Our teams are expert extension spring manufacturers offering hot coiling and cold coiling manufacturing capabilities across some of the most advanced spring technologies in the industry.
Our hot coiling facilities can manufacture extension springs up to 65mm wire diameter with our cold coiling starting at 3mm wire diameter.
Advanced CNC coiling and grinding machines deliver quality, accuracy and the best production run rates and efficiencies across an extensive wire range.
In-line shot peening facilities improve a component's shelf life and fatigue performance and large-scale, fully automated powder coat lines offer a zinc phosphate coating option in advance of powder coating, delivering 1000 hours of corrosive salt spray resistance.
Investment in spring technology is crucial and we have recently secured the largest Wafios cold coiling machine in the world, guaranteeing us as leading heavy-duty extension springs suppliers.
We hold the largest stock of chrome silicon in the world and work with carbon steels, low and high alloyed steels which enables our engineers to source the right material for the right application and work environment of your tension spring.
When considering industrial tension springs we need to evaluate the tension spring material for chemical composition, surface properties, tensile strength and wire diameter.
Our material scientists are leaders in their field and are on hand to consult with our engineers on the properties of all our metals including:
The Lesjöfors Heavy Springs teams are positioned to consult on the benefits of each extension spring material for the maximum performance of your application. Our processes are adapted according to specific extension spring material needs, including heat treatment, shot peening and pre-setting. Our materials page has more information and advise on surface treatments for corrosion resistance and aesthetics.
Customer consultation enables us to work out how to calculate spring tension for your product by using a tension spring design calculator. We also analyse what material would work best and if the spring requires loops or hooks. The maximum initial tension that can be put into a tension spring during manufacturing is limited and therefore it is crucial that we understand the parameters of your extension spring so that we can optimise its use in your product. Our innovative teams deliver exceptional engineering expertise and are solution providers, custom designing your spring to your specifications.
To achieve the best results in developing your tension springs, our engineers ask a number of questions:
There are occasions where none of this is known, where customers are not sure of the parameters of their coil spring needs and that’s where our extension spring engineers investigate further, discovering the customer’s tension spring purpose.
Tension spring design often goes through many cycles to guarantee the right design for the right purpose. Designing prototypes that evolve as your product design evolves and manufacturing material samples before full production runs, is all part of the customer care and product service culture we believe in. Our engineers are leaders in their field, ensuring the extension spring performance achieves maximum success.
Due to the nature of the design of an extension spring, their application is often found in environments where they are needed to absorb energy to create a resistance to a pulling force.
Across the world, many people start their day with a tension spring. They might pull back the curtains using a spring tension curtain rod or access their car via garage door tension springs and if they cycle to where they need to go, bike brake spring tension will get them there safely.
If going to the office, you’re likely to access the building using a door tension spring and sit at your place of work on chair tension springs.
The expansion spring simply says what it does; it expands to a required length and provides a return force to the components it is fitted between.
Used across domestic and industrial applications, our tension springs are installed across every function from garage doors to canopies in football stadiums to heavy plant machinery.
As helical coiled springs they might seem similar. However, the big difference is how they absorb force. Compression springs are made to keep components apart and tension springs are designed to keep components together – compression springs absorb force when compressed and an extension spring returns a force when stretched.
Any lever-based mechanism requires a tension spring. Take a look at our section on what are tension springs used for. Garage doors, curtain rods and trampolines are classic examples of how to use a tension spring.
Once we’ve designed, manufactured and dispatched your product, the install element is individual to need, and we suggest you visit YouTube to discover hands-on applications of tension spring installs.
A digital vernier caliper is the most effective tool for this. Start by measuring the outside coil diameter. It is difficult to secure an accurate reading for the inside coil diameter with the caliper because of the hook/loop ends.
Use the caliper to measure the wire ends in line with the axis and at a 90 degree angle from the axis, and use the average of these two dimensions to secure the wire diameter.
Then measure the free length - the length of the spring inside the loops and the length of the spring body and the length of the overall spring (from the end of the hook/loop to the other). Find out more about our spring terminology.
We are world-leading heavy duty spring manufacturers, delivering the greatest expertise in compression, torsion and tension spring manufacturing.
Delivering impact to every industry, we guarantee spring solutions that will optimise your performance and success.