Who says flat steel springs are dated? Genius artist and inventor Leonardo da Vinci (1452–1519) used flat steel resources in many of his creations, many of which were ahead of their time. Flat steel springs were a part of many of his inventions, including the self-propelled cart and the first iteration of a helicopter, and yet, today, flat springs are part of our lives.
Flat steel springs may often be overlooked by their round wire counterparts, but we will explore more about them to give them the recognition they deserve.
Types of Flat Springs
There are several types of flat springs, from cantilever, leaf, and flat coil to volute and Belleville, but we will focus on constant force springs, which are used where a consistent force is needed over a range of movement.
Why Use a Constant Force Spring?
Constant force springs, like our Conforce Spring, offer high-force output with small space requirements. They also provide long linear reach with minimal force buildup and store energy indefinitely when extended, making them ideal where constant force is needed.
They are applied in many industries and fields, such as aerospace & defense, medical devices & healthcare, and more. Some common applications include:
- Counterbalancing: Ideal for windows, shades, hospital tables, X-ray machines, industrial equipment, and military tank seats.
- Push or Pull Mechanisms: Integral to staple and nail guns, surgical staplers, drug delivery devices, motor brushes, toasters, cupholders, fire dampers, retail displays, and more.
Constant force springs are also used in smart device mechanisms, wearable technology, and furniture and ergonomic products to facilitate smooth and effortless adjustments.
Key Design and Ordering Considerations
If you are considering a constant force spring, several factors are crucial for optimal performance:
- Material Selection: The most common material is type 301 stainless steel. Texture-rolled high-carbon steel can be used when a lower cost is required for high volumes; Inconel 625 and Elgooly are utilized for the most demanding applications. Material thickness generally runs from .002” to .031”, and tensile strength ranges from 270,000 to 310,000 psi.
- Cost: 301 Stainless is the most commonly specified material. Inconel and Elgioloy are significantly more expensive than texture-rolled high-carbon.
- Volume Timing Needs: Estimate the number required and production timeline. Define critical characteristics, tolerances, and packaging needs.
- Force & Diameter Relationship: As the spring diameter increases, the spring force decreases, and cycle life increases due to lower stress.
- Testing and Inspection: Design aspects like coil diameter, end detail, length, load or force, drum size and mounting, and workmanship are typically tested, inspected, and matched to the customer’s requirements.
Constant Force vs. Constant Torque: What’s the Difference?
Constant Force Springs provide a linear extending/retracting force. In contrast, Constant Torque Springs, like our Contorque Spring, offer high amounts of torque with small space requirements and can be designed to produce a constant torque or a positive or negative gradient output.
Conclusion
Whether we see them or not, flat springs are in our day-to-day lives, enhancing functionality, safety, and convenience in numerous everyday applications. If you need to work with these, always choose high-quality, well-designed products. Choosing the right supply partner, such as Vulcan Spring, can help you achieve effortless results. At Vulcan Spring, we go “Beyond the Spring” to support your engineering innovations with expertise and dedication.
