Springtelligence

Learning about springs

The design and manufacture of springs touches every aspect of mechanical engineering. Many innovations in the automotive, aerospace, agricultural and medical industries, and more generally in our everyday lives, would not have been possible without springs. Yet very little time is devoted to spring engineering in our education systems. Springtelligence is your tutor to understanding the world of springs.

Home | Springs | Springtelligence

Spring Terminology

The technical spring glossary

What is creep of a spring? How many active coils should we count? What is the lateral deflection of a spring under stress called? These are all questions that are sometimes difficult to answer without precise and shared terminology. This is the whole point of our glossary: to provide you with a clear and structured reference on the entire vocabulary of spring manufacturing.

Here you will find definitions of the most important terms related to mechanical spring engineering as well as the associated calculation methods, tolerances and standards. Each entry is designed to help engineers, buyers, and technicians use a common language, whether in a design, manufacturing, or procurement context.

Our glossary is available in three languages: English, French and Chinese. In this way, it helps to facilitate exchanges in international projects. Whether you are an expert in the field or simply looking for terminological clarifications, this glossary is designed as a practical, educational and evolving resource.

Access the glossary

Spring tutorials

Engineering knowledge resource

Springtelligence is a set of knowledge resources and learning materials designed to help the understanding of spring design. It has been developed by engineers at CGR's UK subsidiary, JBSprings. The knowledge base consists of a series of video tutorials covering a wide range of technical aspects related to spring design and manufacturing.

Springtelligence as well as CGR's STRAIN spring research and development laboratory are examples of CGR's commitment to educate by sharing knowledge, in line with our maxim “form your world”.

Conical springs

Conical springs are a specific type of compression springs. Conical springs are coiled in increasing or decreasing outer diameters thus creating a coned or tapered shape. Conical springs enable a reduced solid height as the smaller coils will fit partially, or sometimes fully, inside the larger coils below.

Tension spring end types

The five commonly used tension spring end types are:

machine loop,
crossover loop,
side loop,
extended ends,
coned ends.

Hooks and loops are the two basic end type options used with tension springs. Loops are fully closed while hooks have a gap.

CGR-international_tension_spring_end_types

Common mistakes in torsion spring design & use

Torsion springs are a type of flat spiral coil or helical shaped spring. A torsion spring rotates with increasing loads. There are four key torsion spring design flaws that can affect the performance of a torsion spring:

incorrect direction of operation,
inside diameter too small,
body length too large,
overstressed.

CGR-international_common_mistakes_in_torsion_spring_design_and_use

Torsion spring leg types

The leg of a torsion spring is a lever. There are four main torsion spring leg types, determined by the way the legs leave the spring body:

tangential,
axial,
radial,
radial over-centre.

Measuring a tension spring using a digital vernier calliper

The dimensions of a tension spring, such as the spring's wire diameter, will determine its performance. Use of a digital vernier calliper is recommended to measure tension springs accurately.

CGR-international_measuring_a_tension_spring_using_a_digital_vernier_caliper

Measuring a compression spring using a digital vernier caliper

The dimensions of a compression spring, such as the spring's wire diameter, will determine its performance. Use of a digital vernier calliper is recommended to measure compression springs accurately.

Initial tension

The initial tension of a tension spring is equivalent to the force required to extend a spring to the point where it starts to elongate and gaps appear between the coils.

Tension spring rate

The rate is the strength of a tension spring as defined by Hooke’s law. Hooke’s law states that the elongation of a spring is directly proportional to the force applied. The proportionality factor is called the spring rate or spring constant.

Counting coils on a tension Spring

Counting coils on a tension spring is the same as counting coils on a compression spring. To count spring coils, it is important to understand what is and is not, an active coil. The type of ends on a spring will make no difference to the number of coils.

Loads at length for a tension spring

The loaded length is the length of a tension spring once a certain force (or load) has been applied to it. If too much force is applied to the tension spring it will no longer contract, therefore breaking the spring.

Measuring the length of a tension spring

This video explains how to measure the free body length, the overall body length and the working length of a tension spring.

Measuring diameters of a tension spring

This video explains how to identify and then measure the wire diameter (d), outside diameter (OD) and mean diameter (D) of a tension spring.

CGR-international_the_diameters_of_a_tension_spring

Spring Tolerances

Tolerances refer to the acceptable variation that will allow a spring to function. Springs require larger tolerances than machined parts.

Compression spring rate

The spring rate, or spring constant, is the amount of force it takes compress a spring by a certain distance. The rate is defined by Hooke’s law. This video shows how to calculate the rate of a compression spring.

Loads at length for a compression spring

The loaded length of a compression spring is the length once a certain force (or load) has been applied to the spring. The video shows how spring loads work and how they are derived from spring rate.

Outside diameter expansion of a compression spring

When a compression spring is loaded, the pitch of the spring is reduced and the outer diameter of the compression spring is enlarged. Sufficient tolerance must therefore be provided.

Compression spring end types

There are three different kinds of end types of a compression spring:

open and unground,
closed and unground,
closed and ground.

CGR-international_compression_spring_end_types

Active and dead coils of a compression spring

Compression springs can consist of active coils that can take stress or loads and dead (inactive) coils which cannot support any load. The inactive or dead coils are usually the last closed coil on each end of the compression spring.

Spring winding direction

If two compression springs have to operate one inside the other it is important for them to be wound in opposite directions. This will prevent the two coils from getting entangled.

Gap and pitch of a compression spring

This video will show you the gap between two adjacent coils of a compression spring and the simplest method of measuring the pitch on a compression spring.

Diameters of a compression spring

This video demonstrates how to identify and then measure the wire diameter (d), outside diameter (OD), inside diameter (ID), and mean diameter (D) of a compression spring.

Measuring compression spring lengths

The length of a compression spring is defined by its free length, loaded length and solid length. This video show how to measure the lengths of a compression spring.

CGR-international_measuring_the_length_of_a_compression_spring

How to count coils

Counting the coils of a spring is one of the most frequently misinterpreted concepts in spring manufacturing. Learn how to count coils correctly.