The Influence of Additive Chemistry on Gear Micropitting

2003 ◽  
Author(s):  
B. M. O’Connor
Keyword(s):  
Iterative Process ◽  
Surface Finishing ◽  
Test Rig ◽  
Wear Properties ◽  
Surface Asperity ◽  
Gear Design ◽  
Cylindrical Gears ◽  
Design Characteristics ◽  
Effective Component ◽  
Large Wind

Gear micropitting has been a highly visible issue in selected applications in recent years, most notably in large wind turbine transmissions. Various industry groups have addressed the problem from their own area of expertise. This has included evaluation of the gear design characteristics, surface finishing, the use of special coatings, and lubrication. A common approach to improve the lubrication has been first to increase the viscosity and create thicker films, which, in turn, reduce the amount of surface asperity interaction. Another approach from the lubricant side has been to alter the additive chemistry to effect a change in the wear properties of the system. This paper discusses the potential effects observed for different antiwear and EP chemistry on the micropitting of cylindrical gears. Tests were conducted in an FZG test rig which has been used by the industry as a guide to general gear performance. Fluids were examined in a series of experimental designs which served as the iterative process leading toward an optimized additive system. The results show that the EP, or antiscuff agent, was the most effective component at reducing the level of micropitting.

scholarly journals Scuffing of cylindrical gears with pitch line velocities up to 100 m/s

2021 ◽  
Author(s):  
J. Vorgerd ◽  
P. Tenberge ◽  
M. Joop
Keyword(s):  
Experimental Investigation ◽  
Load Capacity ◽  
Surface Condition ◽  
Damage Mechanism ◽  
Simulation Approach ◽  
Test Rig ◽  
Gear Design ◽  
Damage Location ◽  
Cylindrical Gears ◽  
Low Viscosity

AbstractIncreasing demands on the power density of gearboxes require a precisive gear design regarding common failure mechanism. Particularly in turbo gearboxes with low-viscosity lubricants, the damage mechanism scuffing is relevant. In this paper an innovative test rig for the experimental investigation of scuffing at pitch line velocities up to 100 m/s is presented. The scuffing load capacity depending on the pitch line velocity of two gear design variants running at constant temperatures and lubricant conditions was investigated. Furthermore, the morphology of scuffing was investigated with regard to the damage location and the surface condition. Based on the experimental results, a simulation approach with an accuracy superior to the existing standards for calculating the scuffing load capacity of highspeed gears has been derived.

EXPERIMENTAL STUDIES ON THE INFLUENCE OF ABRASIVE MATERIALS ON THE WEAR OF HARD-WEARING STEELS

Tribologia ◽  
2018 ◽  
Vol 281 (5) ◽  
pp. 133-141 ◽  
Author(s):  
Andrzej N. WIECZOREK
Keyword(s):  
Experimental Studies ◽  
Structural Steels ◽  
Operating Conditions ◽  
Ring Test ◽  
Test Rig ◽  
Wear Properties ◽  
Aggressive Action ◽  
Low Wear ◽  
Loss Of Mass ◽  
Wear Tests

The paper presents the wear properties of hard-wearing steels and structural steels used in mining and transport machines exposed to the aggressive action of the environment, which have been determined experimentally in the presence of diverse abrasive materials. The wear tests were carried out on a ring-on-ring test rig simulating the operating conditions of elements exposed to abrasive wear. The samples were subjected to tests in conditions of sliding contact, and the main destructive process was micro-cutting of the surface with loose corundum or quartz grain. In the case of the coal abrasive, only slight grinding in of the mating surfaces was observed. The loss of mass in the samples was measured as the parameter characterizing the wear. It was then used to determine the volume loss. Based on the results obtained, it was found that the wear resistance of hard-wearing steels was approximately four times higher as compared to S355J2 structural steel for the corundum and quartz abrasives. In the case of the coal abrasive, there was a relatively low wear for all of the materials examined.

Fractographic Evaluation of the Metallic Materials for Medical Applications

2017 ◽  
Vol 745 ◽  
pp. 62-74
Author(s):  
Brandusa Ghiban ◽  
Florentina Catalina Varlan ◽  
Marius Niculescu ◽  
Dan Voinescu
Keyword(s):  
Fracture Surface ◽  
Crack Growth ◽  
Surface Finishing ◽  
Crack Growth Behavior ◽  
Wear Properties ◽  
Engineering Structures ◽  
Macro Scale ◽  
Different Types ◽  
Cause Of Failure ◽  
Fractographic Examination

The manner of studying of the fracture modes could be done through fractography. Fractography is the study of fracture surface morphologies and it gives an insight into damage and failure mechanisms, underpinning the development of physically-based failure criteria. In composites research it provides a crucial link between predictive models and experimental observations. Fractographic methods are routinely used to determine the cause of failure in all engineering structures, especially in product failure and the practice of forensic engineering or failure analysis. In material science research, fractography is used to develop and evaluate theoretical models of crack growth behavior. One of the aims of fractographic examination is to determine the cause of failure by studying the characteristics of a fracture surface. Different types of crack growth produce characteristic features on the surface, which can be used to help identify the failure mode. The overall pattern of cracking can be more important than a single crack, however, especially in the case of brittle behavior materials. Initial fractographic examination is commonly carried out on a macro scale utilizing low power optical microscopy and oblique lighting techniques to identify the extent of cracking, possible modes and likely origins. When it is needed to identify the nature of failure, an analysis at high magnification is required and scanning electron microscopy (SEM) seems to be the best choice. The problem of fracture behavior of biometallic materials is a real one, being well and repeatedly presented in literature. Variations in alloy compositions can lead to subtle differences in mechanical, physical, or electrochemical properties. However, these differences are minor compared with the potential variability caused by differences in fabrication methodology, heat treatment, cold working, and surface finishing, where surface treatments are particularly important for corrosion and wear properties. The aim of this paper, therefore, is to summarize the different types of metals and alloys used as biomaterials, the corrosion of metals in the human body, and different failure damages of metallic implants.

