Threaded Fasteners - Module 4 Fasteners Lesson 3 Notes | EduRev

: Threaded Fasteners - Module 4 Fasteners Lesson 3 Notes | EduRev

 Page 1


 
 
 
 
 
 
 
 
 
Module  
4 
Fasteners 
Version 2 ME, IIT Kharagpur 
Page 2


 
 
 
 
 
 
 
 
 
Module  
4 
Fasteners 
Version 2 ME, IIT Kharagpur 
 
 
 
 
 
 
 
 
 
Lesson  
  3 
Threaded Fasteners 
 
Version 2 ME, IIT Kharagpur 
Page 3


 
 
 
 
 
 
 
 
 
Module  
4 
Fasteners 
Version 2 ME, IIT Kharagpur 
 
 
 
 
 
 
 
 
 
Lesson  
  3 
Threaded Fasteners 
 
Version 2 ME, IIT Kharagpur 
Instructional Objectives 
 
At the end of this lesson, the students should have the knowledge of 
• Different types of bolts, screws and studs. 
• Some details of tapping and set screws. 
• Thread forms in details. 
 
4.3.1 Bolts, screws and studs are the most common types of 
threaded fasteners. They are used in both permanent or 
removable joints. 
 
Bolts: They are basically threaded fasteners normally used with nuts. 
Screws: They engage either with a preformed or a self made internal threads. 
Studs: They are externally threaded headless fasteners. One end usually meets 
a tapped component and the other with a standard nut. 
There are different forms of bolt and screw heads for a different usage. These 
include bolt heads of square, hexagonal or eye shape and screw heads of 
hexagonal, Fillister, button head, counter sunk or Phillips type. These are shown 
in figures-4.3.1.1 and 4.3.1.2. 
4.3.1.1F- Types of screw heads (Ref.[6]). 
Version 2 ME, IIT Kharagpur 
Page 4


 
 
 
 
 
 
 
 
 
Module  
4 
Fasteners 
Version 2 ME, IIT Kharagpur 
 
 
 
 
 
 
 
 
 
Lesson  
  3 
Threaded Fasteners 
 
Version 2 ME, IIT Kharagpur 
Instructional Objectives 
 
At the end of this lesson, the students should have the knowledge of 
• Different types of bolts, screws and studs. 
• Some details of tapping and set screws. 
• Thread forms in details. 
 
4.3.1 Bolts, screws and studs are the most common types of 
threaded fasteners. They are used in both permanent or 
removable joints. 
 
Bolts: They are basically threaded fasteners normally used with nuts. 
Screws: They engage either with a preformed or a self made internal threads. 
Studs: They are externally threaded headless fasteners. One end usually meets 
a tapped component and the other with a standard nut. 
There are different forms of bolt and screw heads for a different usage. These 
include bolt heads of square, hexagonal or eye shape and screw heads of 
hexagonal, Fillister, button head, counter sunk or Phillips type. These are shown 
in figures-4.3.1.1 and 4.3.1.2. 
4.3.1.1F- Types of screw heads (Ref.[6]). 
Version 2 ME, IIT Kharagpur 
 
 
 
 
 
 
 
 
 
 
 
 
 
4.3.1.2F- Types of bolt heads (Ref.[6]).. 
 
 
Tapping screws 
These are one piece fasteners which cut or form a mating thread when driven 
into a preformed hole. These allow rapid installation since nuts are not used. 
There are two types of tapping screws. They are known as thread forming 
which displaces or forms the adjacent materials and thread cutting which have 
cutting edges and chip cavities which create a mating thread. 
 
Set Screws  
These are semi permanent fasteners which hold collars, pulleys, gears etc on a 
shaft. Different heads and point styles are available. Some of them are shown in 
figure-4.3.1.3. 
 
 
 
 
Version 2 ME, IIT Kharagpur 
Page 5


 
 
 
 
 
 
 
 
 
Module  
4 
Fasteners 
Version 2 ME, IIT Kharagpur 
 
 
 
 
 
 
 
 
 
Lesson  
  3 
Threaded Fasteners 
 
Version 2 ME, IIT Kharagpur 
Instructional Objectives 
 
At the end of this lesson, the students should have the knowledge of 
• Different types of bolts, screws and studs. 
• Some details of tapping and set screws. 
• Thread forms in details. 
 
4.3.1 Bolts, screws and studs are the most common types of 
threaded fasteners. They are used in both permanent or 
removable joints. 
 
Bolts: They are basically threaded fasteners normally used with nuts. 
Screws: They engage either with a preformed or a self made internal threads. 
Studs: They are externally threaded headless fasteners. One end usually meets 
a tapped component and the other with a standard nut. 
There are different forms of bolt and screw heads for a different usage. These 
include bolt heads of square, hexagonal or eye shape and screw heads of 
hexagonal, Fillister, button head, counter sunk or Phillips type. These are shown 
in figures-4.3.1.1 and 4.3.1.2. 
4.3.1.1F- Types of screw heads (Ref.[6]). 
Version 2 ME, IIT Kharagpur 
 
 
 
 
 
 
 
 
 
 
 
 
 
4.3.1.2F- Types of bolt heads (Ref.[6]).. 
 
 
Tapping screws 
These are one piece fasteners which cut or form a mating thread when driven 
into a preformed hole. These allow rapid installation since nuts are not used. 
There are two types of tapping screws. They are known as thread forming 
which displaces or forms the adjacent materials and thread cutting which have 
cutting edges and chip cavities which create a mating thread. 
 
Set Screws  
These are semi permanent fasteners which hold collars, pulleys, gears etc on a 
shaft. Different heads and point styles are available. Some of them are shown in 
figure-4.3.1.3. 
 
 
 
 
Version 2 ME, IIT Kharagpur 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4.3.1.3F- Different types of set screws (Ref.[6]).. 
 
4.3.2  Thread forms 
Basically when a helical groove is cut or generated over a cylindrical or conical 
section, threads are formed. When a point moves parallel to the axis of a rotating 
cylinder or cone held between centers, a helix is generated. Screw threads 
formed in this way have two functions to perform in general: 
(a) To transmit power - Square. ACME, Buttress, Knuckle types of thread 
forms  are useful for this purpose. 
(b) To secure one member to another- V-threads are most useful for this 
purpose. 
Some standard forms are shown in figure-4.3.2.1 
V-threads are generally used for securing because they do not shake loose due 
to the wedging action provided by the thread. Square threads give higher 
efficiency due to a low friction. This is demonstrated in figure- 4.3.2.2. 
Version 2 ME, IIT Kharagpur 
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