Stretching spring, also known as tension spring, is a type of spring specifically designed to work under tension. Unlike compression springs that resist compression, tension springs are used for stretching or pulling. This fundamental difference enables tension springs to perform the opposite function as compression springs.

Therefore, steel tension springs have been widely used in machines and instruments. And there are various design forms of tension springs, including small tension springs, large tension springs, hooked tension coil springs, flat tension springs, adjustable tension springs, etc. In addition, customized stretching and compression nickel titanium alloy springs, high stretching springs, stretching spring rods, spiral stretching springs, galvanized stretching and compression springs, and more stretching spring material options are also available. Heli Spring is one of the leading manufacturers and suppliers of tension springs in China. We provide a variety of spiral tension springs and heavy-duty tension springs for many industries, such as door tension springs, cable tension springs, screen tension springs, sewing machine tension springs, tension spring tools, joystick tension springs, garage door tension springs, tension spring kits, furniture tension springs, chair tension springs, interior decoration tension springs, and more.

The coils of the tension spring are tightly wound with no spacing between them, which means that when the spring is stationary, there is no gap or space between the coils. When a load is applied to the tension spring, it will pull the coil apart, thereby generating resistance to the tension. This resistance will produce a "rebound" effect, causing the spring to return to its original shape after the force is eliminated. The ability to restore its original shape makes stretching springs an ideal choice for applications that require lifting heavy objects or maintaining constant tension in the system.
For example, in a trampoline, tension springs connect the mat to the frame, absorbing and redistributing energy during jumping. Similarly, in automotive applications, tension springs help to keep components such as the hood and trunk safely closed. The multifunctionality and reliability of tension springs make them an indispensable component in daily necessities and complex machinery.

Stainless steel tension springs are commonly used due to their heat resistance, and the 316 type has excellent corrosion resistance compared to the 302 and 304 types. The carbon content of 304 stainless steel is lower than that of 302 stainless steel, but their market value is similar. All four types of stainless steel tension springs are slightly magnetic, initially made into springs and then subjected to precipitation hardening to achieve the desired performance.
Similar to high carbon steel, stainless steel also has nominal chemical properties, density, torsional modulus, elastic modulus, minimum tensile strength, and maximum operating temperature. Copper alloys have excellent conductivity and heat resistance, making them very suitable for high-temperature applications. Monel 400 and Monel K-500 have significant effects in sub zero and low temperature environments. Monel 400 also has resistance to hydrogen sulfate, sulfuric acid, and hydrochloric acid, making it very suitable for marine and chemical applications. In addition, beryllium copper and phosphor bronze do not have magnetism and perform well at low temperatures. These alloys can achieve the desired properties through precipitation hardening after spring manufacturing. Base materials are highly valued for their excellent heat resistance and performance in chemical environments. Hastelloy is known for its excellent resistance to sulfur and chlorides, making it widely used in marine and waste management applications. NiSpan C has magnetism and can be used in timing devices, weighing systems, and geophysical equipment. This material undergoes precipitation hardening after spring manufacturing to achieve the desired performance. Inconel 600 performs well under high and low temperature conditions and is commonly used in aerospace and heat treatment processes.

Definition and Design
The design focus of a tension spring is to control the elongation and load capacity. Factors such as material, coil diameter, initial tension, and length under load determine their functionality. Initial tension refers to the force that keeps the coil spring together before any external force or load is applied. The initial tension must be overcome before the spring begins to elongate. When manufacturing tension springs, tightly wrap the coils together and set the initial tension during the process; Stretch springs have higher strength when wound to a higher initial tension. This design accuracy is crucial to ensure that they can reliably withstand repeated stretching and return to their original shape, and this quality is essential for their various applications in machinery and equipment.

Stretch spring end type
There are various types of end parts for tension springs. Here are some end types:
Traction rod spring
V-shaped hook above the center
There are small eyes on the side
Extend the center of the eye
Long end hook at the center
Conical end with rotating bolt
Cone end with rotating hook
Central upper half ring
There is a complete ring on the side
Machine Half View Center
There is a small offset hook on the side
There are double complete rings on the side
Machine cutting flat end
Central single loop

Stretching springs rely on hooks and loops to transmit force and perform their basic functions. Hook and loop can be customized into different types
Hook and loop play a crucial role in transmitting force and achieving the basic function of a tension spring. These end configurations can be customized into various types to suit specific applications.
Hook and loop type
Machine hook: This is the most widely used hook type, providing a secure and direct connection. They are made up of outward curved coils, providing a strong anchor point for tension.
Side loop: also known as a cross hook, located on one side of the spring body, with a more compact design. They are particularly useful when space is limited or when the spring needs to deviate from its center.
Central ring: a hook connected to the center of the tension spring. It is typically used for applications that require balancing loads.
Extended hooks: These hooks extend further from the spring body, providing a longer extension range and greater tension lever. They are typically used in applications where space is not limited and stronger tension is required.

Stretch spring shape type
Stretch springs can be designed in various shapes, such as:
awl
barrel
spiral
oval
cylindrical