Introduction
This article provides a comprehensive overview of extension springs and their applications.
You will learn about the following topics:
- What extension springs are
- Materials used in extension spring production
- Extension spring finishing techniques
- Manufacturing processes for extension springs
- How extension springs work
- Different types of extension spring ends
- Common applications of extension springs
- And more...
Chapter One – Understanding Extension Springs
Extension springs are a type of helical spring designed to resist stretching forces and return to their original shape when the force is removed.
These springs feature tightly wound coils that create internal tension, helping them resist stretching forces. The amount of tension affects how tightly the coils are wound and how they attach to other components. Typically, extension springs have loops, hooks, or coils at each end for easy attachment during use.
Extension springs effectively store and absorb energy while resisting pulling forces. When components attached to the spring move apart, the spring's tensile strength pulls them back together. These springs are used in various applications, including hardware, washing machines, doors, toys, aircraft landing gear, and truck hoods. Below is an illustration of an extension spring:
Chapter Two – Materials Used for Extension Springs
Extension springs, also called tension springs, are mechanical components that store and release energy when stretched. Choosing the right material is crucial for performance, durability, and reliability in different applications. The material affects load capacity, corrosion resistance, fatigue strength, temperature tolerance, and cost. Key factors in material selection include:
- Spring design and operating conditions (load, stress, deflection)
- Required corrosion and chemical resistance
- Operating temperature range
- Magnetic properties
- Electrical conductivity (for specialized uses)
- Industry-specific standards
While carbon steel is commonly used, other materials like stainless steel, copper alloys, nickel alloys, and engineered plastics are also employed for specific needs.
High Carbon Steels (Spring Steels)
High carbon steels, containing 0.60% to 1.00% carbon, offer excellent strength and fatigue resistance. They are widely used in industrial, automotive, and general-purpose applications. These steels can be heat-treated and cold-drawn for enhanced toughness and tensile strength.
Alloying elements like chromium, manganese, and vanadium improve performance in high-stress environments. Specialized alloys include:
- Chrome Vanadium Steel: Known for toughness and impact resistance, ideal for heavy-duty applications.
- Chrome Silicon Steel: Offers high tensile strength and performs well at elevated temperatures.
- Chrome Silicon Vanadium Alloy: Combines the best properties of both for maximum durability.
These materials are available in various forms, each suited to specific environments.
Common High Carbon Steel Types
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Music Wire – Known for uniformity and fatigue resistance, used in precision springs.
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Hard Drawn MB – Cost-effective for low-stress applications.
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Oil Tempered MBM – Provides shock resistance for commercial springs.
Stainless Steels
Stainless steel springs are ideal for corrosive environments, offering durability and non-magnetic properties. They are commonly used in marine, medical, and food processing applications.
Popular Stainless Steel Grades
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Stainless Steel 302 – General-purpose corrosion resistance.
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Stainless Steel 304 – Better resistance to weld decay.
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Stainless Steel 316 – Excellent saltwater and chemical resistance.
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Stainless Steel 17-7 PH – High strength after heat treatment.
Alloy Steels
Alloy steels are chosen for high-stress applications, offering enhanced strength and durability. They are common in automotive and industrial sectors.
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Oil Tempered Chrome Vanadium Spring – Standard for heavy-duty applications.
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Oil Tempered Chrome Silicon Spring – Performs well in high-temperature environments.
Copper Alloys
Copper alloys provide excellent conductivity and corrosion resistance, making them suitable for electronics and marine applications.
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Phosphor Bronze – High fatigue resistance for electrical applications.
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