Groove Shape Optimization of Thrust Air Bearing for Small Size Spindle Considering the Processing Errors

2018 ◽  
Author(s):  
Masayuki Ochiai ◽  
Naoya Kato ◽  
Hiromu Hashimoto
Keyword(s):  
Probability Distribution ◽  
Laser Processing ◽  
Thrust Bearing ◽  
Groove Depth ◽  
Spindle Motor ◽  
Processing Method ◽  
Optimum Shape ◽  
Air Bearing ◽  
Machining Error ◽  
Processing Errors

In this research, we aim to examine the usefulness of the newly developed spindle motor proposed by Ochiai. Since machining error due to tool wear etc. used for microfabrication can be ignored, laser processing was used as a processing method. Thrust bearing grooves were generated by laser processing, and variation in groove depth was observed. Finally, the optimum shape of the thrust bearing groove was obtained by robust optimization using the probability distribution that can be approximated from the obtained machining error.

Fabrication of a Composite Coating by Laser, Nanoparticles Self-Assembly and Electrodeposition

2021 ◽  
Vol 1032 ◽  
pp. 84-90
Author(s):  
Ou Chuan Lin ◽  
Ying Luo Zhou ◽  
Jing Li ◽  
Virgil Bunyan
Keyword(s):  
Composite Coating ◽  
Self Assembly ◽  
Surface Coating ◽  
Laser Processing ◽  
Substrate Surface ◽  
Substrate Material ◽  
Processing Method ◽  
Coating Materials ◽  
Different Characteristics ◽  
Micro Morphology

In this paper, a composite micromachining process is introduced. By adjusting the surface microstructure, a composite coating with two kinds of materials with different characteristics was fabricated. Carbon steel is used as the substrate material, and laser processing is used to obtain the micro morphology on the substrate surface. nanoSiC particles were selected as one of the coating materials, and the SiC coating was added through the process of micropore induced nanoparticles self-assembly. Ni was selected as another coating material and added by electrodeposition. This processing method can be used to prepare multifunctional surface coating, combining the characteristics of different materials. This work can provide an idea to create more excellent multifunctional surfaces.

Residual heat generated during laser processing of CFRP with picosecond laser pulses

2018 ◽  
Vol 7 (3) ◽  
pp. 157-163
Author(s):  
Christian Freitag ◽  
Leon Pauly ◽  
Daniel J. Förster ◽  
Margit Wiedenmann ◽  
Rudolf Weber ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Heat Affected Zone ◽  
Laser Processing ◽  
Picosecond Laser ◽  
Theoretical Models ◽  
Laser Pulses ◽  
Groove Depth ◽  
Interaction Zone ◽  
Heat Accumulation ◽  
Residual Heat

Abstract One of the major reasons for the formation of a heat-affected zone during laser processing of carbon fiber-reinforced plastics (CFRP) with repetitive picosecond (ps) laser pulses is heat accumulation. A fraction of every laser pulse is left as what we termed residual heat in the material also after the completed ablation process and leads to a gradual temperature increase in the processed workpiece. If the time between two consecutive pulses is too short to allow for a sufficient cooling of the material in the interaction zone, the resulting temperature can finally exceed a critical temperature and lead to the formation of a heat-affected zone. This accumulation effect depends on the amount of energy per laser pulse that is left in the material as residual heat. Which fraction of the incident pulse energy is left as residual heat in the workpiece depends on the laser and process parameters, the material properties, and the geometry of the interaction zone, but the influence of the individual quantities at the present state of knowledge is not known precisely due to the lack of comprehensive theoretical models. With the present study, we, therefore, experimentally determined the amount of residual heat by means of calorimetry. We investigated the dependence of the residual heat on the fluence, the pulse overlap, and the depth of laser-generated grooves in CRFP. As expected, the residual heat was found to increase with increasing groove depth. This increase occurs due to an indirect heating of the kerf walls by the ablation plasma and the change in the absorbed laser fluence caused by the altered geometry of the generated structures.

