What Causes a Spring Washer to Lose Its Elasticity?

Spring washers are widely used in mechanical equipment, industrial machinery, automotive assemblies, and other bolted connections where elastic deformation is required. Unlike flat washers, which mainly provide a larger bearing surface for load distribution, spring washers are designed with a structure that allows them to deflect under compression and exert a restoring force.

However, this elastic behavior is not permanent under every operating condition. A spring washer may gradually lose its ability to return to its original shape after repeated loading, excessive compression, high temperatures, or unsuitable material selection. Once its elasticity decreases, the washer may no longer provide the intended spring action.

For manufacturers, engineers, and industrial component purchasers, understanding these causes is important when selecting spring washers and evaluating their long-term performance.

1. Excessive Compression Beyond the Elastic Range

One of the most common reasons a spring washer loses its elasticity is excessive compression during installation.

A spring washer is designed to deform within a specific working range. When a bolt is tightened, the washer is compressed and generates a restoring force. Within its elastic range, it can recover most or all of its original shape after the load is removed.

However, if the washer is compressed beyond this range, permanent deformation may occur. This condition is known as plastic deformation.

For example, excessive tightening torque may flatten a split spring washer or compress a wave washer beyond its designed deflection. Once this happens, the washer may not recover its original height or shape, resulting in reduced spring force.

The actual compression limit depends on the washer's geometry, material properties, thickness, and heat treatment. Therefore, tightening torque and assembly conditions should be considered together with the washer's load-deflection characteristics.

2. Repeated Loading and Material Fatigue

Spring washers experience repeated compression and recovery during service, especially in equipment exposed to continuous movement or changing mechanical loads.

Over time, repeated loading can contribute to material fatigue. Fatigue occurs when a material develops progressive damage under repeated stress cycles, even when individual loads are below its static strength.

The effects depend on several factors, including stress amplitude, material quality, surface condition, operating temperature, and the number of loading cycles.

For example, a spring washer installed in vibrating machinery may experience repeated changes in contact force. If the stress level is high or the material contains defects, fatigue damage can develop more quickly.

As fatigue progresses, cracks may form around highly stressed areas, particularly near edges, bends, or other geometric transitions. In severe cases, the washer may fracture. Before complete failure, its spring characteristics may also become inconsistent.

It is important to distinguish material fatigue from ordinary elastic deformation. A washer does not necessarily lose its elasticity simply because it has been compressed several times. Properly designed components can withstand repeated loading within their specified operating range. Problems are more likely when the applied stress and service conditions exceed the design assumptions.

3. High Operating Temperatures

Temperature is another important factor affecting spring washer performance.

Metal materials have different mechanical properties at different temperatures. When a spring washer operates in a high-temperature environment, its strength and ability to maintain elastic force may change.

Depending on the material grade and exposure conditions, prolonged heat can cause stress relaxation or tempering-related changes in mechanical properties. Stress relaxation is particularly relevant when a washer remains under compression for an extended period. Its internal stress and the force it applies may gradually decrease even if the washer's overall dimensions appear relatively unchanged.

For example, spring washers used near engines, industrial heating equipment, or high-temperature machinery may experience thermal exposure that differs significantly from ordinary indoor applications.

Material selection should therefore consider both the operating temperature and the duration of exposure. A material suitable for general machinery may not maintain the required spring characteristics in a continuously heated environment.

4. Improper Material Selection

The material determines much of a spring washer's mechanical performance, including hardness, strength, fatigue resistance, and elastic recovery.

Carbon steel and stainless steel are commonly used for metal spring washer production, but the specific grade and processing condition are important.

Carbon steel spring washers can provide suitable mechanical properties for many general industrial applications when the material composition and heat treatment are properly controlled. They are often selected for applications where mechanical strength and cost are important considerations.

Stainless steel spring washers are frequently used when corrosion resistance is required. However, stainless steel grades have different mechanical characteristics, and corrosion resistance alone does not guarantee adequate spring performance.

Copper and aluminum can also be used in various metal stamping components, but their suitability for spring washers requires careful evaluation. Not every copper or aluminum alloy provides the strength and elastic recovery needed for a particular spring washer design.

Selecting a material based only on its name or corrosion resistance can lead to unsatisfactory results. The required load, working deflection, operating temperature, and service environment should all be considered before production.

5. Inadequate Heat Treatment and Manufacturing Quality

Even when the correct material is selected, manufacturing quality has a significant influence on the final performance of a spring washer.

Many steel spring washers require appropriate heat treatment to achieve their intended hardness and mechanical properties. If the heat treatment process is poorly controlled, the washer may become too soft, too brittle, or inconsistent in its mechanical behavior.

A washer with insufficient hardness may deform permanently under normal assembly loads. On the other hand, excessive hardness or an unsuitable heat treatment condition can increase brittleness and the risk of cracking.

Manufacturing defects can also affect performance. Uneven thickness, inconsistent forming, rough edges, and surface cracks may create local stress concentrations. These defects can reduce fatigue resistance and cause premature failure.

For stamped metal components, consistent control of material quality, forming accuracy, heat treatment where required, and dimensional inspection helps reduce these risks.

6. Corrosion and Surface Damage

Corrosion is often considered a problem related only to appearance or material durability, but it can also affect the mechanical performance of spring washers.

When a washer is exposed to moisture, chemicals, salt, or other corrosive substances, its surface may gradually deteriorate. Corrosion can reduce the effective cross-section of the material and create small pits that act as stress concentration points.

These changes may accelerate fatigue damage, particularly when the washer is subjected to repeated compression.

Surface damage caused by improper handling, installation tools, or contact with abrasive components can create similar problems. Scratches and local deformation may affect the washer's ability to withstand repeated loading.

For applications in humid or corrosive environments, selecting an appropriate material or protective surface treatment can help extend service life. However, coatings and treatments should also be compatible with the washer's dimensions, operating conditions, and required mechanical performance.

How Can You Prevent Spring Washers from Losing Elasticity?

Preventing elasticity loss starts with selecting a washer that matches the actual fastening requirements. The washer's material, dimensions, working deflection, and expected load should be evaluated together rather than considered separately.

During installation, avoid excessive tightening that compresses the washer beyond its intended working range. Where necessary, follow the fastener manufacturer's torque recommendations and verify that the selected washer is suitable for the joint design.

For demanding applications, engineers should also consider operating temperature, vibration conditions, corrosion exposure, and expected loading cycles. These factors help determine whether a standard spring washer is sufficient or whether a different design is more appropriate.

Quality inspection is equally important. Depending on the application, relevant checks may include dimensional accuracy, hardness, material verification, surface condition, and load-deflection testing. These tests help confirm whether the washer meets the specified requirements.