FASTENERS - Bolts and Nut

 

FASTENERS

Fasteners

Source:Rainbowelectronics.com

    An automobile vehicle is an assembly of a large number of sub-assemblies and components. The assemblies such as engine-clutch-gearbox-differential-wheels-brakes etc. together may form a vehicle. Each of these assemblies is formed by joining many components. Some of the components or sub-assemblies can move with respect to each other, others are physically fixed together, with no relative motion possible. The first type of connection is called a kinematic joint, and the second type is called a rigid joint (or a structure). Both types of joints are important in manufacturing a vehicle, and there are many ways of achieving such joints. The process and methods used for joining depend on the type of joint, the required strength, the materials of the components being joined, the geometry of the components, and cost issues.

There are five most common methods of joining:

                    1. Mechanical fasteners

    • Screws

    • Bolts

    • Nuts and

    • Rivets

2.Welding 

3.Brazing

4.Soldering

5. Adhesive bonding.

Mechanical Fasteners

Source:Viha Steel

“ A fastener is a hardware device that mechanically joins or affixes two or more objects together”.

Automotive fasteners are the mechanical devices or components like bolts, nuts, screw, stud, rivets, shims, pin, tie rods etc. used for holding or connecting two or more objects together in a structure. Fasteners are widely used in number of industries such as aerospace, defense, automotive, petrochemical, waste processing, marine and pharmaceutical sectors.

Automotive fasteners are made up of variety of metals such as stainless steel, iron, brass, aluminum, nickel etc.

The parts or components, which need to be dismantled for repair and replacement, are joined by mechanical fasteners. For example, the main components of engine such as cylinder block, cylinder head, cylinder head cover, crank case etc; are joined by fasteners. Similarly, there are many other subassemblies which are joined by fasteners to make an engine. If the parts or sub-assemblies malfunction, can be repaired or replaced by opening the fasteners.

  

Automotive bolts/machine screws

Source:GlobalSpec

Automotive bolts often known as threaded fasteners is one of the types of auto fasteners that comprises of either a threaded pin or rod having a head at one end. The bolts are inserted through holes in assembled parts and fastened by amated nut with a help of torque. Therefore, a bolt is an externally threaded headed fastener, which is used in conjunction with a nut.

Source:SMLease design


The machine screw is an externally threaded headed fastener, which is tightened by applying torque to the head, causing it to be threaded into the material it will hold. Nearly any bolt with a common head can be used as a screw by tightening it by the head into a tapped hole. The head of machine screw does not necessarily be hex can be of different shapes. Usually, the machine screws are fully threaded.

Source: One by zero electronics
Source: Haydon Bolts

A wide variety of automotive bolts are available in the market such as connecting rod bolts, wheel bolts, hub bolts, U-bolts, J-bolts, engine mounting bolts, suspension links and bolts, lug bolts, radiator bolts, motor mount bolts and all mounting plates bolts etc. A bolt is defined either in Inch or Metric. The machine screw or bolt is described by length, the type of head and the thread.

Source:auto-fasteners.com


 The basic terms of thread

source:CNCCookbook
Source: engineering metrology


Pitch diameter: It is a theoretical diameter between the major and minor diameter of screw threads. Major diameter: It is an imaginary largest diameter of the thread which would touch the crests of an internal or external thread.

Minor diameter: It is an imaginary smallest diameter of the thread which would touch the roots of an external thread.

 Crest: Crest of the thread is the top most surface joining the two sides.

 Root: The root is the bottom of the groove between the two flanking surfaces of the thread whether internal or external.

 Flank: The flanks of a thread are the straight sides that connect the crest and the root.

 Pitch: Pitch of a thread is the distance between 2 crests.

Depth of thread: Depth of a thread is the distance between the crest and root of the thread.

Angle: The thread angle of a screw is the angle between the threads.

 

Types of bolts

Source:Youtube

 Anchor bolt Usually embedded in concrete or masonry for structural applications.

Source:Slideshare

Carriage bolt Used to fasten metal to timber, with a squared undercut to the head which holds the bolt in place once it has been tightened.


Source:Pinterest

 Elevator bolt Commonly used in conveyor systems, an elevator bolt has a flat, plain or countersunk head which holds the bolt in place when tightened. 
Source:Alibaba

Flange bolt Also known as frame bolts, this type of bolt distributes the bearing load using a washer on the undercut of the head.

Source:Grainger

Hanger bolt This type of bolt comprises two threaded ends instead of having a head, one of which contains a wood screw.

