1. What is fastener?
A fastener is a hardware device that mechanically joins or affixes two or more objects together.
Fasteners can also be used to close a container such as a bag, a box, or an envelope; or they may involve keeping together the sides of an opening of flexible material, attaching a lid to a container, etc. Fasteners used in these manners are often temporary, in that they may be fastened and unfastened respectively.
2. Types of fastener
They may be classified into two broad categories: Removable and Permanent.
Removable Fasteners are defined as those that can be easily removed with hand tools and without damaging any parts. Ordinary nuts and bolts are typical examples.Permanent Fasteners are those that are installed so as to remain permanently in place; they would not be removed for routine maintenance work. Such as Rivets.
Semi-permanent fasteners are defined as those that can be removed with some damaging in fasteners.
3. There are some factor should be taken into account when selecting fasteners for a given application:
1. primary function
2. appearance
3. operation conditions such as vibration .loads and temperatures
4. frequency of disassembly
5. adjustability in the location of parts
6. types of materials be joined
7. consequences of failure or loosening of the fasteners
4. Threaded Fasteners
The threaded fasteners always are selected in almost all design .It is selected because of those advantages:
Ease of assembly
Ease of disassembly
Can be accomplished with relative ease by unskilled workers using minimum of special tooling and in a relatively short time.
Simple technology.
Easily inspected.
Large products can be shipped and assembled at the customer site.
Replace worn components or to make adjustments.
5.Types of Threaded Fasteners
Screws
A screw is an external threaded fastener that is generally assembled into a blind threaded hole.
Screws are by far the most common types.
screws are intended for screwing into tapped holes.
Bolt and nut
A bolt is an externally threaded fastener that is inserted through holes in the parts and screwed into a nut on the opposite side.
A nut is an internally threaded fastener having standard threads that match those on bolts of the same diameter, pitch, and thread form.
Stud and nut
A stud is threaded on both ends and is usually screwed permanently into a tapped hole.
Threads on the two ends may or may not be identical
Threaded rod and nut
A threaded rod is the least common type. It is an external threaded fastener, but without the usual head possessed by a bolt.
It is usually used when a very long threaded member is desired.
A washer is a hardware component often used with threaded fasteners to ensure tightness of the mechanical joint.
6.Thread Loosening and Thread Locking
Factors Influencing Threads Loosen:
The greater the helix angle, the greater t
