This online distance learning course
will help you to
1. Understand the terminology used for threaded fasteners and bolting.
2. Understand the common modes of failures of fasteners and the possible reasons why that type of failure occurred.
3. Understand the differences between coarse and fine threads and the tolerancing of threads.
4. Understand the essential material properties of a bolt and how their strength is defined.
5. Understand the fundamental reasons why bolts are needed to be tightened.
6. Understand what is meant by joint separation or joint decompression and how to prevent it from occurring.
7. Understand torque tightening, the factors that affect the tightening torque and the scatter that is involved in the process.
8. Understand what is torque auditing, the different approaches involved and the potential issues involved.
9. Understand the causes of nuts and bolts coming loose, the effectiveness of different locking methods and how loosening can be prevented.
A training course handbook is provided
as part of the training that can be viewed online and printed
out, if required. The handbook contains background information
to the material presented on the course.
Course Agenda and Contents
Introduction to Threaded Fasteners
to modern threads - Whitworth, Sellers and metric threads.
and coarse thread and the advantages/disadvantages of each.
basic profile of Unified and metric thread forms.
tolerance positions and grades and tolerance classes.
stress area, what it is and how is it derived.
Strength of bolts
principles of bolt elongation, bolt stress and load.
tensile strength and proof load properties.
Details of common bolting specifications.
Upper and lower strength limits for bolts.
Bolt and nut head markings and identification of correct
Stainless steel fasteners ISO 3506, Duplex and Super Duplex.
Nut/bolt combinations, nut strength versus bolt strength.
Fastener Failure Modes
of the ways threaded fasteners can fail.
Manufacturing Related Quality Defects.
Design Related Quality Defects.
Failure by insufficient preload.
Fatigue failure of bolts.
Thread Stripping Failures - internal and external threads.
Bolt overload from applied forces.
Bearing stress under the bolt head or nut face.
Why bolts should be tightened
Why is tightening a bolt important?
How a preloaded joint sustains an axial load.
Joint separation – what is it and why is it important.
Why tightening bolts is important for shear loaded joints.
Explanation of why the bolt sustains a small proportion of an axial load.
Bolt stretch and joint compression.
What is meant by a tightening torque. Units used to measure torque.
Torque and bolt preload.
How torque is absorbed by a nut/bolt assembly.
The torque-tension graph.
The relationship between the tightening torque and bolt preload.
The factors which affect the torque-tension relationship.
Determining the correct tightening torque.
How to determine the appropriate tightening torque.
Tightening of the bolt head or the nut.
Scatter in the bolt preload resulting from friction variations.
Prevailing torque fasteners and how it affects the overall torque value.
Placing upper and lower limits on the torque value.
Effect on the tightening torque of flange head and countersunk fasteners.
Fundamentals of Torque Auditing
Why and when is torque auditing required?
What is meant by torque auditing?
What is meant by the terms, residual and break loose torque?
Why is the tightening torque less than the loosening torque?
The difference between torque and fastener preload.
The different torque auditing methods
The residual torque or on-torque method
The Breakloose or Off-Torque Method
The Marked Fastener Method.
The Static Audit Torque Quality Check and why it can be useful.
Issues with Torque Auditing: Joint Relaxation and Changes in the Friction Value.
Witness or Stripe Marking of Fasteners.
Why check the tightness of a bolt or nut on an assembly in service?
Self-Loosening of Threaded Fasteners
Explanation of the two main types of loosening process, relaxation and self-loosening.
The torque that is driving the loosening process.
Junker's Theory of Self-Loosening of Fasteners.
Why do Threaded Fasteners Self-Loosen?
The Junker Vibration Test Machine.
Video describing a Junker test to assess the performance of a fastener to resist self-loosening.
Loosening Curve for a Non-Locked Hexagon Headed Bolt or Nut
Loosening Curve for a Helical Spring Lock Washer.
Loosening curves for Internal and External Serrated Tooth Washers.
Loosening curves for Nylon Insert Nuts and the Wedge Lock Type of Washer.
The effectiveness of wire locking and tab washers to prevent self-loosening.
Potential fatigue failure implications of using a locking device.
What mechanism causes fasteners to become detached once loose.
Conclusions from the research and how loosening can be prevented.
Included in the training are case studies.
These case studies are drawn from various industry sectors.
Catastrophic accidents have occurred as a result of the
failure of bolted joints, they illustrate what can go wrong
when bolted joints fail and what lessons can be learned.
There is a course handbook provided as part of the training
that can be viewed online and downloaded and printed.
The course represents between 5 to 8 hours of
study (some people would complete in a shorter time, others
longer depending upon their previous experience and knowledge).
Access to the course will be available
for three months following the login and password details being
Dr Bill Eccles is a mechanical engineer
with 40 years experience in mechanical engineering with the
last 20+ years specialising in bolted joint technology and analysis.
He is a Chartered Engineer and a Fellow of the Institution of
Mechanical Engineers and has a Doctorate in Engineering on the
self-loosening of threaded fasteners.
Bill has written several articles
on bolting technology and has developed bolted joint analysis
software that is used by major organisations around the world.
Order online (using a secure server)