Whilst they’re easy to manufacture and also relatively cheap to produce, tension springs can generally be found to possess a high level of reliability.
Within industrial systems, these small components take on a more critical function, as the failure of any part of the system will result in a disruption to productivity. Often required to operate under more extreme and demanding conditions and to a higher degree of accuracy, it is therefore, vital that even these peripheral components are of premium quality.
Understanding the Basics
A tension spring may be the exact opposite of the commonly conjured image of a mechanical spring, but they play an important role in the design of many mechanical systems.
A very simple form of the extension spring can be seen in the workings of a rubber band, as this effectively works on the very same principle of manipulating a directional force. Used to keep two objects together, unlike a compression spring, which primarily is used to maintain a distance between parts. Tension springs are also used to retain shape and structural integrity within materials.
The load on the spring is created by stretching rather than compression and so extension springs often have small hooks or loops at either end, which are used to attach the spring into position. With many differing applications for these springs, there are also many different types of connectors, which can be built onto the ends of the springs, such as:
- Coiled in attachments
- Extended hooks
- Screw in connectors
- Side loops
- Half hooks
- German loops
- Side hooks
- English loops
However, along with the many variations of extension spring that exist, they all operate in the same fundamental way of capturing and redirecting an applied force.
Tension Springs in Practice
A common example of this is in the workings of a trampoline, which uses tension springs around the perimeter of the “bed” or active area of the trampoline to both capture the inertia of the impact. It then returns the force with an equal and opposite reaction that returns the structure to its starting position.
A variation of this idea can be seen with the garter spring, which comprises of one spring that is connected circularly to itself, forming a bracelet shape, which can be expanded in circumference with the appliance of pressure. These type of tension springs are ideally suited for systems which use pressurized liquids or gasses, as they offer a simple solution to valves which are needed to quickly and effectively react to the conditions they’re placed under.
Another important utilization for these springs is within the cylinders of pneumatic and hydraulic engines. These designs typically need to be very hard wearing, as they can be placed under considerable amounts of stress due to being continuously in use over a large time period, meaning that they need to be durable enough to comfortably perform to a high standard over many thousand, often millions of repetitions.
The actual lifespan of these components are highly reliant upon the conditions they’re placed under and as such they can vary hugely between different applications. A good understanding of the specific working environment is key to preserving the integrity of the equipment for as long as possible.
Further Applications within The Industrial World
Further to acting as hinges for closing hatches, doors and returning something to its original position, the tension spring is also commonly found in the make-up of large-scale switches and circuit breakers.
Another common application for this type of spring is in its use to measure the amount of force being applied across a system. This can be easily represented by the spring-loaded weighing scale, which works under the same principle of measuring the distance that the spring extends to determine the size of the applied force upon it.
Tension springs are therefore manufactured to produce a specific amount of force that makes them suitable for the working conditions to which they are intended. This can lead to many choices in the construction of the simple spring.
Considerations in Design and Performance
Not only is the amount of force that a spring produces carefully crafted in its production, there are many other variables which need to be factored into the manufacturing stage which has an effect on performance.
The way in which force is exerted onto the spring is actually split into two actions. Firstly, there is the amount of force required before the spring begins to extend, which is known as the initial tension. Secondly, there’s the actual amount of force, or load, that the spring can handle safely without deforming or fracturing the form of the spring.
Both of these forces can be manipulated in the design stage by altering one or more of the following factors:
- Coil length
- Deflection capabilities
- Stress levels
- Diameter of wire
- Diameter of coil
- Material used in construction
- Additional materials used as coating
- Environmental concerns towards fatigue and reliability
The Need for Expertise
Spring experts don’t need to be experts in every field of engineering, as by understanding the conditions placed upon these peripheral components, they can not only comprehend the spring but also how it will be able to function to its peak capacity with a system.
As the physical form variables of many springs are constricted by the mechanical needs and requirements of the system that they fit into, this makes both the materials used and the quality of the production increasingly important factors. This is one reason why it is imperative to choose a spring supplier that is both knowledgeable and trusted throughout the industry, over potentially cheaper but less reliable alternatives who are unable to conduct capability studies, especially when looking for customized, bespoke parts.
With a high-level of understanding in the field of springs, not only will you receive a part that is more than fit-for-purpose, you will additionally have a source of information that can be used to potentially increase the lifespan of the parts and avoid unnecessary operational downtime due to system failure.