Technical Springs - An Engineer’s Guide

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What does the term “technical springs” mean exactly? Which types of metal springs are referred to and for which force states and applications are they used? Jürgen Mugrauer explains all

The term technical springs includes all metal springs that are used in technical applications. The special property of technical springs is their reversible change in shape under load. This is made possible by the special shape and the spring material used. Technical springs are used in almost all sectors, for example in mechanical engineering, electrical and medical engineering, the food industry and aerospace, where they fulfil a wide range of tasks.

Technical springs – such as form springs, flat springs, flat form springs, contact springs, compression springs, tension springs and spiral springs – are used as storage elements, measuring elements, vibration elements, resting elements and bearing elements.

Spring Technique

The basic technology of all technical springs is based on their ability to store potential energy as tension energy and to convert this into kinetic energy in a controlled manner and vice versa. Below are a few examples of the force conditions for which technical springs are often used:

Restoring force. The spring force is used as a counterforce to return the moving mass to its previous rest position. This restoring force is the most common application of technical springs and is provided to the same extent by form springs, flat springs, compression springs, tension springs and torsion springs.

Adhesive force. In non-positive connections , lock washers and spring washers provide compressive and adhesive forces that counteract unwanted loosening, mostly of screws and nuts.

Balancing force. When other components change shape, size or position, technical springs are often used to compensate or to maintain the electrical connection. Depending on the task, form springs, flat springs, contact springs, compression or torsion springs
are suitable for this.

Weight force. The spring is used to evenly distribute the load between bodies. The best example is the innerspring mattress, which provides this weight with special conical compression springs.

Driving force. By preloading a technical spring, energy is stored, which is then released when it is relaxed and drives mobile devices. Spiral springs, for example, are used to drive mechanical clocks or to roll up flexible dog leashes.

Vibration and damping force. The technical spring deforms as it absorbs kinetic energy from incoming forces or impacts. When the mass oscillates, this kinetic energy is converted back into potential energy. Leaf springs, for example, ensure that the load is protected from the forces and impacts that act on it.

Spring development

The goal when developing a new technical spring is to find a spring for the given application that fits perfectly, taking all circumstances into account. Function, shape and dimensions must be selected in such a way that the technical spring optimally fulfils the required spring work. Various factors play an important role in spring development – for example, which task the technical spring must fulfil, which spring movement is desired, how large the available installation space is and which connection components are available. In addition, there are properties and special features from the overall construction and from the operating conditions. Other considerations include corrosion resistance, electrical conductivity or to determine the most economical production possible or the basis of the spring construction. In general, the following requirements for spring development must be brought together for technical springs.

Task And Function

What is the technical spring used for (medical technology, food technology, electrical engineering, etc.) and which functions – such as the state of force, development of force (spring characteristic) and any additional functions (electrically conductive, non-magnetic, insulating, acid-resistant, etc.) – are required?

With regard to the installation situation and installation space, engineers must ask how is the force introduced (compressive, tensile, torsional or bending stress) and what installation space is available for this?

Determining feather type and feather shape is another requirement. Which spring type is suitable for the task and with which spring shape can this be implemented in the existing installation space?

Required forces and spring deflections should also be considered. Which spring forces are required for certain spring deflections or lengths?

Operating temperature and environment are other key considerations. At which operating temperature and in which environment (air, salt water, engine oil, etc.) is the technical spring used?

Finally, the type of load and service life should be determined. What is the type of load (static constant load or dynamic load with changing loads and lifting stresses)? For what total service life should the technical spring be manufactured?

Jürgen Mugrauer is communications manager of Gutekunst Federn

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