Compression Springs

Compression springs are helical springs designed to resist compression along their axis of wind. They are commonly used in various applications due to their efficient energy storage capabilities. These coil springs can function independently or be mounted over a guide rod or inserted into a hole. When a load is applied to a compression spring, causing it to shorten, the spring exerts a force in the opposite direction, attempting to return to its original length.

The energy stored in a compression spring depends on factors such as the material properties, wire diameter, and number of coils. The stiffness of the spring, known as its rate, is determined by the wire diameter and the number of coils. The rate indicates the change in force per unit change in length and is typically measured in pounds per inch or newtons per millimeter. Adjusting the wire diameter or the number of coils allows for customization of the spring’s rate.

Compression springs are utilized in a wide range of applications, from automotive engines and industrial stamping presses to household appliances, lawn mowers, medical devices, cell phones, electronics, and delicate instruments. They are commonly used in push button mechanisms and conical types are preferred for applications requiring minimal solid height and increased resistance to surging.

We are professional spring and wire forming manufacturer in China for many years. We hereby wish to introduce the Characteristics of this spring and how to custom-made springs which can meet the request for your new projects. Meanwhile, we explained our custom-made spring ability,such as material we can offer,Size, surface treatment and so on.

 

Characteristics of compression springs

Characteristics of springs

The following figure shows the basic geometric parameters and characteristic relationships of a cylindrical spiral compression spring.

Basic geometric parameters and characteristic relationships of compression springs

 

F_1,2,3…F_n are the working loads, corresponding to deformations f_1,,f₂,…, f_n. The test load that reaches the torsional test stress τ s is denoted as F_s, and the deformation under the corresponding test load is denoted as  f_s. Let the load on the spring during compression be Fb, and the corresponding compression deformation be f_b.In order to ensure stable stiffness of the spring during operation and to guarantee the load at the specified height, the deformation of the spring should be between 20% and 80% of the deformation f_s under the test load, that is

0.2 f_s ≤f_1,2,3…n≤0.8 f_s

The corresponding workload should meet the following requirements:

0.2 F_s ≤f_1,2,3…n≤0.8 F_s

When there is a special need to ensure stiffness, its stiffness is determined by the ratio of the load difference between two load points and the deformation difference, ranging from 30% to 70% of the deformation f_s under the test load,namely

F=（F₂-F₁）/（f₂-f₁）

F₁ is generally the preload during installation.

Test load

The test cut-off load Fs is the maximum load that the spring is allowed to withstand when measuring its characteristics. Its value can be derived from the curvature coefficient K=1:

F_s=(πd³/8D)τ

If due to raw material and process reasons, when calculating the test load F_s, for ammunition with a twist ratio C ≤ 6, an additional factor can still be added
Curve correction coefficient K.

The value of springs with Class I and Class II loads shall not exceed the maximum test shear stress value or its corresponding maximum test load value.

Solid load

The Solid load F_b is the theoretical load when the spring is compressed, and the corresponding compression and deformation amount is f_b.

F_b≥F_s   or f_b≥f_s

 

Structure of compression spring

Structural types and related parameters of compression springs

There are many types of spring end structures, which can be designed according to work requirements. When the diameter of the spring material is large, the support figure number should be small, otherwise it should be large.
The structural type with two end rings tightly together has good verticality between the end ring and the spring axis, and good contact with the support seat, so it has higher working stability. The end rings are not tightly together, and the structure is simple, but in order to ensure the stability of the spring, a support seat that matches the spring end ring is required. It is often used under conditions with low requirements or static loads, and is also used for springs with thin spring wires and large windings.
Experience shows that in order to reduce the influence of load eccentricity, when the winding ratio is between 3 and 10, the end surface of the spring is best ground; when it is between 10 and 15, the end can be ground or not: when it is greater than 15, it can be ground.

The end of the compression spring of rectangular cross-section material is generally contact-type, and the end surface is ground.

End structure of compression spring

• Two ends of coils are closed and ground
• Two ends of coils are closed but not ground
• Two ends of coils are not tightened
• Two ends of coils are closed, ground or not ground
• Two ends are flattened and closed, not ground or ground

Spring material diameter

The spring material diameter d should be calculated according to the corresponding formula. If there is a special need, the selected value should comply with the material diameter specification.

Spring coil diameter

The spring center diameter D is the nominal diameter of the spring. The deviation of the outer diameter or inner diameter should be strictly controlled. The deviation value can be found according to the national standard. In order to ensure sufficient space, it should be considered that the spring coil increases after the spring is loaded. When the two ends of the spring collar are fixed and the spring is pressed from the height of the spring to the tightness, the increase in the middle diameter is different.
When the two end surfaces and the support seat can rotate from the height of the spring and the friction force is relatively small, the increase in the middle diameter is also different.

