How to Design a Spring: Specifications, Materials & Prototype Essentials
Designing a spring is as much about precision as it is about performance. Every coil, bend, and material choice influences how the spring behaves under real-world conditions. Whether it’s absorbing shock in an automotive system or withstanding extreme forces in energy applications, accuracy in design determines success.
At Lesjöfors, we specialize in turning design intent into dependable, custom-engineered spring solutions. Our global network of engineers, material experts, and testing facilities supports every stage, from concept and simulation to prototyping and full-scale manufacturing.
In this blog, we’ll explore how to design a spring, including why design accuracy matters, the different spring types available, and how to choose the right materials for optimal performance.
Why spring design matters
A spring’s design defines its behavior. A small variation in wire diameter, material grade, or number of coils can change its load capacity or fatigue life dramatically. The correct design specifications are critical, ensuring a spring performs consistently throughout its service life.
Every industry relies on tailored designs. In automotive, spring design affects suspension response and ride comfort. In medical devices, it determines precision and reliability. And in industrial systems, proper design ensures operational safety and efficiency.
Getting these parameters right from the start avoids costly redesigns, improves durability, and delivers predictable performance — all of which begin with a well-defined design process.
How to design a spring
Designing a spring involves defining its purpose, selecting the right type and material, and validating performance through analysis and testing. The spring design process typically includes six key stages:
1. Define the function and force requirements 2. Define constraints 3. Choose the right spring type 4. Determine key specifications 5. Select the appropriate material 6. Create a prototype, test, and refine
Let’s look at each step in detail.
1. Define the function and force requirements
Every spring design starts with understanding what the spring needs to do. Identify the type of movement or force it must provide, whether that’s pushing, pulling, twisting, or maintaining tension. Then define how far it needs to move (the travel distance) and how much load it must handle.
When designing a new spring at Lesjöfors, our engineers use this information to calculate load and deflection, i.e. how much force the spring must generate and how far it will compress, extend, or rotate. The relationship between these two values is defined by Hooke’s Law (F = k × x), where F is the applied force, k is the spring rate, and x is the deflection.
These calculations also help determine stress levels and operating frequency, ensuring the spring performs reliably without deformation or premature failure. From coil spring design to torsion spring design calculations, precise analysis of force–deflection relationships is key to creating a spring that performs consistently over time.
2. Define constraints
Understanding physical and environmental constraints ensures the spring integrates seamlessly with other components.
Space constraints
Available space dictates parameters such as free length, coil diameter, and solid height. For example, a compression spring operating in a confined housing must maintain full function within tight dimensional limits.
Environmental requirements
Springs exposed to moisture, chemicals, or temperature extremes must be designed accordingly. Material selection, surface treatments, and coatings are all adjusted to maintain performance.
Relationship to other components
Springs typically work in conjunction with other components, such as bearings, levers, or housings. Defining how a spring fits and operates within a system helps prevent premature wear or misalignment.
3. Choose the right spring type
Different applications call for different spring types. Selecting the right one is fundamental to achieving the desired motion and force characteristics.
Compression springs store energy under load and return to their original shape when released.
Torsion springs apply torque or rotational energy in mechanical assemblies.
Flat springs offer compact, linear deflection in confined spaces.
Constant force springs provide near-constant resistance throughout their range of motion
4. Determine key specifications
Once the spring type is defined, the next step is setting its physical parameters. These determine how the spring behaves under load and how it fits into the assembly.
Key design specifications include:
Wire diameter: affects stiffness, stress, and overall strength.
Coil count and pitch: influence load capacity and spring rate.
Free length and solid height: define working range and maximum deflection.
Spring rate (k): the force needed to compress or extend a spring by a unit length, expressed by Hooke’s Law (F = k × x).
Tolerances: ensure consistent performance during mass production.
Using simulation tools and design software, Lesjöfors engineers optimize these specifications to achieve the desired force, deflection, and fatigue life.
5. Select the appropriate material
Material choice is one of the most critical factors in spring design as it directly impacts strength, fatigue resistance, corrosion protection, and temperature performance.
Selecting the right spring material depends on:
Operating temperature range
Corrosive or chemical exposure
Electrical conductivity
Weight and space limitations
Expected fatigue life
Lesjöfors engineers evaluate these factors during the design stage to recommend the most effective and economical solution for your application.
6. Create a prototype, test and refine
Before production, physical prototypes validate design calculations and confirm performance under real-world conditions. Prototype springs allow engineers to fine-tune load capacity, deflection, and fatigue strength based on measured results.
Lesjöfors provides in-house prototyping and testing to accelerate development, reduce iteration time, and ensure every design meets its intended performance before full-scale manufacturing.
Common spring materials and when to use them
Selecting the right material is essential to achieving strength, resilience, and reliability. Below are some of the most widely used spring materials and their typical applications.
Stainless steel (302, 316L, 17-7PH)
Stainless steels are the most versatile and corrosion-resistant options. Grades such as 302 and 316L are ideal for humid or chemical environments, while 17-7PH offers excellent fatigue resistance and strength at elevated temperatures.
Carbon steel
A cost-efficient and high-strength material, carbon steel is widely used in general-purpose applications where corrosion resistance is not critical. It provides excellent fatigue life and stiffness when properly coated or plated.
Phosphor bronze and beryllium copper
These copper alloys combine good corrosion resistance with high conductivity, making them ideal for electrical contacts and precision instruments. They also provide excellent fatigue strength in dynamic environments.
Exotic alloys (Inconel, Elgiloy, titanium)
For extreme temperatures, aggressive environments, or aerospace-grade performance, high-strength alloys such as Inconel, Elgiloy, and titanium deliver outstanding durability and stability.
Prototyping and testing a spring design
Even the most precise calculations must be validated through testing. At Lesjöfors, when designing custom springs, our testing facilities evaluate components under simulated operating conditions to verify strength, fatigue resistance, and dimensional stability.
Our process includes:
Fatigue testing to assess performance over millions of load cycles.
Load and deflection testing to confirm theoretical models.
Environmental testing to evaluate performance under temperature and humidity extremes.
These validation stages ensure that every custom spring meets its performance targets before entering full-scale production.
Why work with Lesjöfors on spring design
Designing a spring is a balance of science, material expertise, and experience — and at Lesjöfors, we bring all three together. Our global engineering teams combine advanced simulation tools, decades of manufacturing knowledge, and a comprehensive material portfolio to deliver optimized, production-ready designs. From custom spring development to mass production, we provide consistent quality and performance across industries, from automotive to aerospace, and electronics to energy.
Every application is different, and many demand a fully tailored approach. Our engineers collaborate closely with you to refine geometry, material selection, and processing methods to meet exact performance requirements.
Engineers need details such as the required load, deflection range, available space, operating environment, and expected life cycle. These parameters define the spring type, material, and geometry needed to achieve the desired performance.
The best material depends on the application. Stainless steel suits corrosive or high-humidity environments, carbon steel is ideal for general use, and specialty alloys such as Inconel or Elgiloy are chosen for high-stress or high-temperature conditions.
Yes. Lesjöfors offers in-house prototyping and testing to validate designs quickly and efficiently. Our engineers refine geometry, material, and manufacturing methods based on real-world test results before full-scale production.
The cost of replacing a suspension spring will vary by vehicle and installer.
Lesjöfors engineers use advanced CAD and FEA-based simulation tools to model stress, deflection, and fatigue life. These digital simulations allow precise optimization before any prototype is produced.
Through a combination of accurate calculations, material selection, and physical testing. Lesjöfors validates every design with load, fatigue, and dimensional testing to confirm it meets specified performance targets under operating conditions.
