Washers are small yet critical components in mechanical assemblies, functioning as spacers, load distributors, or protective devices in conjunction with bolts and nuts. They are available in various materials, including metals and plastics, and come in numerous types to suit different mechanical needs.
Washer Types and Functions
Plain Washers:
These washers primarily provide insulation and surface protection, preventing
damage during fastening, especially on painted or delicate surfaces. They also help distribute the load over a greater area and can adjust for oversized holes.
Types include:
Flat Washer:
A common variety used for load distribution and minimizing discrepancies in hole size.
Torque Washer:
Utilized in wood constructions with carriage bolts to keep the bolt from rotating
during tightening.
Fender Washer:
Named for its automotive use, it has a small inner diameter but a wide outer
diameter, ideal for distributing forces over a broad area, particularly with thin materials.
C-Washer:
Designed with a cutout, allowing for easier replacement without completely removing the fastener.
Finishing Washer:
Pairs with countersunk screws to provide a clean finish.
Spring Washers:
These washers possess a degree of axial flexibility, adding elasticity to the joint to
counteract vibration-induced loosening. Variations include:
Belleville Washer:
Conical in shape, providing axial flexibility and suitable for applications with
thermal expansion.
Crescent Washer:
Slightly curved to absorb minor movements and vibrations.
Dome Spring Washer:
Similar to the Belleville washer but with a flatter profile, offering a different level of compliance.
Wave Spring Washer:
Features a wave-like shape that acts as a cushion or spacer.
Locking Washers:
Engineered to prevent fastener rotation or loss of friction, these washers are vital
in applications with high vibration. Types include:
External Tooth Lock Washer:
Has radially outward teeth that grip into soft materials like plastic or aluminum to secure the fastener.
Internal Tooth Lock Washer:
Features teeth that bite into the fastener, offering shock and vibration absorption.
Split Lock Washer:
Appears as a flat washer cut and bent to create tension against the mating surfaces, maintaining fastener position.
Tab Washer:
Incorporates a tab that is bent against the nut or bolt head to prevent rotation.
Each washer type is designed with specific applications in mind, ensuring that any assembly can maintain integrity under various conditions, whether it's to distribute load, prevent damage to surfaces, absorb vibrations, or secure components against loosening.
