnostics to operate at soft and tender X-ray photon energies. These diagnostics can be installed at various locations along an X-ray free-electron laser (FEL) beamline in order to monitor the transmission of X-ray optics along the beam path. In addition, the power meters will be used to determine the absolute X-ray power at the endstations. Here, thermopile power meters, which measure average power, and have been chosen primarily for their compatibility with the high repetition rates at LCLS-II, are evaluated. A number of characteristics in the soft X-ray range are presented including linearity, calibrations conducted with a photodiode and a gas monitor detector as well as ultra-high-vacuum compatibility tests using residual gas analysis. The application of these power meters for LCLS-II and other X-ray FEL sources is discussed.

The advancement of pump channel of high peak and high average power laser system

2018 ◽  
Author(s):  
V.V. Petrov ◽  
G.V. Kuptsov ◽  
V.A. Petrov ◽  
A.V. Laptev ◽  
A.V. Kirpichnikov ◽  
...  
Keyword(s):  
Laser System ◽  
Average Power ◽  
High Peak ◽  
High Average Power ◽  
Power Laser

scholarly journals Development of High-Peak and High-Average-Power MOPA Laser System Using Yb-Doped Photonic Crystal Fiber

2012 ◽  
Vol 40 (10) ◽  
pp. 780
Author(s):  
Hidetsugu YOSHIDA ◽  
Takeshi YAMAMURA ◽  
Masahiro ISHIKAWA ◽  
Koji TSUBAKIMOTO ◽  
Hisanori FUJITA ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Photonic Crystal Fiber ◽  
Laser System ◽  
Average Power ◽  
High Peak ◽  
High Average Power ◽  
Crystal Fiber ◽  
Mopa Laser
Sign in / Sign up

Export Citation Format

Share Document