Investigation into LST and its Novel Application in Mould

2007 ◽  
Vol 24-25 ◽  
pp. 189-194
Author(s):  
Yun Wang ◽  
Z.Y. Xu ◽  
Y.H. Fu ◽  
Lan Cai
Keyword(s):  
Laser Beam ◽  
Material Removal ◽  
Surface Engineering ◽  
Surface Texturing ◽  
Industrial Applications ◽  
Laser Surface Texturing ◽  
Intense Laser ◽  
Full Potential ◽  
Workpiece Surface ◽  
Factors Affecting

Laser surface texturing (LST) technology that is firstly used in rollers, is a specialized surface engineering process capable of enhancing the surface material properties, wear resistance, fretting fatigue life and reducing friction. This practical technology of the LST process is based on a pulsating laser beam that, by material ablation, generates the optimum topographical surface. In order to exploit the full potential of the process, a great amount of research has explored from the material removal mechanics to the development of the LST process. This paper reports on the LST research involving the LST technology surveying process optimization, LST equipment and its industrial applications. The paper also highlights the forming theory describing the skin-pass process of transferring the textured roller’s surface structure onto the steel sheet, and the laser-matter interaction that occurs when and intense laser beam is tightly focused in the workpiece surface. It presents the influence of various factors affecting the textured workpiece performance together with the investigations into tribology of textured components. The paper also discusses these developments and some fundamental on future LST research.

scholarly journals Possibilities of Dry and Lubricated Friction Modification Enabled by Different Ultrashort Laser-Based Surface Structuring Methods

Lubricants ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 43 ◽  
Author(s):  
Stefan Rung ◽  
Kevin Bokan ◽  
Frederick Kleinwort ◽  
Simon Schwarz ◽  
Peter Simon ◽  
...  
Keyword(s):  
Laser Beam ◽  
Surface Engineering ◽  
Surface Texturing ◽  
Friction Reduction ◽  
Surface Structures ◽  
Laser Surface Texturing ◽  
Periodic Surface ◽  
The Coefficient Of Friction ◽  
Disc Configuration ◽  
Micro Structures

In this contribution we report on the possibilities of dry and lubricated friction modification introduced by different laser surface texturing methods. We compare the potential of Laser-Induced Periodic Surface Structures and Laser Beam Interference Ablation on 100Cr6 steel in a linear reciprocating ball-on-disc configuration using 100Cr6 steel and tungsten carbide balls with load forces between 50 mN and 1000 mN. For dry friction, we find a possibility to reduce the coefficient of friction and we observe a pronounced direction dependency for surfaces fabricated by Laser Beam Interference Ablation. Furthermore, Laser-Induced Periodic Surface Structures result in a load-dependent friction reduction for lubricated linear reciprocating movements. This work helps to identify the modification behaviour of laser generated micro structures with feature sizes of approximately 1 µm and reveals new possibilities for surface engineering.

Interface Evaluation of MCrAlY Powder Bond Coat on 316 SS Processed with Laser Irradiation

2014 ◽  
Vol 802 ◽  
pp. 409-414 ◽  
Author(s):  
Viviane Teleginski ◽  
Daniele C. Chagas ◽  
Luis Gustavo de Oliveira ◽  
Getúlio de Vasconcelos
Keyword(s):  
Stainless Steel ◽  
Laser Beam ◽  
Optical Microscopy ◽  
Bond Coat ◽  
Surface Texturing ◽  
Ceramic Coatings ◽  
Metallic Substrate ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
First Case

