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How Are Springs Made?

Springs are essential components in countless applications, from industrial machinery to everyday household items. You may be familiar with your car’s suspension springs, for instance, but less familiar with the medical springs that provide just the right amount of force to deliver life-saving medication in devices like EpiPens.

But how are those springs made? In many cases, spring manufacturing methods are similar regardless of the type and application of your springs. In every case, however, high-quality spring manufacturing is crucial, as faulty or substandard springs can lead to malfunctions, equipment failure, or even safety hazards. It may not be a big deal if the spring in your pen fails, but the spring in your car or a medical device is a different story. 

The use of premium materials and precise manufacturing techniques helps guarantee reliability and longevity in spring performance.

At a high level, spring manufacturing involves shaping metal wire into a specific form, often followed by heat treatments and surface finishing processes to enhance durability and performance. In this article we’ll dive into how springs are made, including exploring spring materials, manufacturing methods, and some common spring types.

What Materials are Springs Made of?

Springs can be made from many different types of materials. Some of the most commonly fit within a group called spring steel, refers to a group of carbon and low-alloy steels with high yield strength and excellent elasticity. Spring steel can withstand repeated stress without deformation, making it an ideal material for spring manufacturing. Other common materials include phosphor bronze, beryllium copper, and titanium.

Common Metal Spring Materials:

• High Carbon Steel – Offers excellent strength and durability but is prone to corrosion without proper coating.
• Stainless Steel – Provides corrosion resistance, making it ideal for applications exposed to moisture or chemicals. 316 stainless steel springs are ideal for medical and food applications.
• Alloy Steel – Enhances toughness and resistance to fatigue, commonly used in high-performance applications.
• Music Wire – A high-tensile steel known for its superior strength and resilience, frequently used in precision springs.
• Phosphor Bronze – Offers good corrosion resistance and electrical conductivity, used in electronic and marine applications.
• Beryllium Copper – Combines high strength with non-magnetic properties, often utilized in aerospace and electronics.
• Titanium – Provides exceptional strength-to-weight ratio and corrosion resistance, suitable for aerospace and medical applications.

Spring Manufacturing Processes

The manufacturing process for springs involves several precise steps, ensuring optimal performance and longevity.

Coiling & Forming

The first, and main, step in spring manufacturing is coiling and forming. This process shapes the metal wire into its final spring form using either cold coiling or hot coiling. Coiling machines use precision-controlled movements to ensure uniformity and accuracy.

Cold coiling is when material at room temperature is formed into a spring, while hot coiling processes heat the raw material in order to make it more malleable before forming. Cold coiling is the most common spring manufacturing process, but hot coiling is required for springs with thick wire diameters. The thicker the wire diameter, the harder it is for a spring to be formed via cold coiling, and the more likely it is that you will need to hot coil. 

In some cases, a spring is considered finished immediately after the forming stage. However, in many cases springs undergo secondary processes such as heat treating, shot peening, grinding finishing, presetting, and coating in order to gain the desired characteristics and functionality.

Heat Treating & Stress Relieving

Springs go through stress relieving and heat treatments to relieve internal stresses and enhance mechanical properties. This step helps ensure the spring retains its shape and improves its overall strength and elasticity.

Shot Peening

Shot peening is a process that enhances the fatigue resistance of springs. Small metallic beads or ceramic shots are blasted onto the surface, creating compressive stress that reduces the risk of cracks and failure.

Grinding

In certain applications, spring ends are ground flat to improve stability and load distribution. Grinding is particularly important for compression springs that require even contact surfaces.

Surface Finishing

Surface finishing processes, such as electroplating, powder coating, or passivation, are used to protect the spring from corrosion and wear, extending its lifespan in harsh environments.

Presetting

Presetting involves compressing or stretching the spring beyond its normal limits to improve fatigue resistance. This step ensures the spring maintains its intended shape and performance characteristics over repeated cycles.

Coating

To enhance durability, some springs undergo coating with materials such as liquid rubber or additional metal plating. This provides an extra layer of protection against corrosion and wear.

How Are Compression Springs Made?

Compression springs can be manufactured using hot or cold coiling. In many cases, the coiling and heat treatment processes are tailored to ensure uniform compression force distribution. These springs often undergo additional grinding and presetting steps to maintain stability and consistent performance under load.

How Are Torsion Springs Made?

Torsion springs are designed to store rotational energy, and are typically made via cold coiling. The torsion spring body is coiled with arms extending outward to apply torque. The wire is carefully shaped during the coiling process, and additional forming steps ensure the correct orientation of the spring ends. Heat treatment and shot peening are often used to enhance durability, as torsion springs are subjected to twisting forces.

How Are Extension Springs Made?

Extension springs, which resist tensile forces, are manufactured with hooks or loops at the ends. The coiling process ensures consistent spacing and tension distribution, while heat treatment enhances elasticity. Additional surface finishing steps may be applied to improve longevity and prevent wear due to repeated stretching. Extension springs are most frequently cold coiled, but can also be hot coiled.