Plain Washers
A plain washer is a thin plate, which is most commonly has a disk-shape with a hole in middle. It is widely used to distribute the load of a threaded fastener. Plain washers are used to provide a larger bearing surface where screws, bolts and nuts come in contact with the bearing surfaces.
The main role of flat washers is to increase the size of a screw’s bearing surface area, and reduce the surface pressure applied on the fastened object.
Looseness can result when the bearing surface sinks under the surface pressure, so using a flat washer to reduce the surface pressure is very effective.
This is especially crucial if the contact area between a screw’s bearing surface and the object being fastened is small when fastening to a slot, for instance, or if the object being fastened is made of soft material such as aluminum or resin.
NOMENCLATURE
d1 Inside diameter
d2 Outside diameter
s Thickness.
Incidentally, since flat washers are basically manufactured by pressing, one side has rounded corners and one side has burrs, as shown in the figure.
There is no fixed rule about which side goes up and which goes down, but given the issue of bearing surface pressure mentioned above, it’s more effective to put the burred side facing down.
However, since the burrs could mark the surface of the fastened object during tightening, it would be better to put the rounded side down if you want to avoid plating peeling.
There is a large range available to suit every application.
Plain Washers – Normal Series
The normal series is available as per the following standards
-
DIN 125
SS-304
SS-316
SS-304 Black
SS-316 Black
Titanium Grade 2
Nylon -
ISO 7089
SS-304
SS-316
SS-304 Black
SS-316 Black -
IS 2016 Type A
SS-304
SS-316
SS-304 Black
SS-316 Black -
JIS B1256 Normal Series
SS-304
SS-316
SS-304 Black
SS-316 Black
Plain Washers – Smaller OD
Smaller OD washers for Machine Screws are available as per the following standards.
-
DIN 433
-
IS 2016 Type B
SS-304
SS-316
SS-304 Black
SS-316 Black -
ISO 7092
SS-304
SS-316
SS-304 Black
SS-316 Black -
JIS B1256 Small Series
SS-304
SS-316
SS-304 Black
SS-316 Black
Plain Washers – Larger OD
Larger OD washers are used for irregular holes, softer materials and larger holes.
They are sometimes referred to as “Fender Washers” and distribute the load over a larger area making them useful for materials such as wood and plastics.
Large OD are available as per the following standards
-
DIN 9021
SS-304
SS-316
SS-304 Black
SS-316 Black
Mild Steel – Zinc White
Mild Steel – Zinc Yellow
Nylon -
IS 2016
-
ISO 7093
SS-304
SS-316
SS-304 Black
SS-316 Black -
JIS B1256 Large Series
SS-304
SS-316
SS-304 Black
SS-316 Black
Special Dimension Washers and Shim Washers
Special dimensions are also available under our Penny Washer Series and we have a range of SHIM washers as per DIN 988.
We ensure that every batch confirms correctly to the relevant standard and material grade.
Washers Materials
They are available in the following materials.
Mild Steel – Natural Finish, Zinc Plated and Nickel Plated.
Stainless Steel – AISI 304 and AISI 316 (Also available in Black Coating SS-304 and SS-316)
Titanium – Grade 2
Nylon
Nylon Washers
Nylon Washers are useful for weight saving and insulation applications.
Plain Washer Hardness
Class 100 HV : Minimum HV 140 (Rockwell B 56.2 minimum). Suitable for hexagon bolts and screws of product grade C in property classes up to and including 6.8; hexagon nuts of product grade C in property classes up to and including 6; case-hardened thread rolling screws
Class 140 HV : Minimum HV 140 (Rockwell B 75 minimum). Useful for majority of industrial applications including stainless steel assemblies.
Class 200 HV : Minimum HV 200 (Rockwell B 91.5 – C 29.8). Useful for higher demands in manufacturing, maintenance and repair.
Class 300 HV : Minimum HV 300 (Rockwell C 29.8- 40.8). Hardened and tempered. Best suited for use with through hardened screws, bolts and nuts.