As aircraft and thermoelectric turbine blades work in aggressive environments (high temperatures and pressures), they are exposed to oxidation reactions. Ceramic coatings are employed to increase the turbine work temperature (improving its performance) and a bond coat (BC), base of particulate material of Ni-Cr-Al powders, which assure a good adhesion, gradual decrease in thermal expansion coefficient between the metallic substrate and the ceramic top coat, avoiding the oxidation effect in the metallic substrate. This research aims the study and comparison of two different deposition process routes of particulate materials of BC (MCrAlY) on AISI 316 stainless steel substrate. In the first case, the BC powder was pre-deposited by segregation method and irradiated by a CO2laser beam. In the second case, laser surface texturing was done on the stainless steel surface by a Yb: fiber laser beam, the BC was deposited by the same method, and further, irradiated by a CO2laser beam. The main focus of this work was to evaluate the resulting interface for both mentioned cases. For this propose, characterizations were made using the techniques of optical microscopy and roughness measurements. In the first case, homogenous layers of bond coat were obtained. Optical microscopy suggest the formation of a metallurgic bonding between the substrate and the MCrAlY. For the laser surface texturing, the surface roughness can be adjusted by the laser beam parameters.

scholarly journals Laser surface texturing of tool steel: textured surfaces quality evaluation

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Peter Šugár ◽  
Jana Šugárová ◽  
Martin Frnčík
Keyword(s):  
Laser Beam ◽  
Tool Steel ◽  
Surface Texturing ◽  
Scanning Speed ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Fibre Laser ◽  
Textured Surfaces ◽  
Machined Surface ◽  
Ytterbium Fibre Laser

Abstract In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

State of the Art in Laser Surface Texturing

Volume 1 ◽  
2004 ◽  
Author(s):  
Izhak Etsion
Keyword(s):  
Surface Engineering ◽  
State Of The Art ◽  
Load Capacity ◽  
Surface Texturing ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Mechanical Seals ◽  
Current Effort ◽  
Hydrodynamic Bearing ◽  
Micro Dimples

Surface texturing has emerged in the last decade as a viable option of surface engineering resulting in significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components. Various techniques can be employed for surface texturing but Laser Surface Texturing (LST) is probably the most advanced so far. LST produces a very large number of micro-dimples on the surface and each of these micro-dimples can serve either as a micro- hydrodynamic bearing in cases of full or mixed lubrication, a micro-reservoir for lubricant in cases of starved lubrication conditions, or a micro-trap for wear debris in either lubricated or dry sliding. The present paper reviews the current effort being made world wide on surface texturing in general and on laser surface texturing in particular. It presents the state of the art of LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings and thrust bearings. The paper also describes some fundamental on going research around the world with LST.

Experimental investigation for vibration reduction of surface-textured journal bearings

2019 ◽  
Vol 71 (2) ◽  
pp. 232-241 ◽  
Author(s):  
Chao Chen ◽  
Xiaojing Wang ◽  
Yifan Shen ◽  
Zhaolun Li ◽  
Jian Dong
Keyword(s):  
Friction Coefficient ◽  
Surface Texture ◽  
Surface Engineering ◽  
Dynamic Properties ◽  
Surface Texturing ◽  
Lower Surface ◽  
Journal Bearings ◽  
Laser Surface Texturing ◽  
Content Type ◽  
Micro Dimples

PurposeSurface texturing has emerged in the past two decades as a viable option of surface engineering, resulting in significant improvement in wear resistance and friction coefficient. The purpose of this study is to find the appropriate surface texture to reduce vibration and improve the stability of journal bearings.Design/methodology/approachMicro-dimples, evenly distributed in a square array, were selected as the texture pattern and formed on the lower surface of bush by the laser surface texturing technique. Experiments were carried out to evaluate the effects of micro-dimples under different depths, densities and distributions.FindingsThe results are summarized in the form of shaft center orbits, waterfall illustrations and Hilbert-Huang transforms. In the entire test, it was found that an optimum geometric and distributive range of micro-dimples exists, where vibration acceleration can be decreased at least 3dB and stability can be greatly improved.Originality/valueA majority of researchers devoted to studying on static characteristics, such as friction coefficient, load carrying capacity, pressure distribution and cavitation model. Besides, the influence of surface texture on stability of rotor-journal bearing system was rarely investigated and the recent examples can be found in Refs. (Ausas et al. 2007). However, a complete study of textured journal bearings has not been undertaken in the dynamic properties. Therefore, the purpose of this paper is to experimentally investigate the comprehensive effects of density, depth and distribution of micro-dimples on bearing vibration and stability.

