scholarly journals Discussion: “The Effects of Artificially-Produced Defects on the Film Thickness Distribution in Sliding EHD Point Contacts” (Cusano, C., and Wedeven, L. D., 1982, ASME J. Lubr. Technol., 104, pp. 365–375)

1982 ◽  
Vol 104 (3) ◽  
pp. 375-375
Author(s):  
W. O. Winer
Keyword(s):  
Film Thickness ◽  
Thickness Distribution ◽  
Point Contacts

scholarly journals The Effects of Artificially-Produced Defects on the Film Thickness Distribution in Sliding EHD Point Contacts

1982 ◽  
Vol 104 (3) ◽  
pp. 365-375 ◽  
Author(s):  
C. Cusano ◽  
L. D. Wedeven
Keyword(s):  
Film Thickness ◽  
Contact Region ◽  
Thickness Distribution ◽  
Point Contact ◽  
Optical Interferometry ◽  
Point Contacts ◽  
Thickness Profile ◽  
Inlet Region

The effects of artificially-produced dents and grooves on the elastohydrodynamic (EHD) film thickness profile in a sliding point contact are investigated by means of optical interferometry. The defects, formed on the surface of a highly polished ball, are held stationary at various locations within and in the vicinity of the contact region while the disk is rotating. It is shown that the defects, having a geometry similar to what can be expected in practice, can dramatically change the film thickness which exists when no defects are present in or near the contact. This change in film thickness is mainly a function of the position of the defects in the inlet region, the geometry of the defects, the orientation of the defects in the case of grooves, and the depth of the defect relative to the central film thickness.

Film Thickness in Starved EHL Point Contacts

1998 ◽  
Vol 120 (1) ◽  
pp. 126-133 ◽  
Author(s):  
F. Chevalier ◽  
A. A. Lubrecht ◽  
P. M. E. Cann ◽  
F. Colin ◽  
G. Dalmaz
Keyword(s):  
Film Thickness ◽  
Numerical Study ◽  
Thickness Distribution ◽  
Experimental Studies ◽  
Thickness Reduction ◽  
Complete Analysis ◽  
Point Contacts ◽  
Governing Parameter ◽  
Experimental Findings ◽  
Side Flow

This paper presents a numerical study of the effects of inlet supply starvation on film thickness in EHL point contacts. Generally this problem is treated using the position of the inlet meniscus as the governing parameter; however, it is difficult to measure this in real applications. Thus, in this paper an alternative approach is adopted whereby the amount of oil present on the surfaces is used to define the degree of starvation. It is this property which determines both meniscus position and film thickness reduction. The effect of subsequent overrollings on film thickness decay can also be evaluated. In the simplest case a constant lubricant inlet film thickness in the Y direction is assumed and the film thickness distribution is computed as a function of the oil available. This yields an equation predicting the film thickness reduction, with respect to the fully flooded value, from the amount of lubricant initially available on the surface, as a function of the number of overrollings n. However, the constant inlet film thickness does not give a realistic description of starvation for all conditions. Some experimental studies show that the combination of side flow and replenishment action can generate large differences in local oil supply and that the side reservoirs play an important role in this replenishment mechanism. Thus the contact centre can be fully starved whilst the contact sides remain well lubricated. In these cases, a complete analysis with a realistic inlet distribution has been carried out and the numerical results agree well with experimental findings.

scholarly journals Controlling Film Thickness Distribution by Magnetron Sputtering with Rotation and Revolution

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 599
Author(s):  
Handan Huang ◽  
Li Jiang ◽  
Yiyun Yao ◽  
Zhong Zhang ◽  
Zhanshan Wang ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Film Thickness ◽  
Multilayer Film ◽  
Thickness Distribution ◽  
Parabolic Cylinder ◽  
Particle Model ◽  
Planetary Motion ◽  
X Rays ◽  
X Ray ◽  
Sputtering System

