Hourglass Compression Springs

Barrel compression springs (also known as convex springs) are compression springs with a unique shape that is wider in the middle and narrower at the ends. This design offers enhanced stability, helps prevent buckling under load, saves space, and provides a progressive spring rate in some configurations, making them ideal for specific applications where traditional cylindrical springs might not be suitable.
Design and Function
The distinctive shape provides several functional advantages:
Reduced Buckling: The primary benefit of the barrel shape is its inherent resistance to buckling or bowing, a common issue with long, straight compression springs when compressed. This allows them to be used in applications where external guides are not possible.
Space Efficiency and Solid Height Reduction: The tapered ends allow the coils to "telescope," or fit inside one another, when fully compressed. This results in a reduced compressed (solid) height compared to a standard cylindrical spring of the same capacity, which is valuable in compact designs.
Progressive Spring Rate: Unlike cylindrical springs which typically have a linear spring rate (force is constant per unit of compression), barrel springs often have a progressive or non-linear rate. The force increases more as the spring compresses, as the larger coils begin to bottom out first.
Even Load Distribution: The curved profile helps distribute stress more evenly across the length of the spring, leading to increased durability and reliability.
Materials
Barrel springs are manufactured from various high-strength materials to ensure durability and performance in different environments:
High Carbon Steel (e.g., Music Wire): A general-purpose, economical choice with high strength, suitable for high-stress applications.
Stainless Steel (e.g., Type 302, 316): Offers excellent corrosion resistance and good performance across a wide range of temperatures, ideal for medical devices or outdoor use.
Alloy Steels (e.g., Chrome Silicon, Chrome Vanadium): These materials provide superior strength, toughness, and fatigue resistance for heavy-duty and high-stress environments.
Common Applications
Due to their unique benefits, barrel springs are used across numerous industries, especially where stability and compact design are critical.
Automotive Industry: Widely used in suspension systems, seat adjustment mechanisms, and clutch mechanisms for vibration dampening and shock absorption, enhancing comfort and safety.
Aerospace Engineering: Employed in control systems and landing gear components where lightweight, stability, and reliability under high loads are paramount.
Medical Devices: Found in compact, precision-sensitive equipment such as autoinjectors, infusion pumps, and surgical tools.
Industrial Machinery: Used in presses, valves, and various load-bearing mechanisms to maintain balance and reduce vibrations in high-stress environments.
Consumer Electronics: Their compact size makes them ideal for small, precise components like push buttons and battery contacts in everyday household electronics.