The winding ratio of the spring (spring index)

The smaller the winding ratio C value, the greater the curvature, the more difficult the winding, the more the shear stress on the inner side of the spring material cross section is greater than the average stress during operation, and the greater the stiffness of the spring. The larger the C value, the opposite is true.

The number of coils of the spring

In order to avoid excessive additional force caused by load eccentricity, the minimum number of working coils is 2, but generally not less than 3 coils. The number of coils of the support depends on the end turn structure type. The total number of turns n1=n+n2, the last digit of the total number of turns n1 should be 1/4, 1/2 or a full turn, and 1/2 turn is recommended.

The height of the spring

• 1) Free height, the free height Ho of the compression spring refers to the height in the free state. Its value is affected by the end structure and it is difficult to calculate the exact value.
• 2) Working height
• 3) Test height Hs, which is the height corresponding to the test load Fs
• 4) Compression height Hb. In principle, it is not specified.

Helix angle and rotation direction of spring

• 1) Helix angle α

The recommended value is 5° to 9°. If α≥9, the influence of the helix angle should be considered when calculating the deformation.

• 2) The rotation direction of the spring coil is generally right-handed. In the combined spring, the rotation direction of each layer of spring is the same for left and right rotation, and the outer layer is right-handed

Pitch of spring

Unfolded length of spring material

The wire diameter d, the spring center diameter D and the number of coils n are the three basic parameters of the spring. When these three parameters are determined, the basic performance, strength and stiffness of the spring are determined.

Typical drawings of compression springs

Typical drawing of compression spring

The following figure is a typical drawing of a cylindrical helical compression spring. According to the requirements, the drawing should include technical requirements and design parameters.
Typical drawings of cylindrical helical compression springs

 

Technical requirements for compression springs

The technical requirements include the following:

• Spring end form:
• Total number of turns:
•  Effective number of turns n:
• Direction of rotation:
• Surface treatment:
• Manufacturing technical conditions.
  When necessary, the requirements for setting treatment, strengthening treatment, and use conditions such as temperature and load properties can be indicated.

 

Load types and allowable stresses of Compression Springs

Static load and dynamic load

(1) Static load

• 1) Constant load:
• 2) The load changes, but the number of cycles N<104.

(2) Dynamic load

The load changes, and the number of cycles N≥10. According to the number of cycles, dynamic loads are divided into:

• 1) Limited fatigue life: cold-rolled spring load cycles N≥10~106: hot-rolled spring load cycles
  N≥10~103.
• 2) Unlimited fatigue life: cold-rolled spring load cycles N≥10? times; the number of load cycles of hot-rolled springs N≥
  2×106.
  When the number of load cycles of cold-rolled springs is between 106 and 10? times, and the number of load cycles of hot-rolled springs is between 10 and 2×106 times, the design can refer to the limited or infinite fatigue life according to the use conditions.

Principles of selection of allowable stress

• 1) For springs under static load, in addition to considering the strength conditions, if there are requirements for stress relaxation, the allowable stress should be appropriately reduced.
• 2) For springs under dynamic load, in addition to considering the number of cycles, the stress (change) amplitude should also be considered. At this time, according to the cycle characteristics, when the cycle characteristic value is large, that is, the stress (change) amplitude is small, the allowable stress takes a large value; when the cycle characteristic value is small, that is, the stress (change) amplitude is large, the allowable stress takes a small value;
• 3) For springs with important uses, whose damage has a great impact on the entire machinery, and for springs working at high or low temperatures, the allowable stress should be appropriately reduced.
• 4) Springs that have been effectively shot peened can improve fatigue strength or fatigue life.
• 5) For compression springs, effective strong pressure treatment can increase fatigue life and have a significant effect on improving spring performance.
• 6) There are many factors that affect the fatigue strength of springs under dynamic loads, which are difficult to accurately estimate. For springs with important uses, tests should be conducted after the design is completed.

 

Custom Compression Spring Manufacturer

ChinaCustomSpring provides comprehensive custom compression spring services and engineering assistance from initial design to final production. Custom compression springs can be crafted in various sizes and materials to suit specific requirements. Popular materials for compression springs include stainless steel, carbon steel, chrome silicon, and music wire.

ChinaCustomSpring offers sophisticated capabilities and a diverse range of options for custom compression spring manufacturing, including advanced quality control systems, regulatory expertise in compliance with RoHS, REACH, and DFARS, CAD-assisted product design, in-house prototype production services, and a global supply chain network. Lee Spring holds ISO 9001:2015 certification, adheres to REACH and RoHS regulations, and is ITAR Registered.

Whether you need custom compression springs in small or large quantities, we can accommodate your needs. ChinaCustomSpring is equipped to supply for short production runs, ensuring flexibility and efficiency in meeting your requirements.

Material

We offer a wide range of materials to meet the diverse needs of our customers. From stainless steel and carbon steel to alloy steel and other specialty materials, we have the flexibility to accommodate different project requirements. Our materials are carefully selected for their durability, strength, and resistance to wear and corrosion, ensuring maximum longevity and performance.

