Failure Analysis Made Simple: Shafts and Fasteners

About this title

One of the benefits of understanding how to diagnose machinery failures is that the failed part tells an amazing amount about the causes. In most cases, you can look at the broken pieces and, with proper lighting, almost immediately tell what type of force is responsible. The failure will tell you the direction and the magnitude of the force, whether it was applied once or many times, and whether corrosion or wear was involved. With that knowledge of the physical mechanisms, corrective action can begin almost immediately.

This is the second in a series of Reliabilityweb.com books on mechanical equipment failure analysis. Like the previous volume, it is written as a basic text, but with the hopes that even experienced analysts will use it as a refresher and will enjoy the failure examples.

Also, like Failure Analysis Made Simple: Bearings and Gears, this book is written to help the analyst accurately understand the physical causes of the failure, so they can then find and eliminate the human and latent causes, with the ultimate goal of making their plant more reliable.

Acerca del Autor - Neville W. Sachs, P.E.

A native of Northern New Jersey, Neville W. Sachs, P.E. attended Stevens Institute of Technology in Hoboken, NJ, where he received a Bachelor of Engineering degree, majoring in Mechanical and Chemical Engineering. After a variety of manufacturing, engineering, and supervisory positions, he joined Allied Chemical (now Honeywell International). From then until the Syracuse Works closed in 1986, he was heavily involved with plant reliability, first as an engineer, then as the supervisor of the Reliability Engineering Department. While there, he was instrumental in developing one of the first large predictive maintenance inspection programs in the nation, served on a number of corporate technical committees, and received a patent for a device that demonstrates several of the mechanisms of fastener failures.

In early 1986, Mr. Sachs, a licensed Professional Engineer, joined with Philip Salvaterra to form Sachs, Salvaterra & Associates, Inc., (SS&A), a group that provided a wide range of plant reliability support services. Mr. Sachs served as the principal of SS&A until 2011 when the company was acquired by Applied Technical Services of Marietta, GA. In 2013, Mr. Sachs returned to private practice.

Mr. Sachs has conducted thousands of failure analyses and taught hundreds of failure analysis seminars across North America and Europe. He is a past chairman of the Syracuse Chapter of the ASM, and is an active member of the National Association of Corrosion Engineers, the American Society of Mechanical Engineers, National Society of Professional Engineers, and the Society of Tribologists and Lubrication Engineers (STLE). In the STLE, he was active on a national committee for many years and, in addition to being certified in several areas of nondestructive testing, his formal certifications include STLE’s “Certified Lubrication Specialist.”

He is a frequent speaker for both regional and North American pro-grams, has written the textbooks Practical Plant Failure Analysis: A Guide to Understanding Machinery Deterioration and Improving Equipment Reliability and Failure Analysis Made Simple: Bearings and Gears. He has also contributed significant sections to two other books concerning failure analysis, and has written over fifty technical articles and papers for U.S. and European magazines and journals, primarily on failure analysis and equipment reliability.

Winters are spent as a certified Ski Patroller and he and his wife, Carol Adamec, an accomplished sculptor, thoroughly enjoy skiing, tandem bicycle touring, hiking, kayaking, and chasing after ten grandchildren.

Contents

INTRODUCTION

CHAPTER 1 THE PHYSICAL CAUSES OF FAILURE AND SOME IMPORTANT DEFINITIONS
Definitions
Finding the Tensile and Yield Strengths
Fatigue Strength
Impact Strength
Corrosion Effects

CHAPTER 2 BASIC METALLURGY
Alloy Identification Systems
Hardness and Tensile Strength
The Basic Chemistry of Iron and Steel
Thermal Hardening and Heat Treating Steel
Tempering
Strain Hardening
Stress Relieving
Temperature Effects on Steel and Impact Strengths
Stress Concentrations

CHAPTER 3 RECOGNIZING FAILURE MECHANISMS
Failure Appearances
Ductile and Brittle Materials
Overload Failure Appearances
Fatigue Failures
Why Fatigue Failures Happen
How Fatigue Cracks Start and Grow
The Corrosion Mechanism
Overload Failure Examples
Ductile Failures
Brittle Failures, Brittle Fractures
Fatigue Failures
Interpreting the Progression Marks
The Shape of the IZ
Wear Failures

CHAPTER 4 FASTENERS AND FASTENER FAILURES
Common U.S. Steel Bolt Grades
Common Metric Bolt Grades
U.S. and Metric Nuts
How Bolting and Rivets Work
The Steps in the Actual Analysis
Failure Examples
Brittle Overload Failures
Ductile Overload Failures
Very Low Cycle Fatigue Failures
Low Cycle Fatigue Failures
High Cycle Fatigue Failures
Other Valuable Examples

CHAPTER 5 SHAFT FAILURES
Brittle Fractures
Ductile Overload Failures
Fatigue Failures
The Shape of the Instantaneous Zone
Torsional Fatigue Effects on Fracture Appearance
Some Projects and Some Unusual Examples
Stress Corrosion Cracking
A Detailed Failure Analysis
One Last Caution and Conclusion

REFERENCES

ABOUT THE AUTHOR