Wave washers, also known as wave spring washers oz spring washers, are an ingenious and highly effective type of spring component designed to exert a compensating force when compressed. They are characterized by their distinctive corrugated or "wavy" profile, which allows them to function as a compact spring, most commonly to maintain a preload, absorb shock, or take up axial play in an assembly.
Unlike flat washers (which distribute load and prevent loosening) or traditional coil springs (which are designed for large deflections), wave washers are engineered to provide a specific, relatively low force over a small axial distance, making them ideal for applications with limited space.
WAVE WASHERS EXPLAINED: USES, SIZE CHART, MANUFACTURERS AND BUYING GUIDE
What is a Wave Washer?
A wave washer is a type of spring washer that features a series of undulations or "waves" around its circumference. When compressed, these waves flatten, providing a spring force that pushes back against the mating components. They are primarily used in static or infrequent dynamic applications where axial space is at a premium and a consistent, relatively small resistive force is required.
Key Characteristics:
- Corrugated Profile: The defining feature, creating the spring action.
- Axial Load Application: Designed to apply force along the axis of a shaft or bolt.
- Space-Saving: Their primary advantage over coil springs is their ability to deliver force in a significantly reduced axial space.
- Constant Rate (typically): As they flatten, they provide a predictable spring rate.
How Wave Washers Work
When a wave washer is installed between two components and compressed, its waves act like small springs. As the washer is flattened towards its "solid height" (the height when fully compressed), it generates a reactive force. This force is used to:
- Maintain Preload: Keep components tightly pressed together, preventing looseness or rattling.
- Compensate for Tolerance Stack-up: Absorb variations in component dimensions to ensure consistent assembly.
- Absorb Shock and Vibration: Dampen small movements and reduce noise.
- Fill Gaps: Bridge small axial gaps in an assembly.
Advantages of Wave Washers
- Axial Space Savings: The most significant advantage. Often requires 50% less axial space than a traditional coil spring for the same load and deflection.
- Consistent Resilient Force: Provides a predictable and uniform spring force.
- Shock & Vibration Absorption: Helps to dampen dynamic loads and reduce noise.
- Compensates for Thermal Expansion/Contraction: Maintains secure contact despite temperature changes.
- Eliminates Axial Play: Critical in bearing assemblies to prevent wobble.
- Accommodates Tolerance Variations: Ensures snug fits even with manufacturing variations.
- Cost-Effective: Often a more economical solution for axial spring force than custom coil springs or complex mechanisms.
Types of Wave Washers
While the basic principle is the same, wave washers come in several configurations:
- Single Turn (Crest-to-Crest): The most common type. A single continuous wave.
- Multi-Turn: Consists of multiple stacked turns of a single wave spring. These provide greater deflection characteristics and typically a lower spring rate for a given load.
- Nested Wave Washer: Multiple single wave washers nested inside each other. Used for very high forces in compact spaces.
- Gap/Overlap Type: Refers to how the ends of the wire meet. "Gap" has a small space, "Overlap" has the ends overlapping, influencing circumference and fitting.
Key Terminology
To select the correct wave washer, understand these terms:
- Outer Diameter (OD): The measurement across the outside of the washer.
- Inner Diameter (ID): The measurement across the inside hole of the washer.
- Free Height (FH): The height of the washer in its uncompressed state.
- Work Height (WH): The height at which the washer is designed to operate, providing its specified load.
- Solid Height (SH): The minimum height of the washer when fully compressed (all waves flattened).
- Material Thickness: The thickness of the wire or material used.
- Number of Waves: The count of undulations around the circumference.
- Load/Force: The spring force exerted by the washer at a given deflection or work height.
- Spring Rate (k): The change in force per unit of deflection.
Common Uses of Wave Washers
Wave washers are incredibly versatile and found in a wide array of applications across many industries:
- Bearing Preload: The most common use. They apply a constant axial force to ball bearings to eliminate end play, reduce vibration, and increase bearing life, especially in electric motors, gearboxes, and automotive applications.
- Valve Assemblies: Providing return force for valve seats, plungers, or flow control mechanisms.