Analysis of the Influence of Surface Finishing on the Performances of Dies for HPDC

2019 ◽  
Vol 285 ◽  
pp. 459-463 ◽  
Author(s):  
Federico Simone Gobber ◽  
Daniele Ugues ◽  
Mario Rosso
Keyword(s):  
Surface Roughness ◽  
Tool Steel ◽  
Die Casting ◽  
Immersion Test ◽  
Surface Finishing ◽  
Al Alloy ◽  
Test Rig ◽  
Specific Test ◽  
Die Surface ◽  
Surface Damages

The Al-alloy die casting die is a sector where the operating environment imposes a very severe aggression to hot working tools. Steel grades for such application, techniques for their surface modification and specifically conceived lubricants are continuously improved so as to limit Al soldering. Within this scenario the interaction between lubricant and die surface and the effect of finishing levels of such surface is poorly studied. This paper deals with a study of the influence of dies surface roughness on the working behavior of a die casting lubricant and on surface damages of a tool steel grade. Tool steel samples were prepared for the research and two different levels of surface roughness (as polished and as finely sand blasted) were investigated. Apart from the base characterization of steels and surface, two specific test rigs were used to study the lubricant-tool steel surface-Al alloy interactions. One of test rig was devoted to study the coupling principles of tool die surface-lubricant, while the other test rig was used to perform a cyclic immersion test in molten Al-alloy. The derived data were compared to the experimental investigation of cracks and craters as provided by cycling with a correlation with the surface finishing level of samples.

New Approach to Computerized Design of Spur and Helical Gears

2003 ◽  
Author(s):  
V. I. Goldfarb ◽  
A. A. Tkachev
Keyword(s):  
Computer Aided Design ◽  
Cutting Tool ◽  
New Approach ◽  
Helical Gears ◽  
Gear Design ◽  
Cylindrical Gears ◽  
Initial Stage ◽  
Dynamic Blocking ◽  
Aided Design ◽  
Meshing Process

The approach to the design of spur and helical cylindrical gears is being considered on the basis of application of special type geometrical objects named dynamic blocking contours (DBC) by means of which the rational choice of addendum modification coefficients (profile shift coefficients) of pinion and gearwheel is carried out. The stage of shift coefficients selection by means of DBC is singled into an independent procedure during which some gear qualities may be forecast before basic geometrical and strength calculations, that is, at the initial stage of design. Based on the concept of DBC, the computer-aided design of spur and helical gears has been developed with the practical realization of the stated design principles. In order to provide better obviousness of the design, CAD includes visualization units of meshing process of gear pair and meshing element generation by rack type cutting tool. Educational release of the developed system allows the user to master the methodology and possibilities of gear design on the basis of DBC concept and to evaluate the importance of shift coefficients selection to obtain specified properties of gears.

The General Optimization of Cylindrical Gears Including Robustness

1999 ◽  
Author(s):  
Donald R. Houser ◽  
Anthony F. Luscher ◽  
Isaias Regalado
Keyword(s):  
Sensitivity Analysis ◽  
Design Space ◽  
Robustness Analysis ◽  
Operating Conditions ◽  
Helical Gears ◽  
Optimization Criteria ◽  
Gear Design ◽  
Cylindrical Gears ◽  
Manufacturing Errors ◽  
Optimum Solution

Abstract The optimum solution for a gear design depends upon the optimization criteria used; also, the performance of the optimum may be affected due to variations in the operating conditions or the existence of manufacturing errors. In order to minimize the effects of these variations, it is necessary to perform a robustness analysis during the design process. This paper discuss the development of a procedure for the robust optimization of gears considering multiple objectives, as well as a preliminary exploration of the design space and a sensitivity analysis to manufacturing errors for a particular example of spur and helical gears.

scholarly journals Investigation of the Nominal Tooth Root Stress for External, Cylindrical Gears with Symmetric and Asymmetric Profile

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Bending Strength ◽  
Critical Cross Section ◽  
Tooth Root ◽  
Gear Design ◽  
Cylindrical Gears ◽  
Basic Issue ◽  
Root Stress

The determination of tooth bending strength is a basic issue in gear design. This work presents the change of nominal tooth root stress of external toothed, cylindrical gears depending on the geometry used. The nominal tooth root stress is analyzed with using finite element simulations. The numerical calculations are executed in Abaqus. The imported geometries are produced by our own program in MATLAB. The boundary conditions to the models are defined accordance with the most significant analytical methods used in practice. This approach allows mapping direct correlation analysis by these calculations. The optimization of computational capacity used is also considered. In addition to the examination of the significant tooth stress value of symmetrical element pairs, the position of the critical cross-section is also analyzed. The effect of the asymmetric design of the tooth profile on the nominal tooth root stress is also presented in our investigations. The purpose of the numerical simulations carried out here is to determine the effect of the coast side angle on the magnitude of the significant tooth root stress and the position of the critical cross-section.

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