Dimple Textures Research Articles

In vivo synthesis of calcium oxalate whiskers on CoCrMo alloy surfaces via biomineralization

Surface treatments using bio-technology are valuable and fascinating in the sense that such treatments are natural and yield good biocompatibility. Calcium oxalate whiskers for biomedical applications were successfully synthesized on the CoCrMo alloy surfaces implanted in Aloe leaves which consist of many active bio-chemical elements. The effect of surface wettability and surface morphology on the formation of whiskers was investigated using four differently treated CoCrMo surfaces: (i) smoothly polished surface, (ii) electrochemical etched surface, (ii) textured surface with dimples, and (iv) parallel orientated-grooved surface. Results showed that the formed whiskers had a length ranging between 100μm and 600μm, and a diameter in the range of 2μm to 5μm. Electrochemically etched surfaces had better wettability and were favorably for growing whiskers. Surface morphology with (i) dimple textures or (ii) parallel grooves facilitated the effective control of the size and amount of the grown whiskers.

804 ディンプルテクスチャ付与による銅合金の耐焼付き性向上

804 ディンプルテクスチャ付与による銅合金の耐焼付き性向上

Performance Analysis of Full-Film Textured Surfaces With Consideration of Roughness Effects

Abstract A mass-conservative algorithm that implements the Jakobsson–Floberg–Olsson cavitation theory is used to predict the performances of seal-like structures and thrust bearings with a dimpled surface texture. The results of a series of simulations for load-carrying capacity, film thickness, dimple depth, dimple density, cavitation pressure, leakage, and friction force are presented, and the relationship between these performance parameters is studied. It is shown that, under the conditions simulated, surface roughness can improve the load-carrying capacity, but its effect is limited.

Effects of surface texture size on the tribological properties of slideways

The effects of surface texture on the tribological properties of slideways were investigated experimentally. The authors designed an experimental apparatus for evaluating textured surfaces using specimens of a practical size (82 mm × 82 mm) considering the slideways used for machine tools which are one of the application fields for their research. The evaluated textures were dimple and groove textures, and their diameters and widths varied from 50 μm to 1 mm. The textures were processed by sandblasting as it is one of the alternative methods applied in industry. For comparison with the conventional textures, scraped surfaces were also evaluated. The friction coefficient and the film thickness were measured under the conditions of plane contact, and lubricating with the oil to clarify the effects of the textured pattern. The experimental results showed that the friction coefficient of the textured surfaces was smaller than that of the flat surfaces in the mixed lubrication regime. Regarding the mechanisms of friction reduction by texture types, the authors think that the dimples played the role of oil reservoir, and the parallel grooves prevented side leakage of the lubricating oil.

W1101-(3) マイクロショットピーニングのテクスチャリングへの適用可能性(【W1101】テクスチャ表面のトライボロジー,ワークショップ)

The present study described applicability of micro shot peening treatments as a tool for surface modification. The developed peening apparatus having a direct gas injection system was consisted from the double walled nozzle and the particle storage tank enclosing rubber balls and was possible to fabricate the surface texture consisted from isolated micro dimples resulted from individual particle impacts. The friction coefficient of the micro dimpled texture surface was approximately 0.003 mated with parallel grooved surface in lubricated condition. In addition, it was possible to apply oil repellence and functional gradients to the surface using mixed particles as the impact media. It was confirmed that the application of the oil repellence was effective for the decrease in the friction coefficient on higher sliding speed region and that the anti wear property of the functional gradient surface was excellent on the abrasive wear condition.

Effects of surface texture on journal-bearing characteristics under steady-state operating conditions

Developments in microscopy have a profound effect on the resurgence of tribological applications at the microscopic level. Using surfaces with controlled microgeometry may prove an effective approach to improving bearing performance. It is consequently of interest to study the lubrication of journal bearing systems taking into consideration the effect of surface geometry design. A numerical approach is used in the analysis of texture effects on bearing characteristics. The results from investigating the performance of bearing surfaces with spherical dimple textures suggest that contact characteristics such asminimumfilm thickness, maximumpressure, axial oil film flow, and friction torque may be improved through an appropriate surface texture geometry and appropriate textures distribution on the contact surface. The main purpose of our work is to model and understand the evolution of journal-bearing characteristics with textures. A rigorous methodology is recommended. The work is divided into two steps. The first one serves to quantify the evolution of the characteristics with the texture parameters and to deduce their optimized values. The second step enhance the performance of the journal bearing by progressively taking into account the optimized values of texture parameters, especially the textures disposition.

ディンプル·テクスチャの評価(第2報)

ディンプル·テクスチャの評価(第2報)

Study on Precision Planetary Milling of Spherical Dimple Texture (1st Report)

This paper presents precision planetary milling of spherical dimple texture. When the spherical dimple texture is milled using a ball end mill, form accuracy of the spherical dimple deteriorates by low cutting speed around the chisel of a ball end mill. Hence, planetary milling mechanism is proposed as an inclined spindle, which rotates a ball end mill, revolves around nomal axis (revolution axis) of a work surface. By developed mechanism, the revolution axis and the ball center of a ball end mill agrees in 1μm accuracy within ±2mm deviation. This accuracy is achieved by the principle of leverage around the gimbal joint using a pre-loaded ball bearing. A dimple texture without deterioration around a dimple center is made by the milling mechanism installed on a precision jig grinder.

Virtual Texturing: Modeling the Performance of Lubricated Contacts of Engineered Surfaces

Engineering practices and analyses have indicated that surface textures and topography may significantly affect the tribological performance of contact interfaces. Such an influence may be complicated and difficult to be captured with only a few statistic surface parameters. The need for further improvement of the performance and life of machine elements requires that surface topography and textures be optimized. The utilization of a numerical tool to determine the basic geometric aspects of surface textures may be named a virtual texturing technology, with which surface optimization may start from patterned surfaces where topography can be precisely quantified and the relationship between textures and lubrication performance can be numerically established. Presented in this paper are the concept of the virtual texturing technology, models involved, and a preliminary exploration of the relationship between a dimpled texture design and the mixed lubrication characteristics for a typical counterformal contact. The dimple influence area and the number of interruption are found to be two key factors for designing dimpled surfaces for counterformal contact lubrication. It is demonstrated that virtual texturing is able to provide comparative information and directions for innovative surface design and optimization.

111 光によるディンプルの精密測定(OS13 高機能面の形成技術)

111 光によるディンプルの精密測定(OS13 高機能面の形成技術)