The laterally graded multilayer collimator is a vital part of a high-precision diffractometer. It is applied as condensing reflectors to convert divergent X-rays from laboratory X-ray sources into a parallel beam. The thickness of the multilayer film varies with the angle of incidence to guarantee every position on the mirror satisfies the Bragg reflection. In principle, the accuracy of the parameters of the sputtering conditions is essential for achieving a reliable result. In this paper, we proposed a precise method for the fabrication of the laterally graded multilayer based on a planetary motion magnetron sputtering system for film thickness control. This method uses the fast and slow particle model to obtain the particle transport process, and then combines it with the planetary motion magnetron sputtering system to establish the film thickness distribution model. Moreover, the parameters of the sputtering conditions in the model are derived from experimental inversion to improve accuracy. The revolution and rotation of the substrate holder during the final deposition process are achieved by the speed curve calculated according to the model. Measurement results from the X-ray reflection test (XRR) show that the thickness error of the laterally graded multilayer film, coated on a parabolic cylinder Si substrate, is less than 1%, demonstrating the effectiveness of the optimized method for obtaining accurate film thickness distribution.

scholarly journals A thermal resistances-based approach for thermal-elastohydrodynamic calculations in point contacts

2017 ◽  
Vol 232 (11) ◽  
pp. 2088-2102 ◽  
Author(s):  
Eduardo de la Guerra Ochoa ◽  
Javier Echávarri Otero ◽  
Enrique Chacón Tanarro ◽  
Benito del Río López
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thermal Effects ◽  
Good Accuracy ◽  
Computational Cost ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
New Approach ◽  
Ball On Disc

This article presents a thermal resistances-based approach for solving the thermal-elastohydrodynamic lubrication problem in point contact, taking the lubricant rheology into account. The friction coefficient in the contact is estimated, along with the distribution of both film thickness and temperature. A commercial tribometer is used in order to measure the friction coefficient at a ball-on-disc point contact lubricated with a polyalphaolefin base. These data and other experimental results available in the bibliography are compared to those obtained by using the proposed methodology, and thermal effects are analysed. The new approach shows good accuracy for predicting the friction coefficient and requires less computational cost than full thermal-elastohydrodynamic simulations.

An Accurate Solution of the Gas Lubricated, Flat Sector Thrust Bearing

1977 ◽  
Vol 99 (1) ◽  
pp. 82-88 ◽  
Author(s):  
I. Etsion ◽  
D. P. Fleming
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Thickness Distribution ◽  
Maximum Load ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Thrust Bearings ◽  
Practical Design ◽  
Minimum Film Thickness

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Effects of out-of-contact lubricant channeling on friction and film thickness in starved elastohydrodynamic lubrication point contacts

2016 ◽  
Vol 231 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Fadi Ali ◽  
Ivan Křupka ◽  
Martin Hartl
Keyword(s):  
Film Thickness ◽  
Digital Camera ◽  
Elastohydrodynamic Lubrication ◽  
Contact Condition ◽  
Friction Reduction ◽  
Rolling Element Bearings ◽  
Point Contacts ◽  
Practical Applications ◽  
Rolling Element ◽  
Ball On Disc

This study presents experimental results on the effect of out-of-contact lubricant channeling on the tribological performance of nonconformal contacts under starved lubrication. Channeling of lubricant was carried out by adding a slider with a limited slot for scraping the displaced lubricant on one of mating surfaces (ball). Thus, the scraped lubricant is forced to flow back into the depleted track through the limited slot resulting in robust replenishment. The measurements have been conducted using optical tribometer (ball-on-disc) equipped with a digital camera and torque sensor. The effect of lubricant channeling was compared to the original contact condition by means of measuring friction and film thickness. The results show that the out-of-contact lubricant channeling leads to a significant enhancement of film thickness and friction reduction under starved conditions. Indeed, the starved elastohydrodynamic lubrication contacts transformed to the fully flooded regime after introducing the flow reconditioning. Moreover, the film thickness decay over time, which is common with starved elastohydrodynamic lubrication contacts, has not been observed in the case of lubricant channeling. However, the beneficial effect of lubricant channeling diminishes as the original contact condition tends to the fully flooded regime. The results of this study can be easily implemented in practical applications such as radial and thrust rolling-element bearings.

Influence of substrate movement on the ITO film thickness distribution during magnetron sputtering

2017 ◽  
Vol 35 (6) ◽  
pp. 061301 ◽  
Author(s):  
Ivan A. Starkov ◽  
Ilya A. Nyapshaev ◽  
Alexander S. Starkov ◽  
Sergey N. Abolmasov ◽  
Alexey S. Abramov ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Film Thickness ◽  
Thickness Distribution ◽  
Ito Film ◽  
Influence Of Substrate
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