Deterministic Micro Asperities on Bearings and Seals Using a Modified LIGA Process

2004 ◽  
Vol 126 (1) ◽  
pp. 147-154 ◽  
Author(s):  
L. S. Stephens ◽  
R. Siripuram ◽  
M. Hayden ◽  
B. McCartt
Keyword(s):  
Friction Coefficient ◽  
Thrust Bearing ◽  
Average Diameter ◽  
Arbitrary Cross Section ◽  
Surface Metrology ◽  
Bearing Surface ◽  
Viable Option ◽  
Manufacturing Method ◽  
Surface Areas ◽  
Manufacturing Methods

Deterministic micro asperities show potential for enhancement of lubrication in conformal contacts as found in many bearing and seal designs. Several manufacturing methods have been proposed for deterministic micro asperities. Of these, laser texturing has emerged as the most viable option. This paper proposes the LIGA MEMs manufacturing method as an alternative. Using LIGA, surfaces with patterned micron sized surface features of arbitrary cross section (cylindrical, hex, triangular, etc.) can be fabricated from electroplated nickel, gel-cast silicon nitride, or plastic. The resulting asperities can be positive (protuberances) or negative (recesses) and can have heights (depths) from 1–1000 microns and be patterned over surface areas up to about 150mm×150mm. In this paper, the LIGA method is used to fabricate a sample thrust bearing surface with a hexagonal array of positive asperities. The resulting asperities are 550 μm in average diameter, 165 μm in edge-to-edge spacing and have heights of 3–100 μm. Surface metrology indicates submicron accuracy of form and 13 nm Ra roughness on the asperity tops (land). Tribology testing in a nonpressurized oil bath indicates full film conditions and shows a 14–22% reduction in friction coefficient for a thrust surface covered with the micro asperities. A model confirms the experimental trends and indicates the potential to further reduce the friction coefficient by about 60% through optimization of the asperity geometry and layout.

Deterministic Micro Asperities on Bearings and Seals Using a Modified LIGA Process

2002 ◽  
Author(s):  
Lyndon Scott Stephens ◽  
Ravi Siripuram ◽  
Matthew Hayden ◽  
Bianca McCartt
Keyword(s):  
Friction Coefficient ◽  
Thrust Bearing ◽  
Average Diameter ◽  
Arbitrary Cross Section ◽  
Surface Metrology ◽  
Bearing Surface ◽  
Viable Option ◽  
Manufacturing Method ◽  
Surface Areas ◽  
Manufacturing Methods

Deterministic micro asperities show potential for enhancement of lubrication in conformal contacts as found in many bearing and seal designs. Several manufacturing methods have been proposed for deterministic micro asperities. Of these, laser texturing has emerged as the most viable option. This paper proposes the LIGA MEMs manufacturing method as an alternative. Using LIGA, surfaces with patterned micron sized surface features of arbitrary cross section (cylindrical, hex, triangular, etc.) can be fabricated from electroplated nickel, gel-cast silicon nitride or plastic. The resulting asperities can be positive (protuberances) or negative (recesses) and can have heights (depths) from 1–1000 microns and be patterned over surface areas up to about 150 mm × 150 mm. In this paper, the LIGA method is used to fabricate a sample thrust bearing surface with a hexagonal array of positive asperities. The resulting asperities are 550 μm in average diameter, 165 μm in edge-to-edge spacing and have heights of 3–100μm. Surface metrology indicates sub-micron accuracy of form and 13 nm Ra roughness on the asperity tops (land). Tribology testing in a non-pressurized oil bath indicates full film conditions and shows a 14–22% reduction in friction coefficient for a thrust surface covered with the micro asperities. A model confirms the experimental trends and indicates the potential to further reduce the friction coefficient by about 60% through optimization of the asperity geometry and layout.