scholarly journals Laser Processing of Hard and Ultra-Hard Materials for Micro-Machining and Surface Engineering Applications

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 895
Author(s):  
Kafayat Eniola Hazzan ◽  
Manuela Pacella ◽  
Tian Long See
Keyword(s):  
Surface Engineering ◽  
Surface Texturing ◽  
Solid Lubricants ◽  
Laser Surface Texturing ◽  
Feed Speed ◽  
Primary Role ◽  
Tungsten Carbides ◽  
Wear Properties ◽  
Workpiece Material ◽  
Hard Materials

Polycrystalline diamonds, polycrystalline cubic boron nitrides and tungsten carbides are considered difficult to process due to their superior mechanical (hardness, toughness) and wear properties. This paper aims to review the recent progress in the use of lasers to texture hard and ultra-hard materials to a high and reproducible quality. The effect of wavelength, beam type, pulse duration, fluence, and scanning speed is extensively reviewed, and the resulting laser mechanisms, induced damage, surface integrity, and existing challenges discussed. The cutting performance of different textures in real applications is examined, and the key influence of texture size, texture geometry, area ratio, area density, orientation, and solid lubricants is highlighted. Pulsed laser ablation (PLA) is an established method for surface texturing. Defects include melt debris, unwanted allotropic phase transitions, recast layer, porosity, and cracking, leading to non-uniform mechanical properties and surface roughness in fabricated textures. An evaluation of the main laser parameters indicates that shorter pulse durations (ns—fs), fluences greater than the ablation threshold, and optimised multi-pass scanning speeds can deliver sufficient energy to create textures to the required depth and profile with minimal defects. Surface texturing improves the tribological performance of cutting tools in dry conditions, reducing coefficient of friction (COF), cutting forces, wear, machining temperature, and adhesion. It is evident that cutting conditions (feed speed, workpiece material) have a primary role in the performance of textured tools. The identified gaps in laser surface texturing and texture performance are detailed to provide future trends and research directions in the field.

Effects of the Laser Beam Interaction with the Workpiece Material

2012 ◽  
Vol 504-506 ◽  
pp. 1207-1212
Author(s):  
Margareta Coteaţă ◽  
Laurenţiu Slătineanu ◽  
Irina Grigoraş (Beşliu) ◽  
Nicolae Pop
Keyword(s):  
Laser Beam ◽  
Material Removal ◽  
Machining Parameters ◽  
Workpiece Material ◽  
Laser Beam Machining ◽  
Workpiece Surface ◽  
Physical Effects ◽  
Beam Interaction ◽  
The Impact ◽  
Experimental Researches

The laser beam machining uses the effects generated at the impact of the workpiece surface with a laser beam that has adequate energetically and spatial - temporal characteristics. It is known that, as result of the laser beam impact with the workpiece material, local chemical and physical effects are signalized. In order to study such effects and simultaneously the technological possibilities of laser beam equipment, some experimental researches were developed on an Ytterbium fiber laser equipment of 300 W. Movements of the laser spot along established trajectories were ensured, changing the sizes of the machining parameters. The influence exerted by the machining parameters and by the materials characteristics on the material removal from the test piece was highlighted. The surface layer modifications were also studied.