- Clutch Assemblies: Maintaining tension on clutch plates.
- Connectors (Electrical/Fluid): Ensuring consistent contact pressure to maintain electrical conductivity or seal integrity.
- Gear Trains: Taking up backlash or axial play between gears.
- Brakes: Preloading brake components.
- Pumps: Maintaining sealing pressure or providing axial compensation.
- Actuators & Robotics: In compact mechanisms requiring precise linear force.
- Heavy Equipment: In various pivot points and connections.
- General Machinery: Anywhere small axial forces are needed in tight spaces.
Wave Washer Size Chart (General Guidance & Disclaimer)
IMPORTANT DISCLAIMER: There is no single universally standardized wave washer size chart that every manufacturer adheres to. Each manufacturer will have its own catalog with specific dimensions and corresponding load ratings for their product lines.
However, a typical wave washer chart will present information in a tabular format, usually organized by Inner Diameter (ID) in Outer Diameter (OD). You would then look for columns related to:
- Part Number: Unique identifier for the specific washer.
- Nominal Shaft Size / Bore Size: What ID/OD they are designed to fit.
- Actual OD (mm / inch)
- Actual ID (mm / inch)
- Free Height (FH) (mm / inch)
- Material Thickness (t) (mm / inch)
- Number of Waves
- Work Height (WH) (mm / inch) or range (e.g., from 70% to 50% of Free Height)
- Load at Work Height (N / lbf): The force provided at the specified work height. This is crucial.
- Solid Height (SH) (mm / inch):
- Minimum Deflection to Solid (mm / inch)
Example of a Fictional Chart Entry (for illustration only):
| Part No. | Shaft Dia. (mm) | OD (mm) | ID (mm) | Free Height (mm) | Material Thk. (mm) | # Waves | Work Height (mm) | Load @ WH (N) | Solid Height (mm) | Material |
|---|---|---|---|---|---|---|---|---|---|---|
| WW-15-22-3 | 15 | 22 | 15.5 | 1.8 | 0.3 | 3 | 1.0 | 35 | 0.9 | SS 302 |
| WW-20-28-4 | 20 | 28 | 20.5 | 2.5 | 0.4 | 4 | 1.5 | 60 | 1.0 | SS 302 |
| WW-30-40-5 | 30 | 40 | 30.8 | 3.2 | 0.5 | 5 | 2.0 | 90 | 1.2 | SS 17-7 |
How to Use a Manufacturer's Chart:
- Determine your required ID and OD: These will depend on the shaft/bore you are fitting into.
- Determine your required Load/Force: This is the critical parameter for maintaining preload or absorbing force.
- Determine your available axial space: How much compression can the washer undergo? This will relate to the Free Height, Work Height, and Solid Height.
- Find a Part Number: Look through the chart for a washer that meets your dimensional and load requirements.
- Calculate Deflection: Ensure the chosen washer can deflect from its free height to its work height within your operational limits without reaching solid height too early or having insufficient travel.
- Verify Material: Check if the material is suitable for your environment.
Often, you'll find ranges like:
- ODs: From a few millimeters (e.g., 5mm) up to hundreds of millimeters (e.g., 600mm or more).
- Number of Waves: Typically 3, 4, 5, oz 6 waves for single-turn washers. Multi-turn washers will have more.
Always refer to the specific manufacturer's catalog or online selector tool for definitive data.
Materials for Wave Washers
The choice of material is crucial for performance and longevity:
- Carbon Spring Steel (1070-1090): Economical, good strength. Often heat-treated and may be phosphate coated or zinc plated for corrosion resistance.
- Stainless Steel (302, 316): Good corrosion resistance, acceptable strength, and temperature performance. 316 offers superior corrosion resistance to 302.
- 17-7 PH Stainless Steel: Excellent strength, good corrosion resistance, and high-temperature performance (up to about 340°C or 650°F).
- Inconel X-750: For extreme high-temperature applications (up to 700°C or 1290°F) and highly corrosive environments.
- Beryllium Copper: Non-magnetic, highly conductive, and good for electrical applications.
- Phosphor Bronze: Good corrosion resistance, excellent electrical conductivity, and good for dynamic applications.