Stresses in Oil Lubricated Bearings

1969 ◽  
Vol 184 (1) ◽  
pp. 69-82 ◽  
Author(s):  
S. M. Ibrahim ◽  
H. Mccallion
Keyword(s):  
Thrust Bearing ◽  
Journal Bearing ◽  
Fluid Pressure ◽  
Temperature Gradients ◽  
Rigid Surface ◽  
Pressure Loading ◽  
Bearing Surface ◽  
Bearing Ring ◽  
Difference Analogue ◽  
Differential Thermal Expansion

Stresses in a bimetal strip of white metal bonded to steel, to simulate a journal bearing shell or a thrust bearing ring, have been calculated for various loading conditions. The stresses arose from: fluid pressure loading on the bearing surface whilst the back was supported on a complete rigid surface; locating and holding forces, e.g. compression due to nipping-up the bearing; elastic deformation of the bearing housing; differential thermal expansion and temperature gradients, and incomplete support of the bearing shell when subjected to fluid pressure on its bearing surface. Points at which fatigue damage is likely to originate are apparent. The stresses were calculated numerically from displacements which were found, by an iterative method, to satisfy a finite difference analogue of the governing differential equations.

Static and Dynamic Characteristics of Aerostatic Circular Porous Thrust Bearings (Effect of the Shape of the Air Supply Area)

2000 ◽  
Vol 123 (3) ◽  
pp. 501-508 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kohno
Keyword(s):  
Porous Material ◽  
Dynamic Characteristics ◽  
Thrust Bearing ◽  
Aerostatic Bearing ◽  
Bearing Surface ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Porous Bearing ◽  
Air Supply ◽  
Bearing Design

Recently, graphite porous material has been used successfully in an aerostatic bearing. In actual bearing design, it is often necessary to reduce the thickness of porous material to make the bearing smaller. However, a reduction in thickness results in a reduction in the strength of the porous material. In particular, when the diameter of porous material is large, it is difficult to supply the air through the full pad area of porous material because it deforms. Therefore, in this paper, two types of air supply method (the annular groove supply and the hole supply) in a circular aerostatic porous thrust bearing are proposed to avoid the deflection of the bearing surface. The static and dynamic characteristics of aerostatic porous bearing with these air supply methods are investigated theoretically and experimentally. In addition, the effects of a surface restricted layer on the characteristics are clarified.

COMPUTATIONAL FLUID DYNAMICS SIMULATION OF EROSION-CORROSION IN ABRASIVE WATER JET MACHINING

2021 ◽  
pp. 2150031
Author(s):  
H. DENİZ ADA ◽  
MEHMET ERDEM ◽  
KADİR GOK
Keyword(s):  
High Pressure ◽  
Water Jet ◽  
Dynamics Simulation ◽  
Abrasive Water Jet ◽  
Manufacturing Method ◽  
Water Jet Cutting ◽  
Erosion Corrosion ◽  
Computer Environment ◽  
Manufacturing Methods ◽  
Traditional Manufacturing

Today, conventional machining with chip or machining without chip machining manufacturing methods is used to bring to the desired dimensions sizes the machines and equipment used in the industry. However, non-traditional manufacturing methods are used in cases where traditional machining manufacturing methods are inadequate. Cutting with water jet which is one of the non-traditional manufacturing methods is commonly used in several fields of industry. Unlike traditional manufacturing methods such as turning and milling, not using of a physical cutting tool is among the advantages of the method. Abrasive water jet manufacturing method was started to be applied by adding abrasive particles in the water jet. Apart from the superior properties of the method, possible damages occur in the water jet nozzle due to processes such as cutting or drilling by applying high pressure. Erosion-corrosion is the leading damage among these damages. In this study, the erosion-corrosion in the nozzle caused by high-pressure water and abrasive during the abrasive water jet cutting process was simulated in the computer environment. In this paper, the erosion rate in the nozzle was calculated as 6,90E-06[Formula: see text]kg/m2[Formula: see text]s. This value was converted as 0,30[Formula: see text]mm (27,09[Formula: see text]mm for yearly) via developed software for 100[Formula: see text]h.