scholarly journals Direct Laser Processing of Two-Scale Periodic Structures for Superhydrophobic Surfaces Using a Nanosecond Pulsed Laser

2020 ◽  
Vol 7 (4) ◽  
pp. 496-512 ◽  
Author(s):  
Hidenori Shimada ◽  
Shunichi Kato ◽  
Takumi Watanabe ◽  
Masaki Yamaguchi
Keyword(s):  
Contact Angle ◽  
Laser Processing ◽  
Periodic Structures ◽  
Pulsed Laser ◽  
Processing Method ◽  
Superhydrophobic Surfaces ◽  
Processing Rate ◽  
Nanosecond Pulsed Laser ◽  
Direct Laser ◽  
Micro Holes

AbstractHierarchical structures are promising geometries for superhydrophobic surfaces, however a processing method with a single laser light source that is capable of both one-pass and rapid processing has not been established. The purpose of this study was to propose a concept of direct laser processing of two-scale periodic structures exhibiting superhydrophobicity. We hypothesized that the molten material that occurs due to the expanding plasma and that is squeezed around the micro-holes could play an active role in the processing of two-scale periodic structures. Percussion drilling using a nanosecond pulsed laser (532 nm wavelength) was performed on a steel surface. Twenty four different test-pieces were prepared using pitch (16–120 μm), number of repetition shots (1–120), and fluence (2.49–20 J/cm2), as the parameters. As the results, micro-holes with bank-shaped outer rims were formed. The maximum apparent contact angle was 161.4° and the contact angle hysteresis was 4.2° for a pitch of 80 μm and 20 repetition shots. The calculated results for the apparent contact angles were consistent with the measured results. Finally, an equation for estimating the processing rate was proposed. We demonstrated that this direct processing method can achieve a maximum processing rate of 823 mm2/min.

Effects of Grooving in a Hydrostatic Circular Step Thrust Bearing With Porous Facing

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
M. Mahbubur Razzaque ◽  
M. Zakir Hossain
Keyword(s):  
Mathematical Model ◽  
Inclination Angle ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Maximum Load ◽  
Seepage Flow ◽  
Groove Depth ◽  
Small Thickness ◽  
Flow Through ◽  
High Level

Effects of grooving in a porous faced hydrostatic circular step thrust bearing are investigated using a mathematical model based on the narrow groove theory (NGT). It is shown that enhancement of load capacity by grooving the step is possible at moderate level of permeability of the porous facing. Load capacity drops sharply with the increase of porous facing thickness. However, this drop in load capacity occurs mostly within a small thickness of the porous facing. Considering the coupled effects of permeability and inertia, it is recommended that the dimensionless step location should be 0.5–0.8 and the dimensionless step height should be less than five to take advantage of grooving. The groove geometric parameters such as groove inclination angle, fraction of grooved area and groove depth corresponding to the maximum load capacity are found to be the same for both with and without porous facing. However, with porous facing, the sensitivity of the load capacity on the groove parameters reduces. At high level of permeability, the effects of grooves may become insignificant because of high seepage flow through the porous facing.

Effect of an Hourglass-Shape Tapered Sleeve on the Performance of the Fluid Dynamic Bearings of a HDD Spindle Motor

2013 ◽  
Author(s):  
J. H. Lee ◽  
M. H. Lee ◽  
G. H. Jang
Keyword(s):  
Rough Surface ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Rotating Disk ◽  
Groove Depth ◽  
Spindle Motor ◽  
Spindle System ◽  
Thrust Bearings ◽  
Steel Sleeve ◽  
Bearing Ball

Fluid dynamic bearings (FDBs) of a HDD spindle motor support the rotating disk-spindle system through the pressure generated in the fluid lubricant. The radial and axial clearances of a 2.5″ HDD spindle motor are approximately 2 and 30 micro-meters, respectively, and herringbone or spiral grooves are inscribed in the sleeve of journal or thrust bearings to provide pumping pressure. One of the difficult manufacturing processes is to inscribe uniform grooves, especially groove depth in the range of several micro meters. Grooves are inscribed on the surface of the stainless steel sleeve by the electro chemical machining (ECM) which generally generates rough surface of the sleeve in grooved bearing. Ball-sizing process is used to scrape down rough surface. When a ball passes through the sleeve of FDBs to make rough surface smooth, compressive pressure is generated between ball and sleeve inlet and between ball and sleeve outlet, respectively. It forms an hourglass-shape tapered sleeve as shown in Figure 1, and tapered sleeve generally decreases the static and dynamic performance of the FDBs and the HDD spindle system, consequently.

