Spring Wave Washer dimensions

Metric

(DIN 137 B)

Imperial

Commercial Standard Wave Spring Washers

Design Parameters

Spring wave washers (DIN 137 / DIN 6904) feature a "wavy" shape that creates a spring force through axial compression. They are designed to occupy minimal vertical space while providing a uniform load, making them ideal for taking up "play" or maintaining tension in assemblies.

Engineering Note: Wave washers are best suited for static or light-duty dynamic loads where space is highly constrained. Unlike split washers, they provide a more distributed, 360-degree contact surface, which makes them the standard choice for preloading ball bearings to reduce noise and vibration.

Engineering Deep Dive: The Mechanics of Wave Washers

Spring wave washers (sometimes called wavy washers) are the low-profile solution for maintaining tension in tight axial spaces. While a standard coil spring or a thick disc spring (Belleville) requires significant vertical depth, a wave washer can provide controlled spring force in a footprint often less than 2mm thick.

The Primary Mission: Eliminating "Play"

The most common use for a wave washer is taking up cumulative tolerances in a mechanical assembly. In a stack-up of parts—gears, spacers, and bearings—manufacturing variances can leave a small gap. If left unchecked, this "axial play" causes rattling, audible noise, and increased wear. A wave washer acts as a persistent, gentle cushion that keeps the assembly snug without the rigid interference of a shim.

Precision Bearing Preload

In the world of electric motors and high-speed spindles, wave washers are indispensable for preloading ball bearings. By applying a constant axial load to the outer race of a bearing, the washer forces the balls into consistent contact with the raceways.

• Noise Reduction: It prevents the "chatter" that occurs when balls rattle in an unloaded bearing.
• Longevity: It ensures the balls roll rather than slide, which prevents flat spots and galling. When selecting a washer for this purpose, ensure the OD aligns with the outer race of your bearing (e.g., matching a 608 or 6200 series) and that the ID provides enough clearance for the shaft to rotate freely.

Load vs. Deflection: Finding the Sweet Spot

Engineers need to look closely at the "Spring Rate." A wave washer's load increases linearly as you compress it, but only up to a point. Once you compress the washer past 80% of its free height, the rate becomes non-linear and incredibly stiff as the material begins to flatten against the mating surface.

For a reliable design, aim to have your "installed height" fall between 30% and 70% of the total available deflection. If you crush the washer completely flat during installation, you risk a "permanent set," where the steel exceeds its elastic limit and fails to return to its original height. This effectively kills the preload in your joint and can lead to assembly failure over time.

Stacking and Multi-Wave Designs

If a single washer doesn't offer enough travel or force, they can be stacked:

1. Series Stacking (Back-to-Back): This increases the total deflection (travel) while keeping the spring force the same as a single washer.
2. Parallel Stacking (Nested): This increases the spring force but keeps the travel the same.

Note that nested washers can sometimes generate internal heat due to friction between the overlapping waves in high-cycle applications. For designs requiring high travel and consistent force, a "multi-turn" wave spring is often a superior mechanical choice.

Material Selection for Longevity

Most "off-the-shelf" wave washers are made from High-Carbon Spring Steel (C60/C75). These are cost-effective and provide excellent spring characteristics but are highly prone to corrosion.

For applications exposed to moisture or chemicals, 301 Stainless Steel or 17-7 PH Stainless is required. 17-7 PH is particularly prized in aerospace and high-performance automotive sectors because it can be precipitation-hardened after forming, allowing it to maintain its spring temper at much higher temperatures where standard stainless might go "soft."

Common Design Pitfalls

A frequent mistake is placing a wave washer directly against a soft material like plastic or unhardened aluminum. Over time, the "peaks" of the waves can dig into the soft surface (a process called Brinelling). As the peaks sink into the material, the effective gap increases and the axial tension drops. To prevent this, always place a hardened flat washer between a wave washer and a soft substrate to protect your components and maintain your preload.

Standard Reference Comparison

Note: For high-speed rotating assemblies, ensure the washer is centered correctly. An eccentric wave washer can introduce significant balance issues at high RPMs.