Glossary

A Belleville spring washer is a conical-shaped disc that acts like a spring within a bolted or fastened joint. Unlike flat washers that simply distribute load, a Belleville washer flexes under compression, creating a reactive force that maintains tension even as the joint expands, contracts, or vibrates. Sometimes called conical spring washers or Belleville disc springs, they are named after Julien Belleville, the French engineer who patented the design in the 19th century.

The washer’s shallow cone shape allows it to deflect elastically when tightened under a bolt or nut. This action helps maintain clamping force despite joint relaxation, thermal expansion, or material creep, while also absorbing shock and vibration to prevent loosening. Belleville washers can also spread loads more evenly across a joint. Multiple washers can be stacked to tailor their performance: stacking in parallel increases load capacity, stacking in series increases deflection, and combining both allows for customized load-deflection behavior.

Belleville washers offer several advantages. They provide high load capacity in a compact form, maintain bolt tension under dynamic conditions, and perform well in vibration-prone environments. They can be tailored through stacking and are available in various materials, including carbon steel, stainless steel, and Inconel, to meet strength and corrosion resistance requirements.

These washers are widely used across industries. In automotive and aerospace, they are found in engines, brakes, suspensions, and landing gear. In power generation and heavy industry, they are used in turbines, compressors, and machinery to handle thermal expansion. In electronics, they maintain reliable pressure on connectors, while in structural and mechanical joints, they add security to fasteners exposed to fluctuating loads.

Overall, Belleville spring washers are essential where maintaining clamping force is critical. Their ability to deliver high spring force in a small space makes them indispensable in safety-critical and high-performance applications, often preferred over coil springs or wave washers for compact, reliable load management.