A constant force spring is a roll of pre-stressed strip which exerts a nearly constant restraining force to resist uncoiling. The force is constant because the change in the radius of curvature is constant. This is true if the change in coil diameter due to buildup is disregarded. Long extension capabilities, constant torque, and a virtual absence of intercoil friction have led many designers to specify constant force springs in such applications as brush springs for motors, counterbalance springs for window sashes, and carriage return springs for typewriters. Constant force springs are used to drive mechanisms for timers, movie cameras, and cable retractors. It is recommended to leave at least two wraps of the spring coiled at all times during use. The cycle life is approximately 2000 cycles.
We specialize in the production of Constant Force Springs that can be used for several applications, many times as motor or power springs, but are found most often in POP (point-of-purchase) displays and other product merchandising units. Some examples include electronic, cosmetic, pharmaceutical, and food or beverage displays.
Custom Constant Force Springs
We produce several springs with standard end fittings; however, if none of these suit your needs, we are happy to custom design an end fitting for your specified application. From a few springs, to millions, we ship in any quantity and offer some of the fastest lead times in the industry.
If you would like to request a free sample kit to test our Constant Force Springs for your design or application or coordinate shipping an example of your existing trays and product for us to assist in making a recommendation, fill out our Custom Quote form.
Select request a quote to send us your specs or configure a spring.
Constant Force Springs Manufacturing
MW is a leader in the spring manufacturing industry. We provide standard and specialty processes to ensure your requested product meets your goals for quality and aesthetics. Some examples include heat treating, CNC machining, stamping, and laser etching.
Width tolerances for constant force springs are dictated by strip tolerances, and diameter tolerances are determined by storage and output drum tolerances. Torque tolerances are ±10% and I.D. tolerances are ±25%. Strip thickness and length should be considered reference dimensions.
Not sure where to start? Our highly trained staff of engineers and specialists are always on hand to assist with design, development, and manufacturing.
Most Constant Force Springs are made from Stainless Steel; however, if your specific application requires a specialty metal or a finish that is not listed here, we are happy to work with you to customize a product that suits your needs.
We stock several material widths and thicknesses and can produce constant force springs in the below specifications.
Wire Specs & Size for Coiling
- Strip Widths: 0.100” – 2”
- Thicknesses: 0.003” – 0.031”
- Lengths: 12”- 60”
Direction of Helix (Wind)
We can configure your variable force springs in either a left or right wind configuration to suit your specific application.
We produce springs in several end configurations. Some of the most popular requested end configurations include the below; however, customizations can be accommodated as well.
- Round Dome
- Small and Large Eyelet
- Reusable & Self-centering Magnetic
Our variable force springs can be manufactured with a selection of commonly requested services.
- CNC Machining
- Heat Treating
- Laser Etching
- Metal Stamping & Forming
Quality Standards & Certifications
At MW, we pride ourselves on creating quality products that meet or exceed industry standards. Not only do our facilities perform rigorous quality assurance testing to your specified ranges, but we also maintain several key certifications to ensure that only the best products are shipped to you.