WASHERS-TYPES AND USES
.purpose of washers
. the type of washers
. uses of each type of washers
Purpose
It is a common practice to provide washers under the nuts in bolted joints.
Washers help to
Increse the frictional grip
Prevent loosening of nuts due to vibrations
Prevent damage to the workpiece and distribute force over a larger area.
Types of washers
There are different types of washers available. They are
Plain of flat washers
Taper washers
Spring washers
Tab washers
Toothed lock washers
Plain or flat washers
These washers are used for bolting assemblies with flat surfaces. The diameter, thickness and the bore diameter are proportional to the diameter of the bolt.
Plain washers are available as machined or punched washers.
Machined washers
These washers are used for assemblies using machined components. These washers are available with chamfer on one side or on both sides. They are heat treated and ground.
Punched washers
These do not have chamfers and are commonly used in structural fabricatiion work.
Tapered washers
These are used in structural assemblies with tapered surfaces like inside of I-Beams, channels, etc. These washers help the bolt head or nut to seat squre to the hole.
Spring washers
Spring washers are used under nuts to prevent slackening of the nuts due to vibrations. They are made of spring steel, and when compressed they create tension between the bolt and the nut
Tab washers
These washers are used for locking the nuts
.
Toothed locked washers
These washers have serrations, cut and twisted. When placed between the nut and the assembly, this washer exerts friction on both the contacting surfaces. This prevents the nuts from slackening.
Specifiction
The Indian standard IS:2016-1967 designated a washer by name, type, size and number of the standard and material.
Example
A machined washer of size 10.5mm made of brass shall be designated as machined washer 10.5 IS:2016-brass.
Note
For detailed specification of different types of washers, refer to the following IS specification
Taper washer -IS: 5374 and IS:5372
Tab washer -IS : 8068
Toothed lock washer IS: 5371
Plain washer IS: 2016
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