Spring pitch involves many different variables, all of which can depend on what a spring is made of and what the purpose of the spring is.
The pitch can vary from music wire to chrome silicon, stainless steel to Elgiloy. The thickness of the spring can also come into consideration.
To best serve your system and ensure efficiency for your production and employees, it’s important to understand what spring pitch is and how it works.
What Is Spring Pitch?
Spring pitch is best defined in the context of helical springs.
A helical spring is sometimes confused with spiral springs, which often look similar.
These springs are created by circling wire along a cylinder’s surface in order to form a helix or corkscrew-like shape. Because of their shape, helical springs are usually formed of a single layer.
Since the helical spring has distance in the middle where the cylinder lay, there is a space in the middle of it. Spring pitch measures this gap.
When engineers and manufacturers refer to “spring pitch,” they mean the distance from one coil to the next.
The measuring point is usually from the center point of the wire. This distance is measured on a parallel with the spring’s axis of length.
Measuring Spring Pitch
Sometimes, the pitch of a spring can be estimated by measuring the gap between the coils of the spring, then adding in the wire thickness. However, springs in action are dynamic and undergo many different stresses.
Because spring pitch can be difficult and frustrating to measure on the surface of a spring, it might be best to use a formula or computer program to help you pinpoint it.
Spring pitch formulas usually take into account the:
- Geometry of the spring
- Stress
- Amount of force the spring will experience
- Height
- Amount of coils
- Density of the spring’s materials
- Maximum loads it will experience
- Its wire diameter
- Its length
Shear modulus, which is the amount of a material’s shear stress as related to the amount of shear strain it experiences, should also be taken into consideration.
Spring pitch determination to this extent usually involves extensive analysis and a great many calculations involving understanding of physics and geometry. Determining the pitch can be a complex operation, but an accurate answer will make for a safe and efficient machine.
Spring Material and Alloys
In some cases, it is best to consider the number of the spring’s active coils instead of what its pitch might be. However, in the case of helical springs, taking into account the material it is made of can also give you a better idea of how the spring will best operate.
Many springs are made of alloys, or what is known as a “superalloy” material.
Superalloys are alloys which usually involve man-made material which may or may not be mixed with naturally occurring matter. They are complex — often mixed with more than one material — and specifically designed to withstand unusually high temperatures.
This makes them especially effective in manufacturing and resistant to corrosion.
Types of Materials
1. These materials can include stainless steel, which is a popular alloy containing carbon, chromium, nickel, and iron. You are probably most familiar with stainless steel as a construction material or component of home appliances. That’s because stainless steel is fairly low-maintenance and corrosion-free.
2. In addition to stainless steel, springs might be comprised of phosphor bronze, another strong alloy which is made of tin, phosphorous, and copper. Phosphor bronze is strong, yet relatively easy to solder. It is a popular competent for springs because it features high fatigue resistance.
3. Less familiar, but still important, spring materials include chrome silicon, which offers tremendous tensile strength, and Nimonic 90, a combination of chromium, nickel, and cobalt.
4. Springs can also be made of MP35, another alloy of nickel and cobalt. It is known for its strength and ability to withstand even salt water or strong acids.
Spring Materials, Dimension, and Spring Pitch
A spring’s materials can affect its dimensions. Certain alloys and materials operate better in a variety of wires.
Depending on the application of the spring, adjusting these dimensions can have strong effects on how the spring operates within a manufacturing system. However, a great deal of consideration must go into making these decisions.
Importance of Diameter
When a spring has thick diameter, it is typically stronger than those which are made of thinner materials.
If the diameter of a spring is lessened, the spring usually isn’t as tight. That lessens the amount of stress the spring experiences, which also affects its height and length.
That’s why it’s so important for engineers to carefully take all these factors in consideration when measuring spring pitch: the dimension of the wire greatly affects that outcome.
Importance of Spring Index
Pushing the coils of spring closer together means that the spring’s index is smaller; this refers to the amount of force it exerts when it uncoils.
But if the diameter of the coil is made larger, the increased spring index will make for weaker “spring action.”
You might assume that the strongest spring is the best spring, but keep in mind that the stiffer a spring is, the more force it requires to compress.
- That means more energy to push the spring down, and a potentially dangerous amount of unleashed energy when it decompresses.
- On the other hand, a weaker spring will easily compress, but it might also snap easily or not provide the amount of decompression energy which is required.
Balancing Spring Pitch, Intention, and Design
This means that designers must take into consideration:
- The amount of stress a spring will endure
- How often it will compress in a work cycle
- What materials it is made of
You must also consider how far the spring with travel.
The amount of coils will affect its spring pitch, as will the amount of force a system might require.
Using a longer or shorter spring depending on what the spring is required to do — for example, if it is needed for industrial applications or in a consumer watch — also contributes to spring pitch considerations.
Do you need help with choosing the right compression spring materials or are in need of replacements? Contact KB Delta today.