Types of washers
Contents |
[edit] Introduction
A washer is a thin disc-shaped plate, typically with a hole through the centre, that is used in conjunction with a threaded fastener (such as a screw or bolt) to:
Washers are most commonly made from metal or plastic, although rubber and fibre versions are also available.
Although they can vary widely, in general, washers have an outer diameter that is approximately twice the inner diameter.
There are three main categories of washer:
[edit] Plain washers
Also known as a flat washer, this type of washer is a flat annulus or ring which is used to spread the load of a screwed fastening and prevent damage to the surface being fixed.
Types of plain washer include:
- Penny washer (or Fender washer): A flat washer with a larger outer diameter proportional to the central hole, meaning it can distribute loads more widely.
- Spherical washer: Consists of one radiused surface which, when used with a mating nut, allows for several degrees of misalignment between parts.
- C-washer: Can be slid in and out of position on a bolt or shaft.
- Countersunk washer: When secured, this type of washer creates a flush surface.
[edit] Spring washers
This type of washer has axial flexibility which helps prevent fastening or loosening as a result of vibrations or shock.
Types of spring washer include:
- Belleville washer: Has a slight conical shape which helps maintain tension in assemblies where there is thermal expansion and contraction.
- Curved disc spring: Is only curved in one direction and so is used to support relatively light loads with a wide deflection range.
- Wave washer: Has a ‘wave’ in the axial direction which makes it suitable for use as a cushion spring or spacer.
- Split washer: Has a ring that is split at one point and bent into a helical shape creating more friction and rotation resistance.
[edit] Locking washer
This type of washer is often interchangeable with spring washers and prevents fastening or loosening rotation.
Types of locking washer include:
- Helical spring: Increases the pre-load on the fastener while tightening. This provides protection against loosening.
- Toothed lock washer: Has serrations around its edge that can extend inward or outward to bite into the surface material and provide maximum torsional resistance.
- Tab washer: Has a side tab that can be bent into place against a nut, preventing rotation.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
What it is and how to use it.
Investors in People: CIOB achieves gold
Reflecting a commitment to employees and members.
Scratching beneath the surface; a guide to selection.
ECA 2024 Apprentice of the Year Award
Entries open for submission until May 31.
UK gov apprenticeship funding from April 2024
Brief summary the policy paper updated in March.
For the World Autism Awareness Month of April.
70+ experts appointed to public sector fire safety framework
The Fire Safety (FS2) Framework from LHC Procurement.
Project and programme management codes of practice
CIOB publications for built environment professionals.
The ECA Industry Awards 2024 now open !
Recognising the best in the electrotechnical industry.
Sustainable development concepts decade by decade.
The regenerative structural engineer
A call for design that will repair the natural world.
Buildings that mimic the restorative aspects found in nature.
CIAT publishes Principal Designer Competency Framework
For those considering applying for registration as a PD.
BSRIA Building Reg's guidance: The second staircase
An overview focusing on aspects which most affect the building services industry.
Design codes and pattern books
Harmonious proportions and golden sections.
Introducing or next Guest Editor Arun Baybars
Practising architect and design panel review member.