Constant force springs are unique components used in various industries where a steady, consistent force is required.

Unlike traditional springs that exert force proportional to their displacement, constant force springs deliver nearly uniform force over their entire range of motion. This makes them ideal for applications that demand smooth, controlled movement without fluctuation in force.

How Constant Force Springs Work

A constant force spring is typically a tightly wound strip of metal that unrolls under a load, exerting a near-constant force as it extends.

These springs do not obey Hooke’s Law, which states that force is proportional to displacement. Instead, their force remains steady, making them suitable for applications requiring uniform tension or retraction.

The spring’s force is determined by factors such as material thickness, width, and the number of coils. The stored energy in the pre-tensioned strip allows the spring to extend smoothly while maintaining a consistent force output.

The ability to retract around a drum or spool enables these springs to be used in compact mechanical systems where space is limited.

Key Properties of Constant Force Springs

Constant force springs are designed with specific characteristics that make them ideal for precision applications:

  • Consistent force output: These springs exert a nearly constant force over their entire extension.

  • Compact design: The tightly wound coil structure allows for efficient use in limited spaces.

  • Durability: Made from high-strength materials such as stainless steel, these springs offer long-lasting performance.

  • Smooth motion: The controlled extension and retraction prevent jerky or inconsistent movement.

Applications of Constant Force Springs

Constant force springs are used in a variety of industries due to their ability to provide a stable force in dynamic applications.

Medical Devices

Constant force springs play a crucial role in medical applications where precise control is needed.

They are used in surgical instruments, diagnostic equipment, and adjustable hospital beds. The steady force they provide ensures smooth movement in medical devices, improving patient comfort and procedural accuracy.

Aerospace and Defense

In aerospace applications, these springs are used for counterbalancing mechanisms, retraction systems, and deployment devices. The ability to deliver reliable force in extreme conditions makes them invaluable for aircraft components and military equipment.

Automotive Industry

Automotive engineers rely on constant force springs for seatbelt retractors, cable tensioners, and window mechanisms. Their durability and consistent performance help enhance vehicle safety and comfort.

Consumer Electronics

Many everyday devices use constant force springs to improve user experience. They are found in retractable cords, battery contacts, and adjustable monitors. Their ability to maintain a stable force over repeated use ensures long-term functionality in electronics.

Industrial Automation

In manufacturing and industrial automation, constant force springs are used in conveyor systems, robotic arms, and tool positioning devices. They help maintain consistent tension and movement, reducing mechanical wear and enhancing operational efficiency.

Choosing the Right Constant Force Spring

Selecting the ideal constant force spring requires careful consideration of several factors:

  • Force requirements: Determine the exact force needed for the application to ensure optimal performance.

  • Material selection: Stainless steel is commonly used for its durability and resistance to corrosion.

  • Mounting method: Consider how the spring will be mounted and whether it will require a drum or spool.

  • Space constraints: Ensure the spring fits within the available space without compromising functionality.

Advantages of Constant Force Springs Over Other Springs

Constant force springs offer several advantages over traditional coil and torsion springs:

  • Consistent performance: Unlike conventional springs that lose force as they extend, these springs provide uniform force throughout their range.

  • Higher force output in compact sizes: They deliver strong force in a smaller footprint compared to other spring types.

  • Longer lifespan: The gradual extension and retraction reduce wear and tear, extending the operational life of the spring.

Custom Springs Are What We Do!

Constant force springs are essential components in industries that demand uniform force application.

Their ability to deliver steady force, durability, and compact design makes them the preferred choice for various high-precision applications. 

If you have a custom spring project that requires constant force springs, let us help you get them built. 

At Western Spring, we have the experience and know-how to make your constant force spring project a reality. Our expert team can help with design and our state-of-the-art manufacturing facility will get your project right every time.

Call or contact us today for more information.