• Carbon steel : 65Mn,72A,82B and so on
• Stainless steel: SUS302,SUS304, SUS316 and so on
• Music wire
• Copper wire
• Aluminum wire
• Others to be discussed

Wire Diameter

Size tolerance is a critical aspect of compression springs, and we adhere to stringent standards to guarantee dimensional accuracy. Our commitment to excellence ensures that our springs conform to the industry-standard size tolerance specifications. This attention to detail allows for optimal functionality and precise fit in a variety of applications.

From 0.1mm to 20mm

The tolerance can be ±0.05 mm

Finish

We offer full range of finish treatment, which can save time and cost for your spring products.

• Plating:Zinc ,Nickel,Silver,Tin,Chorme and so on
• Anodic oxidation
• Black oxided
• Electrophoresis
• Power coating
• Oil coating
• Sand blasting
• Polishing
• Passivation
• Etc

Application

Our compression spring have a wide range of applications across various industries. These springs, known for their ability to store energy when compressed and release it when the force is removed, are integral components in many mechanical systems. Here are some common applications of compression springs we made for our customers:

• Automotive Industry
• Industrial Machinery
• Aerospace and Defense
• Medical Devices
• Electronics
• Furniture
• Agricultural Equipment
• Garage Doors
• Etc

Heat Treatment Hardening for Compression Springs

To ensure optimal functionality and durability, the surface treatment of these springs is of paramount importance. At ChinaCustomSpring, a leading spring manufacturer in China, we understand the significance of surface treatment. Therefore, we offer a wide range of common surface treatment methods to meet our customers’ specific needs.

1. Importance of Surface Treatment:

Surface treatment plays a crucial role in enhancing the performance and lifespan of compression springs. It provides several key benefits, including:

• a) Corrosion Resistance: Springs often operate in demanding environments where exposure to moisture, chemicals, and other corrosive elements can degrade their integrity. Through proper surface treatment, such as plating or coating, compression springs gain resistance against corrosion, ensuring their longevity and reliability.
• b) Wear Resistance: As compression springs are subjected to repeated compression and relaxation cycles, wear and abrasion become inevitable. Surface treatments like heat treatment hardening create a hardened layer on the spring’s surface, significantly reducing wear and extending its service life.
• c) Improved Fatigue Strength: Compression springs are designed to withstand millions of cycles without failure. By subjecting the springs to heat treatment hardening processes, their fatigue strength is improved, enabling them to endure higher stress levels and prolonged usage.

2. Heat Treatment Hardening:

Heat treatment hardening is one of the most effective methods employed to enhance the durability of springs. This process involves heating the springs to a specific temperature range and then rapidly cooling them, resulting in increased hardness and strength.

• a) Quenching: In the heat treatment hardening process, quenching is a critical step where the heated compression springs are rapidly cooled by immersing them in a suitable medium, such as oil or water. This sudden cooling transforms the spring’s microstructure, leading to increased hardness and improved mechanical properties.
• b) Tempering: Following quenching, tempering is performed to reduce the brittleness caused by the hardening process. The springs are reheated to a predetermined temperature and then slowly cooled. This step helps achieve the desired balance between hardness and toughness, ensuring optimal performance under varying loads.

3. Our Commitment to Excellence:

At Chinacustomspring, we take pride in our expertise in compression spring manufacturing and surface treatment. As a professional compression spring manufacturer in China, we offer a comprehensive range of surface treatment options, including heat treatment hardening, to cater to our customers’ diverse requirements.

• a) Customization: We understand that each application demands unique characteristics from compression springs. Our experienced engineers work closely with clients to determine the most suitable surface treatment method for their specific needs, ensuring optimum performance and longevity.
• b) Quality Assurance: We adhere to stringent quality control standards throughout the manufacturing process. Our advanced testing facilities and rigorous inspection procedures ensure that every compression spring leaving our facility meets or exceeds industry standards for durability, reliability, and performance.

Choose Chinacustomspring for your compression spring needs, and experience the difference that our expertise and commitment to excellence can make.

Request A Quote for Compression Springs

We can make a lot kinds of compression spring which made in different shape or material . It’s simple to work with us. Customer only have to offer us drawing or sample, even rough idea is all right. we will quote you best price and offer good quality.

Please provide following information to get a free for custom compression spring:

1.Type of Material:
2.Wire Diameter:
3.Outside Diameter: and Inside Diameter:
4.Free Length:
5.Number of Coils:
6.End Type:
7.Rate:
8.Wire Direction:
9.Finish:
10.Quantity:
11.Other information that is not required but helpful if known

Please refer to the deign of compression springs ,which will be useful to make a custom-made springs

Other types of springs we manufacturing

• Circlips
• Torsion Springs
• Extension Springs
• Die Springs
• Wire Forming

You can get more information for spring from wiki