Curved Spring Washers

Introduction to Crescent Washers

Curved washers, also known as crescent washers, spring washers, and curved spring washers, are a type of washer used in the same manner as a flat washer but offer spring force to provide a stronger hold and more resistance to vibration. These washers, also similar to wave washers, are designed to evenly distribute loads imposed by threaded bolts, screws, and nuts. The inside diameter will fluctuate depending on how much force is applied to alter the curve, which is a customizable feature to suit specific load and deflection requirements. Their application often involves absorbing axial end play or acting as lock washers.

Application Considerations

There are a few key factors to consider before using spring washers in your application.

Material Performance: Evaluate whether your application will benefit more from the additional spring force of spring steel or the corrosion resistance of stainless steel. Think about the crescent washer's exposure to natural or chemical elements, the expected load, and the required performance of the application (like the need to absorb axial end play).
Mating Fasteners: Think about the type of fastener that will pair with your washer. Is it threaded? What is the shank diameter? Will you need the washer's inside diameter to remain flexible? If so, consider the size of the fastener to ensure it will appropriately accommodate the washer.
Height: Ensure that the uninstalled height of the washer falls within the specified tolerance range to achieve precision in applications demanding accurate dimensions.
Load Requirements: Consider the weight of the light-duty load that your washer will need to tolerate and if it will absorb shock. This may influence the desired thickness of the part.

Benefits

Curved spring washers offer several advantages to applications when properly used and maintained.

Loosening Prevention: These washers exert light pressure on mating parts, effectively resisting loosening of machine components caused by vibration.
Uniform Load Distribution: By distributing loads evenly across threaded bolts, screws, and nuts, they help prevent excessive stress concentration and potential failure points.
Axial End Play Absorption: These washers absorb axial end play and help maintain proper alignment.
Cost-Effective and Reusable: Curved washers are reusable in general applications as long as they remain undamaged. Considering this advantage, they are significantly cost efficient when properly maintained.

Key Measurements

There are four measurements that are important to take when evaluating your spring washer:

Outside Maximum Diameter: The distance between the outermost edges of the circle
Inside Diameter: The distance between the walls of the inner hole
Overall Height: The height of the washer before it's installed
Thickness: The thickness of the metal

What is the Difference Between Curved Washers and Flat Washers?

The difference between these two washers is really as simple as their names imply; flat washers are flat, and curved washers are curved.

The most functional difference is that the curve in a spring washer provides more tension as the mating fastener is locked into position - this makes the connection stronger and more secure. Flat washers work best in scenarios that don't require the additional tension and are simply needed to relieve surface friction or prevent basic loosening on uneven surfaces.

What is the Difference Between Curved Washers and Wave Washers?

Curved and wave washers both have alternative names that include the word "spring" ( curved spring washers and wave spring washers ), so it can be confusing to differentiate between them. However, they look very different - curve washers feature a single arch and a thick metal ring, while wave washers feature thin metal with several waves that create 3, 4, or 6-point contact.

Wave washers are best used in thrust-loading applications for small deflections. They work well where radial space is limited and help offset tolerance deviations.

Other Types of Spring Washers

Curved washers are a subtype of spring washers, which feature deflection properties that ultimately help reduce vibration and provide tension. Other types of spring washers include:

Conical Disc: Handle high loads and limit deflection
Cup: Protect nuts and bolts, prevent tampering, and/or provide a finished look to an application
Finger: Offer deflection through their bent tangs that do not widen under pressure