Extension Springs

• Functionality and Applications: Extension springs, also known as tension springs, are helical coiled springs designed to resist pulling forces. Unlike compression springs, which shorten when a load is applied, extension springs elongate under tension. They store energy when stretched and exert a pulling force to return to their original length once the force is removed. Extension springs are characterized by their initial tension, which is the force required to overcome the internal pre-load and begin separating the coils. They find widespread use in various applications requiring a pulling or return force, such as screen doors, trampolines, weighing scales, and tensioning devices. Other common uses include: counterbalance mechanisms, linkages, retractable mechanisms, and load balancing systems.
• Material Selection and Performance: Similar to compression springs, extension springs can be manufactured from a variety of materials to suit specific application requirements. Common materials include music wire (high strength and good fatigue life), spring steel (various grades offering different strength and flexibility), stainless steel (excellent corrosion resistance for harsh environments), and alloy steels (for high temperatures or specialized mechanical properties). The choice of material significantly influences the spring’s strength, elasticity, durability, corrosion resistance, and performance under specific operating conditions. Factors like wire diameter, coil diameter, number of coils, and the initial tension are crucial design parameters that determine the spring’s load-deflection characteristics and overall performance.

Extension springs are versatile components employed across numerous industries where a pulling force or the need to return a component to its original position is essential. Below are examples of how extension springs are utilized in precision applications:

• Precision Measurement Instruments: Used in sensitive weighing scales, force gauges, and calibration equipment where accurate and repeatable tensile forces are required for precise measurements.
• Actuators and Linkages: Employed in precision linear actuators and mechanical linkages where controlled extension and retraction are necessary for precise positioning and movement in robotic or automated systems.
• Tensioning Mechanisms in Optics: Utilized in optical instruments and laser systems to maintain precise tension on fibers, mirrors, or lenses, ensuring accurate alignment and performance.
• Medical Device Actuation: Found in certain medical devices requiring controlled and reliable pulling forces for actuation, such as in specific surgical instruments or drug delivery mechanisms.
• High-Performance Valves: Used in specialized valves where precise control of opening and closing forces is critical for regulating fluid or gas flow in sensitive systems.
• Robotics and Automation: Integrated into robotic arms and automated machinery to provide controlled pulling forces for gripping, manipulating, or returning components to specific positions with high accuracy.
• Semiconductor Manufacturing Equipment: Employed in delicate machinery used in semiconductor fabrication where precise tensioning or retraction of components is crucial for the manufacturing process.
• Aerospace Control Systems: Utilized in certain aerospace mechanisms where reliable and precise tensile forces are required for the operation of control surfaces or other critical components.

Need a CAD drawing? Try our free CAD configurator tool to produce standard or custom spring models.

We use a range of spring materials to meet the needs of our diverse customer base. Here are the materials we use most often and their maximum recommended % tensile: