Saturday, November 17, 2018

Materials Matter

Comparing Surface Roughness Parameters

Effective gear design must account for a range of potential failure modes. As discussed in previous Materials Matter columns, gear failure modes can be...

Lambda Ratio

The lambda ratio was originally developed to quantify the quality of lubricant operating regimes relative to bearing performance . Starting around the 1990s, the...

Scuffing

Gear meshing is one of the most complex areas of study in tribology. Meshing consists of both sliding and rolling motion and can be...

Micropitting

Micropitting is a gear failure mode that typically occurs when higher contact stresses are applied to hardened gear teeth. Unlike most other failure modes,...

The Elimination of Part Break-In by Isotropic Superfinishing

Precision metallic components undergo a number of manufacturing processes that can include milling, grinding, and honing as a part of final surface preparation. A...

Automotive Fuel Efficiency Standards and the Impact from Gears

In 2010, President Obama established a course of direction for the EPA (Environmental Protection Agency) and NHTSA (National Highway Traffic Safety Administration) to set...

Wind Turbine Gear Repair

Wind turbine gearbox durability has improved significantly over the past ten years. The days of early gearbox failure due to epidemic micropitting are largely...

Power Density and Isotropic Superfinishing

Power density, also described as load-carrying capacity, is simply the amount of load that can be safely transferred by a gear or other power...

Optimizing Performance with Surface Finish and Lubrication

Materials and manufacturing processes have evolved to generate lighter, stronger, and more robust components to meet the demand for more efficient, highly loaded mechanical...

The Gear Drawing Roughness Specification

In the January Materials Matter column, “Roughness Measurement of Precision Gear Teeth,” the importance of accurate and repeatable roughness measurement of precision gear teeth...

Roughness Measurement of Precision Gear Teeth

Over the past 25 years, industries such as power generation, aerospace, automotive, and others have continuously increased the operational demands of gearboxes. The precision...

Gear Surfaces and Operational Performance

In the search for increased performance and durability, gear and bearing design has sought to make use of improved steel grades combined with enhanced...

Isotropic Superfinishing

Increasingly stringent operational requirements from customers coupled with enhanced global technical standards have heightened the focus of gear designers on a wide array of...

History of Bending Fatigue, Part VI

In the sixth and final part on the impending factors of fatigue design, we illustrate the process of Weibull failure analysis. In engineering, we...

History of Bending Fatigue Part V

In this succession of papers, we have looked at the history, failure life models, and the impending factors that contribute to bending fatigue. The...

History of Bending Fatigue, Part IV

The influence of frequency for monotonic or reversing load applications should not be underestimated. Natural frequencies must clearly be avoided. In single tooth fatigue...

History of Bending Fatigue, Part III

In rotating machinery, bending and contact fatigue life is a principle concern in design life. In all wrought and powder metal gearing and mechanical...

History of Bending Fatigue, Part II

Safety factors cannot replace appropriate evaluation of impending dynamics in fatigue design. Determining the design life model is where the process must begin. Using...

History of Bending Fatigue, Part I

Bending fatigue life is a principle concern in all wrought and powder metal gearing and all mechanical power transmission components. It is also a...

The Factor of Safety as a Statistical Design Variable

Classic Factors of safety – sometimes called service factors According to NEMA, a Motor Service Factor (SF) is the percentage of overload the motor can...
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