Platings/Coatings: Zinc, Phosphate, Cadmium, Electroless Nickel, and other custom coatings can be applied for enhanced corrosion resistance or specific surface properties.
Leading Manufacturers of Wave Washers
Several reputable manufacturers specialize in wave washers and other spring components. Some of the most well-known include:
- Smalley Steel Ring Company: A global leader, especially known for their Spirolox® spiral retaining rings and WaveRing® wave springs (a prominent brand in the wave spring space). They offer an extensive catalog and custom design capabilities.
- Associated Spring Raymond (a business of MW Industries): A large, diversified spring manufacturer offering a wide range of spring products, including wave washers.
- Lee Spring Company: Offers a comprehensive line of stock springs and custom springs, including wave washers.
- Gillen Company (A MW Industries Company): Another MW Industries division, specializing in retaining rings and wave springs.
- Arconic (formerly Alcoa Fastening Systems): While a broader fastener company, they may offer specialized spring washers.
- Custom manufacturers/regional specialists: Many smaller, specialized spring manufacturers also produce wave washers, often for specific industries or custom applications.
When sourcing, it's often best to start with these larger, well-established companies due to their extensive engineering resources, quality control, and wide product ranges.
Buying Guide: How to Select and Purchase Wave Washers
Follow these steps to ensure you select the correct wave washer for your application:
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Define Your Requirements:
- Application: What exactly will the wave washer be doing? (e.g., preloading a bearing, absorbing shock, taking up axial play).
- Available Space: What are the absolute maximum OD, minimum ID, and maximum axial height constraints? This is often the primary driver.
- Required Load (Force): What is the exact force (in N or lbf) you need the washer to provide at its work height? This is the most crucial performance parameter.
- Deflection Range: How much compression will the washer experience in operation (from free height to work height)? Ensure it doesn't reach solid height prematurely or have insufficient travel.
- Operating Temperature Range: (Minimum and Maximum) This impacts material selection.
- Environmental Conditions: Is corrosion a concern (moisture, chemicals, salt spray)? Are there magnetic requirements?
- Dynamic vs. Static Load: Is the load constant or does it fluctuate? This affects fatigue life considerations.
- Fatigue Life: How many compression cycles must the washer endure? (e.g., 100,000 cycles, 1 million cycles, etc.).
- Assembly Method: Manual or automated?
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Consult Manufacturer Catalogs/Selection Tools:
- Visit the websites of leading manufacturers (Smalley, Associated Spring Raymond, Lee Spring, etc.).
- Use their online product selectors. You typically input your ID, OD, and desired load, and the tool will filter suitable options.
- Download their full catalogs in PDF format for detailed specifications.
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Evaluate Standard vs. Custom:
- Start by looking for standard stock sizes. These are more readily available, generally more cost-effective, and have faster lead times.
- If a standard size doesn't meet all critical requirements (especially load and deflection in the available space), you will likely need a custom wave washer. Most reputable manufacturers offer custom design and manufacturing services. This will involve more engineering consultation and higher tooling costs for smaller quantities.
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Consider Material:
- Based on your temperature, corrosion, and strength requirements, choose the appropriate material (e.g., 17-7 PH SS for high strength, 316 SS for high corrosion resistance).
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Request Samples & Prototypes:
- For critical applications, request samples of potential washers to test in your assembly. This allows you to verify form, fit, and function before committing to a large order.
- For custom designs, request prototypes.
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Compare Quotes:
- Once you have a few suitable options (standard or custom), obtain quotes from multiple manufacturers or distributors. Compare not just price, but also lead times, minimum order quantities (MOQ), and customer support.
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Review Technical Data & Certifications:
- Ensure the manufacturer can provide relevant technical data, material certifications (MTRs), and compliance documents (e.g., RoHS, REACH) if required.
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Place Order:
- Once satisfied with selection, testing, and pricing, place your order.
Wave washers are a small but mighty component in mechanical engineering. Their ability to deliver precise axial force in a compact form factor makes them indispensable in countless applications, enhancing the reliability and performance of assemblies worldwide.