Holographic laser processing for three-dimensional photonic lattices

2017 ◽  
Author(s):  
Satoru Shoji ◽  
Remo Proietti Zaccaria ◽  
Satoshi Kawata
Keyword(s):  
Lattice Constant ◽  
Laser Processing ◽  
Periodic Structures ◽  
Three Dimensional ◽  
Processing Method ◽  
Direct Writing ◽  
Photosensitive Polymers ◽  
Photonic Lattices ◽  
Lattice Symmetry ◽  
Beam Technique

This article describes a holographic laser-processing method for independently controlling the lattice symmetry and lattice constant in three-dimensional photonic lattices. With this approach, optical periodicity is created in lower dimensions and three-dimensional periodicity is obtained by a combination of several lower-dimensional periodic structures. The proposed holographic laser-processing method is compared with the standard four-beam technique. Examples of experimental demonstration achieved in photosensitive polymers are given. The article also introduces a multiphoton direct-writing technique for creating defect structures in lattices towards production of defect cavity-functionalized photonic crystal devices. It shows that all Bravais lattices can be produced by choosing proper incident vectors of laser beams. The lattice constant of the structure can be changed without distorting its lattice symmetry and lattice elements.

scholarly journals Development of Method Enhanced Laser Ablation Efficiency According to Fine Curvature of the Polymer through the Preliminary Preparation Process Using UV Picosecond Laser

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 959 ◽  
Author(s):  
Seung Sik Ham ◽  
Ho Lee
Keyword(s):  
Laser Processing ◽  
Pulsed Laser ◽  
Picosecond Laser ◽  
Processing Method ◽  
New Method ◽  
Shielding Effect ◽  
Ablation Efficiency ◽  
Preliminary Preparation ◽  
Ultrashort Pulsed Laser ◽  
New Processing

In processes using the ultrashort pulsed laser, the phenomenon that the ablation efficiency is reduced due to the increase of the shielding effect of the generated plume is increasingly caused by the use of the high power and high repetition rate. A new method is needed to prevent a decrease in ablation efficiency in processing using an ultrashort pulsed laser. In this study, the proposed a processing method that can improve the ablation efficiency by providing an efficient escape path of plume, and examine the feasibility of a new processing method. The new method we proposed is a method of laser processing after generating a fine curvature in the polymer as a preliminary preparation. The fine curvature of the polymer produced by the preliminary preparation induces an artificial chimney-like opening along the path of the incident beam during laser processing, thereby enabling the plume to be effectively removed. The experiment for examine the feasibility through a new method was conducted using a 10-picosecond laser of UV wavelength with two optical systems. As a new processing method, when processing with ultrashort pulse laser, it was observed that the ablation efficiency improved.

A New Method for Processing Ceramics with Cracked Glaze

2011 ◽  
Vol 418-420 ◽  
pp. 63-66
Author(s):  
Ji Wei Fan ◽  
Xiao Peng Li ◽  
Zhao Jun Zhang ◽  
Wang Xi Zhang ◽  
Zhi Qiang Jiao ◽  
...  
Keyword(s):  
Laser Processing ◽  
Ceramic Materials ◽  
Processing Parameters ◽  
Processing Method ◽  
New Method ◽  
Ceramic Surface ◽  
Laser Technique

Laser processing ceramic materials is a new application of laser technique. This paper presents the study of making cracked glaze surface by laser processing. Proposed the applicable the composition of glaze, the main processing parameters of laser processing, and discussed the factors which may affect the quality of cracked glazing surface. It indicates that laser processing could be a new and easy processing method to produce the cracked glazing on the ceramic surface.

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