Source:Amazon

Hexagon bolt/Tap bolt A hexagon bolt comprises a head that has six sides, with threading that begins part-way down the shank, whereas a tap bolt’s shank is threaded the whole length.

Source:Alibaba

Lag bolt Also known as lag screws, this is a heavy-duty fastener that creates its own mating thread in timber and other soft materials when tightened. 

Source:Youtube

Machine bolt This type of bolt has a short shank and is intended for assembling metal components through predrilled holes.


Source:AliExpress

 Plow bolt This type of bolt is commonly used in construction tools and other devices due to its durability, and is characterized by its flat countersunk head and square shank neck.

Source:K D Fasteners

 Square head bolt This is similar to a machine bolt in that it has a short shank, in addition to a four-sided bolt head.

Source:JD Mart

 Stud bolt This type of bolt has hexagon nuts on both ends. Components are fastened between the two bolts.


Source:IndiaMART

Timber bolt Bolts that are meant for use with large timber components.

Source:Amazon.com

T-head bolt Has a T-shaped head which can be gripped by a wench and can fit into a slot with ease.

Source:Suraj Metal Corporation

Toggle bolt This type of bolt has an expanding wing-like nut which helps it to mount objects to walls.

Source:Amazon.ca


U-bolt Similar to staples, U-bolts are bent in the shape of a ‘U’ and are partially threaded on both ends.

Source:Wikipedia

Machine screw types

Source:Britanica
Source:britanica kid
Source :Boonlogistic



Assignment-Questions

Fill in the blanks

1.    A bolt is an ……………….threaded headed fastener, which is used in conjunction with a nut.

Ans: externally

2.    The machine screw is an ……………headed fastener

Ans: externally threaded

II. Answer the following

1.    What is mechanical fasteners ?

“ A fastener is a hardware device that mechanically joins or affixes two or more objects together. ex- bolts, nuts, screw, stud, rivets, shims, pin, tie rods etc

2.    List the various methods of joining process?

.Mechanical fasteners

• Screws

• Bolts

• Nuts and

• Rivets

.Welding

.Brazing

.Soldering

.Adhesive bonding.

3.    List the area which the Mechanical fasteners are widely used?

 Fasteners are widely used in number of industries such as aerospace, defence, automotive, petrochemical, waste processing, marine and pharmaceutical sectors.

4.    What is bolt?

A bolt is an externally threaded headed fastener, which is used in conjunction with a nut.

5.    List the various types of automotive bolts available in market?

    A wide variety of automotive bolts are available in the market such as         connecting rod bolts, wheel bolts, hub bolts, U-bolts, J-bolts, engine     mounting bolts, suspension links and bolts, lug bolts, radiator bolts, motor         mount bolts and all mounting plates bolts etc.

6.    Draw a neat diagram of a standard bolt and label the parts?

7.    List the various types of bolts commonly used ?

Anchor bolt Usually embedded in concrete or masonry for structural applications.

Carriage bolt Used to fasten metal to timber, with a squared undercut to the head which holds the bolt in place once it has been tightened.

 Elevator bolt Commonly used in conveyor systems, an elevator bolt has a flat, plain or countersunk head which holds the bolt in place when tightened.

Flange bolt Also known as frame bolts, this type of bolt distributes the bearing load using a washer on the undercut of the head.

Hanger bolt This type of bolt comprises two threaded ends instead of having a head, one of which contains a wood screw.

Hexagon bolt/Tap bolt A hexagon bolt comprises a head that has six sides, with threading that begins part-way down the shank, whereas a tap bolt’s shank is threaded the whole length.

Lag bolt Also known as lag screws, this is a heavy-duty fastener that creates its own mating thread in timber and other soft materials when tightened. Machine bolt This type of bolt has a short shank and is intended for assembling metal components through predrilled holes.

Plow bolt This type of bolt is commonly used in construction tools and other devices due to its durability, and is characterized by its flat countersunk head and square shank neck.

Square head bolt This is similar to a machine bolt in that it has a short shank, in addition to a four-sided bolt head.

 Stud bolt This type of bolt has hexagon nuts on both ends. Components are fastened between the two bolts.

Timber bolt Bolts that are meant for use with large timber components.

T-head bolt Has a T-shaped head which can be gripped by a wench and can fit into a slot with ease.

Toggle bolt This type of bolt has an expanding wing-like nut which helps it to mount objects to walls.

U-bolt Similar to staples, U-bolts are bent in the shape of a ‘U’ and are partially threaded on both ends






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