June 2010

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Feature Articles

At the PEEK of the Polymer Food Chain
In the hypercompetitive race to increase automobile efficiency, Metaldyne has been developing its balance shaft module line with Victrex PEEK polymer in place of metal gears. The collaborative product development resulted in significant reductions in inertia, weight and power consumption, as well as improvement in noise, vibration and harshness (NVH) performance.

Getting Wired into EDM
Technology emphasizes high accuracies and improved surface finishes.

Single-Pass Honing Holds the Line on PM Sprockets
Bore finishing system from Sunnen helps Cloyes Gear and Products achieve high accuracy, productivity and process capability.

Hard Turning Large-Diameter Parts
Fuji's VTP-1000 is designed for highly accurate fine finishing of cylindrical components up to one meter in diameter.

Technical Articles

Bending Fatigue, Impact and Pitting Resistance of Ausform-Finished PM Gears
The powder metal (P/M) process is making inroads in automotive transmission applications due to substantially lower costs of P/M-steel components for high-volume production, as compared to wrought or forged steel parts. Although P/M gears are increasingly used in powered hand tools, gear pumps and as accessory components in automotive transmissions, P/M-steel gears are currently in limited use in vehicle transmission applications. The primary objective of this project was to develop high-strength P/M-steel gears with bending fatigue, impact resistance and pitting fatigue performance equivalent to current wrought steel gears.

Variation Analysis of Tooth Engagement and Load Sharing in Involute Splines
Involute spline couplings are used to transmit torque from a shaft to a gear hub or other rotating component. External gear teeth on the shaft engage an equal number of internal teeth in the hub. Because multiple teeth engage simultaneously, they can transmit much larger torques than a simple key and keyway assembly. However, manufacturing variations affect the clearance between each pair of mating teeth, resulting in only partial engagement.

The Anatomy of a Micropitting-Induced Tooth Fracture Failure
Micropitting has become a major concern in certain classes of industrial gear applications, especially wind power and other relatively highly loaded, somewhat slow-speed applications, where carburized gears are used to facilitate maximum load capacity in a compact package. While by itself the appearance of micropitting does not generally cause much perturbation in the overall operation of a gear system, the ultimate consequences of a micropitting failure can, and frequently are, much more catastrophic.


Summertime...and the Statistics Are Easy (Publishers Page)
With this change of seasons seems to have come a change in mood as well. Manufacturers are optimistic.

Letter to the Editor (Voices)
Reader's response to a previous issue.

Faster Honing to Mirror Fishises on Gear Faces and Bores (Product News)
Stringent NVH requirements, higher loads and the trend towards miniaturization to save weight and space are forcing transmission gear designers to increasingly tighten the surface finish, bore size and bore-to-face perpendicularity tolerances on the bores of transmission gears.

Product News (Product News)
The complete Product News section from the June 2010 issue of Gear Technology.

Gear Applications All the Rage at Windpower 2010 (Events)
Capitalizing on a burgeoning new technology where gears are of great import, the gear community gathered en masse at the American Wind Energy Association’s Windpower Expo 2010.

Technical Calendar (Events)
The complete Technical Calendar from the June 2010 issue of Gear Technology.

Industry News (Industry News)
The complete Industry News section from the June 2010 issue of Gear Technology.

Weird Science (Addendum)
Who knew what a few hundred bacteria could do with a little cooperation? Andrey Sokolov of Princeton University, Igor Aronson from the Argonne National Laboratory and Bartosz Grzybowski and Mario Apodaca from Northwestern University found out after placing microgears (380 microns long with slanted spokes) in a solution with the common aerobic bacteria Bacillus subtilis. The scientists observed that the bacteria appeared to swim randomly but occasionally collided with the spokes of the gears and turned them.