Generative Adversarial Networks With Synthetic Training Data for Enforcing Manufacturing Constraints on Topology Optimization

2020 ◽  
Author(s):  
Michael Greminger
Keyword(s):  
Topology Optimization ◽  
Vector Space ◽  
Training Data ◽  
Generative Adversarial Networks ◽  
Manufacturing Constraints ◽  
Cnc Milling ◽  
Manufacturing Method ◽  
Latent Vector ◽  
Adversarial Networks ◽  
Manufacturing Methods

Abstract Topology optimization is a powerful tool to generate mechanical designs that use minimal mass to achieve their function. However, the designs obtained using topology optimization are often not manufacturable using a given manufacturing process. There exist some modifications to the traditional topology optimization algorithm that are able to impose manufacturing constraints for a limited set of manufacturing methods. These approaches have the drawback that they are often based on heuristics to obtain the manufacturability constraint and thus cannot be applied generally to multiple manufacturing methods. In order to create a general approach to imposing manufacturing constraints on topology optimization, generative adversarial networks (GANs) are used. GANs have the capability to produce samples from a distribution defined by training data. In this work, the GAN is trained by generating synthetic 3D voxel training data that represent the distribution of designs that can be created by a particular manufacturing method. Once trained, the GAN forms a mapping from a latent vector space to the space of manufacturable designs. The topology optimization is then performed on the latent vector space ensuring that the design obtained is manufacturable. The effectiveness of this approach is demonstrated by training a GAN on designs intended to be manufacturable on a 3-axis computer numerically controlled (CNC) milling machine.

A Short Glance on Metal 3D AM

2018 ◽  
Vol 786 ◽  
pp. 348-355
Author(s):  
Terho Iso-Junno ◽  
Kimmo Mäkelä ◽  
Kari Mäntyjärvi ◽  
Tero Jokelainen
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Future Development ◽  
Cost Efficiency ◽  
Holistic Approach ◽  
Production Method ◽  
Digital Manufacturing ◽  
Laser Melting ◽  
Manufacturing Method ◽  
Manufacturing Methods

Metal 3D AM (Additive Manufacturing) has been becoming a more common production method for larger variety of parts. In this review the current situation and future development trends of the 3D metal AM are presented, concentrating on the SLM (Selective Laser Melting) technology. A holistic approach to the AM as a digital manufacturing method is presented and different manufacturing aspects of the AM production are identified. The most promising aspects for the future development are the automatization of the AM design tasks and automatization of the production. With the development of these aspects the production and cost efficiency of the metal AM can be increased to a more competitive level compared with other manufacturing methods.

Experimental Investigation of Selective Laser Melting of Lunar Regolith for In-Situ Applications

2013 ◽  
Author(s):  
Miranda Fateri ◽  
Andreas Gebhardt ◽  
Maziar Khosravi
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Lunar Regolith ◽  
Laser Melting ◽  
Manufacturing Method ◽  
3D Objects ◽  
Scan Speed ◽  
Manufacturing Methods ◽  
Object Layer

Selective Laser Melting (SLM) is a powder based Additive manufacturing (AM) technology which builds an object layer wise using a laser beam to melt the powder on an elevated platform. Thus far numerous studies have investigated lunar manufacturing methods and construction but little is known about applicability of SLM of lunar regolith. As most lunar construction proposals require transportation of essential materials from Earth, using an in-situ manufacturing method with indigenous material would be considerably more economical. Fabrication of parts with SLM using various metals and ceramics has already been presented. As such, the feasibility of using lunar regolith mixture to create functional parts with SLM process is investigated. Variation of process parameters such as laser power, scan speed, and scan strategies is investigated and multiple 3D objects are successfully created and presented.