Influence of the Cross-Hatched Surface Texture on a Starved Hydrodynamic Linear Contact

2007 ◽  
Author(s):  
M. Organisciak ◽  
G. Cavallaro ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Surface Texturing ◽  
Cylinder Liner ◽  
Industrial Applications ◽  
Laser Surface Texturing ◽  
Surface Pattern ◽  
Oil Consumption ◽  
Transient Model ◽  
The Cross ◽  
Deterministic Description

Surface roughness and topography are two important parameters that influence the film thickness and friction of a lubricated contact. In many industrial applications, these parameters are imposed by the manufacturing process. This has been the case for the cylinder liner: the honing process creates a specific cross-hatched groove pattern on the cylinder liner surface. Laser surface texturing can produce surfaces with the same type of micro-geometry, but with an increased precision and control. Thus a better compromise between friction losses and oil consumption can be found. For this, it is necessary to understand the effects of the cross-hatched grooves on the film thickness and friction. This paper describes a transient model of a starved hydrodynamic linear contact based on the Reynolds equation. A deterministic description of the surface cross-hatched grooves is used. The results show that the introduction of a surface pattern always reduces the mean film thickness compared to a smooth surface. This reduction depends on parameters like cross-hatch angle and groove density. An appropriate cross-hatched angle can reduce the frictional losses.

State of the Art in Laser Surface Texturing

2005 ◽  
Vol 127 (1) ◽  
pp. 248-253 ◽  
Author(s):  
Izhak Etsion
Keyword(s):  
Surface Engineering ◽  
State Of The Art ◽  
Load Capacity ◽  
Surface Texturing ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Mechanical Seals ◽  
Current Effort ◽  
Hydrodynamic Bearing ◽  
Micro Dimples

Surface texturing has emerged in the last decade as a viable option of surface engineering resulting in significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components. Various techniques can be employed for surface texturing but Laser Surface Texturing (LST) is probably the most advanced so far. LST produces a very large number of micro-dimples on the surface and each of these micro-dimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication, a micro-reservoir for lubricant in cases of starved lubrication conditions, or a micro-trap for wear debris in either lubricated or dry sliding. The present paper reviews the current effort being made world wide on surface texturing in general and on laser surface texturing in particular. It presents the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings and thrust bearings. The paper also describes some fundamental on going research around the world with LST.

scholarly journals Fast laser surface texturing of spherical samples to improve the frictional performance of elasto-hydrodynamic lubricated contacts

Friction ◽  
2021 ◽  
Author(s):  
G. Boidi ◽  
P. G. Grützmacher ◽  
A. Kadiric ◽  
F. J. Profito ◽  
I. F. Machado ◽  
...  
Keyword(s):  
Surface Texturing ◽  
Hydrodynamic Pressure ◽  
Friction Reduction ◽  
Laser Surface Texturing ◽  
Textured Surfaces ◽  
Engineering Applications ◽  
Lubricated Contacts ◽  
Fluid Uptake ◽  
Direct Laser ◽  
Frictional Performance

AbstractTextured surfaces offer the potential to promote friction and wear reduction by increasing the hydrodynamic pressure, fluid uptake, or acting as oil or debris reservoirs. However, texturing techniques often require additional manufacturing steps and costs, thus frequently being not economically feasible for real engineering applications. This experimental study aims at applying a fast laser texturing technique on curved surfaces for obtaining superior tribological performances. A femtosecond pulsed laser (Ti:Sapphire) and direct laser interference patterning (with a solid-state Nd:YAG laser) were used for manufacturing dimple and groove patterns on curved steel surfaces (ball samples). Tribological tests were carried out under elasto-hydrodynamic lubricated contact conditions varying slide-roll ratio using a ball-on-disk configuration. Furthermore, a specific interferometry technique for rough surfaces was used to measure the film thickness of smooth and textured surfaces. Smooth steel samples were used to obtain data for the reference surface. The results showed that dimples promoted friction reduction (up to 20%) compared to the reference smooth specimens, whereas grooves generally caused less beneficial or detrimental effects. In addition, dimples promoted the formation of full film lubrication conditions at lower speeds. This study demonstrates how fast texturing techniques could potentially be used for improving the tribological performance of bearings as well as other mechanical components utilised in several engineering applications.

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