1. Compression Springs - What Are They? How are They Made? By - St. Mary's Spring Company

2. Introduction to Compression Springs • Compression springs are a type of springs, which get compressed after applying an external force on them. Several helically formed coils together make a compression spring. • These helical coils have pitch in between. This allows the spring to gain its original form after the applied force is removed. Compression springs are the most widely used springs in a variety of applications.

3. Materials Used in the Construction Compression springs can be manufactured in a variety of materials, such as: • Non-ferrous Alloy Wire • High Carbon Spring Wire • Stainless Steel Wire • Carbon and Alloy Wire • Alloy Steel Wire • Hard Drawn Wire

4. Key Design Factors For designing a compression spring, following factors are required to be considered: • Dimensions and Material Type of the Spring – This includes determining parameters, such as the outer diameter, inner diameter, free length, and wire diameter of the spring. Also, to be considered is the type of material used for the spring. You can select from different materials, such as stainless steel 302 A313, or music wire ATSMA228. While selecting the material, you should also take into account the working environment of the spring. • Force and Elasticity – You need to know the spring rate or spring constant in order to determine the spring’s force. Also, the elasticity of the spring is or extreme importance while designing a compression spring.

5. End Configurations and Body Shapes End Configurations and Body Shapes : • Closed and Squared Ends • Closed and Ground Ends • Open Ends • Double Closed Ends Similarly, the spring can have a variety of body shapes, which include: • Hourglass Compression Springs • Conical Compression Springs • Straight Cylindrical Compression Springs • Barrel Compression Springs

6. Calculations To design good quality springs that are suitable for specific applications, you need to have certain formulae. Following are the most important formulae required in designing and manufacturing compression springs: • Spring Rate: The spring rate is calculated by dividing the spring’s load by the distance travelled. It is given by k (Spring Rate) = L (Spring’s Load)/T (Distance Travelled) • Mean Coil Diameter: There are two ways in which you can calculate the mean coil diameter of a compression spring • (Outer Diameter + Inside Diameter)/2 • Outer Diameter – Wire Diameter • Spring Constant: Spring constant K is calculated by the following formula: K = Gd4 / 8D3N Where, G = Shear Modulus of Material d = Wire Diameter D = Mean Diameter N = Active Coils Double Closed Ends

7. Designing Tips As we come towards the end of the presentation, here are some quick designing tips that would help you design the most suitable compression springs for your applications: • The count of the coil should only be the reference, if spring rate is specified. • The spring index of the compression spring should always be in the range from 4 to 25. • The applied force (which is denoted by P) should be specified. The total distance travelled by the spring should be somewhere between 15% and 85%. • You should notify the manufacturer in case of any close fitting assemblies or parts.

8. Thank You!! Hope you liked the presentation. For more information, click here Contact: 800-330-2460 Email: smsc@windstream.net