Preparation and Formation Mechanisms of Monodispersed Mesoporous SiO2 Microspheres by the PICA Method

2007 ◽  
Vol 280-283 ◽  
pp. 1153-1156 ◽  
Author(s):  
Li Zhao ◽  
Jia Guo Yu ◽  
Rui Guo ◽  
Bei Cheng
Keyword(s):  
Silicon Dioxide ◽  
Pore Diameter ◽  
Average Diameter ◽  
Spherical Particles ◽  
Formation Mechanisms ◽  
Average Pore ◽  
Mesoporous Silicon ◽  
Surface Areas ◽  
Sio2 Microspheres ◽  
Scanning Electron

Monodispersed mesoporous silicon dioxide microspheres were prepared by polymerization-induced colloid aggregation (PICA) method and calcined at 850oC. The prepared samples were characterized with scanning electron microscopy (SEM), thermogravimetry (TG) and BET surface areas. The results showed that the obtained SiO2 microspheres had an average diameter of about 2.0 µm, a surface area of 253.3 m2g-1, an average pore volume of 0.62 mLg-1, and an average pore diameter of 7.9 nm. The formation mechanism of SiO2 spherical particles was discussed.

scholarly journals Processing and Quality Control of Masks: A Review

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 291
Author(s):  
Sedigheh Farzaneh ◽  
Mohammadali Shirinbayan
Keyword(s):  
Quality Control ◽  
Additive Manufacturing ◽  
Human Body ◽  
Respiratory Resistance ◽  
Manufacturing Method ◽  
Different Types ◽  
Manufacturing Methods

It is clear that viruses, especially COVID-19, can cause infection and injure the human body. These viruses can transfer in different ways, such as in air transfer, which face masks can prevent and reduce. Face masks can protect humans through their filtration function. They include different types and mechanisms of filtration whose performance depends on the texture of the fabric, the latter of which is strongly related to the manufacturing method. Thus, scientists should enrich the information on mask production and quality control by applying a wide variety of tests, such as leakage, dynamic respiratory resistance (DBR), etc. In addition, the primary manufacturing methods (meltblown, spunlaid, drylaid, wetlaid and airlaid) and new additive manufacturing (AM) methods (such as FDM) should be considered. These methods are covered in this study.

scholarly journals DISTRIBUTION OF THE NORMAL REACTIONS ON THE QUANTOMOBILE WHEELS

2021 ◽  
Vol 6 (4) ◽  
pp. 72-79
Author(s):  
Jurij Kotikov ◽  
Keyword(s):  
Mathematical Model ◽  
Vacuum Energy ◽  
Thrust Bearing ◽  
Vehicle Body ◽  
Physical Vacuum ◽  
Propulsive Force ◽  
Bearing Surface ◽  
Longitudinal Stability ◽  
Analysis And Synthesis ◽  
Programming Analysis

Introduction: The progress of science has made it possible to create new quantum engines (QEs) powered by physical vacuum energy. A QE will generate a vector-based propulsive force, or thrust, applicable to the vehicle body directly, with no transmission required. Traditional cars will be upgraded with QEs and thus converted into quantomobiles. QE thrust application at the point of the vehicle body, hovering above the bearing surface, introduces changes in the traditional diagram of forces acting on the vehicle. Therefore, it is necessary to assess the influence of thrust on the longitudinal stability of the quantomobile. Methods: In the course of the study, we upgraded the diagram of forces acting on the traditional vehicle, by introducing QE thrust (bearing in mind vehicle hovering above the bearing surface). We also developed a corresponding mathematical model for the distribution of the normal reactions on the wheels, taking into account QE placement. Results: Among the developed calculation complexes to perform a qualitative analysis of the influence of force factors on the quantomobile chassis load, a complex representing the longitudinal thrust and the thrust height was distinguished. Discussion: These complexes may serve as the basis of calculation units for more detailed programming, analysis, and synthesis of the design of vehicles with QEs, assessment of the longitudinal stability of the vehicle, optimization of QE placement in the quantomobile body. Example: The method developed is presented using a quantomobile similar to a KamAZ-4326 automobile. Conclusion: The considered diagram of forces acting on a quantomobile, including QE thrust above the bearing surface, shall become generic for force diagrams of quantomobiles with additional thrusters intended to increase the longitudinal stability of the vehicle.

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