Page 12 - Cam Design Handbook

THBPR 9/19/03 7:30 PM Page x

x PREFACE

Furthermore, this book contains the latest, most important techniques and test data
available. The philosophy of the book is to present diversified applications for cams to aid
the reader’s understanding and design selection. This volume also contains many new
examples, a listing of computer software, and an extensive list of references.
It should be noted that cams, gearing, rolling-element bearings, and traction (friction)
drives are of the same basic mechanical family, the study of which is generically referred
to as contact mechanics. These devices have in common rolling and/or sliding action
coupled with reasonably high concentrated contact (Hertz) stresses. In the field of contact
mechanics the failure mechanisms among these machine elements are similar and are
related to material metallurgy and heat treatment, lubricant rheology and chemistry, surface
topography and geometry, and applied contact load (stress). These machine components
also have commonly related manufacturing requirements. Hence, they share a similar
manufacturing technology and engineering analysis.
The significance of cam profile accuracy is emphasized. A surface may appear smooth
to the eye and yet have poor dynamic properties. Depending on the application and loads
the cam profile accuracy and its surface finish may affect the life, vibration, and noise of
a cam-follower system. Poor manufacturing techniques can impede the functional ability
of a mechanism or machine. Also, the choice of a lubricant and the lubrication system is
pertinent on all designs.
We express our respect for the inventors, designers, engineers, scientists, toolmakers,
and machinists who produced cam systems in the past. Our knowledge and experience are
a result of the amazing contributions and successful machines these experts handed down
over the years that they toiled. This evidence of their work is our fortunate heritage. We
are surrounded with evidence of the high-quality performance of these machines, which
was accomplished with less mathematical guidance, poor manufacturing facilities, and
crude measurement tools. All the while, nature revealed her secrets, very slowly, bit by
bit. It is to be noted that the Chinese exercise for health and combat, T’ai Chi Ch’uan, has
a ritual that spiritually parallels the foregoing thought. The training performance classes
conclude with the loud clapping of hands, which is speculated to be in deference to all
those who went before.
Last, I wish to express my appreciation to Heather Tinsley, Washington, D.C., who
edited and assisted in the production of this handbook. Also, grateful acknowledgment is
due the elite chapter contributors whose dedication to the handbook is most noteworthy.
I wish also to thank the many in academia and industry who were helpful in providing
valuable guidance and information for the book, such as Samuel L. Doughty, Consulting
Engineer, Mount Ephraim, New Jersey; Arthur F. Erdman, Professor of Mechanical Engi-
neering, University of Minnesota, Minneapolis; Ralph Fusco, Consulting Engineer,
Commack, New York; Grigor Kerdanyan, Consulting Engineer, Van Nuys, California;
James A. Kurth, Senior Analytical Engineer, Commercial Cam Company, Inc., Wheeling,
Illinois; Bernard Roth, Professor of Mechanical Engineering, Stanford University, Palo
Alto, California; Michael Savage, Professor Emeritus of Mechanical Engineering, Uni-
versity of Akron, Akron, Ohio; and James L. Wiederrich, Manager, Modeling and Simu-
lation, United Defense L.P., Santa Clara, California. Special recognition goes to Erwin V.
Zaretsky, Branch Chief of Mechanical Components Branch, NASA Lewis Research
Center, Cleveland, Ohio, for the many inspirational hours we spent discussing the subject
of cams.

Harold A. Rothbart