Finding the best possible design solution can be challenging when designing an application. Knowing what options are available can simplify the process.
Smalley provides an innovative and unique type of spring called a wave spring.
Springs play a vital role in countless applications, offering essential force and motion control. However, not all springs serve the same purpose. It's important to note that there are three main types of springs: compression, extension, and torsion.
Invented by Smalley more than 100 years ago, a wave spring is a type of compression spring made of flat wire with a unique multiple-waves-per-turn design. This design allows the wave spring to produce the same spring force and deflection as a traditional round wire coil spring but at 50% of its operating height.
Wave springs offer the added advantage of optimizing space in an application while maintaining form, fit, and function.
Similar to a traditional coil spring, a wave spring starts at free height. Free height is the natural height of the spring with no load applied, denoted as H in the image below. Work height, denoted as WH, is the height at which the spring is compressed at a specified load. As the wave spring is compressed, a load is output until a working height is reached. At the spring’s work height, the specified load is achieved.
This concept is displayed by the force-deflection curve in the graph on the top right. Let’s say you have two load requirements for your application, 20 and 28 lb. The first load is output at a working height of 0.08 in., as indicated by the curve’s leftmost blue ‘x’. The 28 lb. load requirement is output at a working height of 0.06 in.
Now let’s take a part number out of our catalog for a Crest-to-Crest Wave Spring, C100-M1. The spring has a free height of .250 in. and a working height of .087 in. At this designated work height, the Crest-to-Crest Wave Spring outputs a load of 18 lb. Beyond this work height, the spring may take a set, making the spring forces unpredictable.
Read more about wave spring work height and compression.
Smalley’s wave springs are manufactured using a process called edgewinding. This begins by cold rolling round wire to flat dimensions. Cold rolling causes the metal grains to elongate and lock together, improving the strength and stability of the material.
Once flattened, the wire is then coiled on edge to form a ‘crest-to-crest’ wave structure. The grain follows the direction of the coil, forming a circular-grain metallurgy that provides superior spring properties compared to stamped parts with unidirectional grain.
Edgewinding is a flexible and cost-effective process that enables customized designs without the need for tooling dies and with minimal material waste. In fact, it is the reason behind our No-Tooling-Cost™ policy. This method allows for seamless design changes at any stage, ensuring a quick and economical solution—whether for a prototype or full-scale production.
There are 5 main types of wave springs: Crest-to-Crest, Overlap- & Gap-Type Single-Turn, Nested Spirawave®, Wavo®, and Linear. While all wave springs are based on a “wave” type design, they all have distinct features that determine spring performance under load.
The use-case is described in the table below.
Table 1. Wave Spring types and their relative use-case.
Selecting the right material is critical for optimal spring performance. There are several factors to consider during spring material selection, such as operating environment, cycle life, and budget.
Standard Smalley wave springs are available in carbon steel and 17-7 stainless steel. Smalley stocks over 40 additional material options, including exotic alloys such as Inconel X-750® and Elgiloy®, to withstand practically any environment.
Table 2. Comparison of materials to environments.
From small to large diameters, light to heavy-duty loads, carbon steel to exotic materials, wave springs have been the trusted, space-saving solution for tens of thousands of applications. From everyday consumer products such as the smartwatch on your wrist to life-saving medical devices such as robotic surgical instruments to extreme environments like oil wells deep under the Earth's surface, to as high as Mars, there is virtually no limit for wave springs.
One common application that utilizes the benefits of a wave spring is a flow valve. As fluid pressure increases a Crest-to-Crest Wave Spring precisely controls the linear displacement of the piston. While many spring systems can be designed into valves, engineers often choose wave springs because of their space-saving capability and linear compression behavior through 80% of the compression range. These unique features allow for more precise and repeatable control of both flow and pressure.
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