Disc springs are conical spring elements designed to provide stable, predictable, and repeatable elastic performance. They can be used to maintain nearly constant static loads or to withstand repeated loading and unloading under dynamic conditions.

Therefore, when selecting and designing disc springs, it is essential to understand how working compression and load conditions affect their performance.

1. How Should the Working Compression of a Disc Spring Be Selected?

The working compression of a disc spring has a direct influence on its load characteristics, stability, and service life.

Studies and practical experience show that the optimal working range is generally 15%–75% of the total available compression.

Within this range, the actual load-deflection curve of the disc spring is generally in good agreement with theoretical calculations, providing stable and predictable load output.

When the working compression is below 15%, residual stresses generated during manufacturing may still influence the actual load-deflection behavior. As a result, the measured performance may deviate from theoretical calculations, making the load characteristics less predictable.

When the working compression exceeds 75%, the disc spring gradually approaches a flattened condition. Its effective load arm becomes shorter, and the actual load curve begins to deviate significantly from the theoretical curve, showing an increasingly nonlinear behavior.

Therefore, keeping the working compression within the appropriate range is important for achieving predictable and reliable disc spring performance.

2. Disc Spring Service Life Under Static and Dynamic Loads

The service life of a disc spring depends largely on its operating load conditions. Applications can generally be divided into static-load and dynamic-load conditions.

Static Load

Static load refers to applications in which the disc spring continuously carries a relatively constant load, or where load changes occur infrequently.

The total number of load cycles during the design life is typically less than 10,000 cycles.

For static applications, the primary consideration is static strength rather than fatigue life. The maximum calculated stress at the critical area of the disc spring must remain within the allowable strength of the material.

For standard DIN disc springs, when the working compression is controlled within approximately 75% of the total compression, static-load applications can generally be designed without complicated theoretical stress calculations.

Dynamic Load

Disc springs used under repeated loading and unloading can generally be classified according to their required fatigue life:

1. Limited Fatigue Life
Approximately 10,000–2,000,000 cycles, commonly found in:

Construction machinery

Industrial equipment

Mold and die equipment

Automation systems

2. High Fatigue Life
More than 2,000,000 cycles, commonly required in:

Automotive applications

Aerospace

Valve systems

Railway equipment

Wind power equipment

For high-cycle applications, both proper spring design and appropriate manufacturing processes are essential to achieving long fatigue life.

3. The Importance of Preload and Final Load

Preload

Applying an initial preload to a disc spring has two major benefits.

First, preload helps eliminate residual tensile stress and improve fatigue life.

During manufacturing, residual tensile stress may remain near the upper edge of the inner diameter. During operation, this area can experience repeated transitions between tensile and compressive stress.

This stress reversal can accelerate fatigue crack initiation and propagation.

Therefore, it is recommended to maintain a continuous preload of at least 15% of the total compression during installation. This helps keep the critical area under compressive stress and can significantly improve fatigue life.

Second, preload helps the disc springs achieve better contact and more stable load distribution.

Because real disc springs cannot achieve perfect geometric symmetry, the contact surfaces may not initially be completely uniform.

As preload increases, the contact condition gradually improves and the load becomes more evenly distributed around the circumference. A slight increase in load during this process is normal and should be considered during precision design and testing.

Final Load

The final load is the maximum load experienced by the disc spring during operation. It directly determines the working stress level and has a significant influence on fatigue life.

As the final load increases, the internal stress of the disc spring also increases, while its fatigue performance decreases.

In general:

Lower working stress = longer fatigue life
Higher working stress = shorter fatigue life

4. Why Is More Than 75% Working Compression Not Recommended?

When the working compression exceeds approximately 75% of the total compression, the disc spring gradually moves away from its normal working range.

At this stage, the internal stress no longer increases in a relatively predictable manner but begins to rise rapidly and nonlinearly.

The resulting increase in stress can significantly reduce fatigue strength and shorten the service life of the disc spring.

Therefore, when the design allows, the final working load should be kept as low as reasonably possible to achieve a longer fatigue life.

5. How Can the Fatigue Life of a Disc Spring Be Improved?

One of the most effective ways to extend disc spring fatigue life is to reduce the working compression of each individual disc spring.

Lower compression means lower working stress, which can significantly improve fatigue performance.

If a system requires a larger elastic stroke, simply increasing the compression of a single disc spring is generally not the preferred solution.

Instead, disc springs can be designed in different combinations:

Series arrangement – increases the total deflection

Parallel arrangement – increases the load capacity

Series-parallel arrangement – provides a combination of greater deflection and higher load capacity

Through proper combination design, the required stroke and load can be achieved without excessively increasing the stress level of each individual disc spring.

Although disc springs have a relatively simple structure, their performance is influenced by several factors, including working compression, stress distribution, preload, and spring arrangement.

Properly controlling the working compression range can improve load stability, extend fatigue life, and reduce equipment maintenance costs.

For machinery that requires long-term and reliable operation, scientific disc spring design is far more important than simply pursuing higher load capacity.

At Raleigh Spring, we combine material selection, heat treatment, precision manufacturing, and application-specific design to provide reliable disc spring solutions for demanding operating conditions.

The right disc spring design is not simply about achieving a higher load — it is about achieving the right balance between load, deflection, stress, and service life.