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January/February 2002

Archive > 2002 > January/February 2002

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Feature Articles

Technology Tidbits
New Technique for Forging Crowned Helical Gears Createch Co. Ltd., a forging die manufacturer from Shizuoka, Japan, has developed a net-shape cold-forging process for forming helical gears and splines with crowned teeth.

Technical Articles

Net-Shape Forged Gears - The State of the Art
Traditionally, high-quality gears are cut to shape from forged blanks. Great accuracy can be obtained through shaving and grinding of tooth forms, enhancing the power capacity, life and quietness of geared power transmissions. In the 1950s, a process was developed for forging gears with teeth that requires little or no metal to be removed to achieve final geometry. The initial process development was undertaken in Germany for the manufacture of bevel gears for automobile differentials and was stimulated by the lack of available gear cutting equipment at that time. Later attention has turned to the forging of spur and helical gears, which are more difficult to form due to the radial disposition of their teeth compared with bevel gears. The main driver of these developments, in common with most component manufacturing, is cost. Forming gears rather than cutting them results in increased yield from raw material and also can increase productivity. Forging gears is therefore of greater advantage for large batch quantities, such as required by the automotive industry.

Consideration of Moving Tooth Load in Gear Crack Propagation Predictions
Effective gear designs balance strength, durability, reliability, size, weight, and cost. Even effective designs, however, can have the possibility of gear cracks due to fatigue. In addition, truly robust designs consider not only crack initiation, but also crack propagation trajectories. As an example, crack trajectories that propagate through the gear tooth are the preferred mode of failure compared to propagation through the gear rim. Rim failure will lead to catastrophic events and should be avoided. Analysis tools that predict crack propagation paths can be a valuable aid to the designer to prevent such catastrophic failures.

Failure Mechanisms in Plastic Gears
Plastics as gear materials represent an interesting development for gearing because they offer high strength-to-weight ratios, ease of manufacture and excellent tribological properties (Refs. 1-7). In particular, there is a sound prospect that plastic gears can be applied for power transmission of up to 10 kW (Ref. 6).

Departments

Cyber-Seminars: A Virtual Success (Publishers Page)
You hardly have to leave your office anymore, because the whole world is being piped right to your desktop. I know, because I recently attended my first seminar by Internet.

The Gear Analysis Handbook by James L. Taylor Vibration Consultants Inc. (Voices)
The author has written this book primarily from the viewpoint of analyzing vibrations on heavy industrial and mill gearing that may have been in service for a prolonged time. The purpose is to diagnose problems, especially the source or cause of failure. However, the principles and analysis techniques can be used for all types and sizes of gears, as well as for gear noise analysis.

Returning the Personal Touch to Business (Voices)
Current Letter To The Editor for January/February 2002.

Product News (Product News)
Complete Product News for January/February 2002.

Revolutions (Revolutions)
Welcome to Revolutions, the column that brings you the latest, most up-to-date and easy-to-read information about the people and technology of the gear industry.

Technical Calendar (Events)
Completer Technical Calendar for January/February 2002.

Industry News (Industry News)
Complete Industry News for January/February 2002.

Addemdum (Addendum)
Find the gear-related words listed on the right in the puzzle below. The words may be horizontal, vertical or diagonal and may be written forward or backward.