Everything You Need to Know About Spring Force

What is spring force and how does it affect a spring’s usage? This is crucial to know, especially when springs are part of everyday applications. Read further.

Everything You Need to Know About Spring Force -

Springs come in a wide range of sizes and shapes. But irrespective of the way they look, every spring generally works the same way. Each spring you come across stores and release tremendous energy, and this makes it an elastic item. Spring design/manufacturing, therefore, depends principally on an in-depth understanding of springs and their physics.

Understanding the physics associated with springs enables manufacturers to carefully and correctly predict springs will act in real-world scenarios. Springs are generally simple mechanisms that – more or less – behave in a predictable manner. But then, you need to know precisely what to expect when using springs.

In this post, you will learn everything you need to know about spring force, a vital component that helps increase your understanding of the physics of springs.


Spring Force/Spring Constant

Spring force is usually measured by the spring rate or spring constant. This, in turn, is measured by the pounds of force it takes a spring to travel at least one inch of compressed distance.

The spring constant is a constant amount of force increase per the increase of distance covered or traveled. In other words, the force is directly proportional to the distance of travel. The spring constant is used to determine the precise amount of force required to deform a spring. And it is determined based on the following parameters:


  • Free length: This refers to the length/size of the spring when a force does not stretch it, i.e., when it is at rest.
  • Coil diameter: This is the diameter of each coil and measures the overall tightness of the coil.
  • Number of active coils: This refers to the number of coils that are free to contract and expand.
  • Wire diameter: This is the diameter of the wire the spring is made of.


The spring’s material also plays a crucial role in the determination of the spring constant as well as other physical properties of the spring. The higher a spring constant is, the stiffer the spring, and vice-versa.

The SI (standard international) unit of measurement for spring constant is Newton/meter. However, in North America, the spring constant is generally measured in pounds/inch.

If you have to work on a compression spring design, you need to ensure that the spring’s dimensions give you the right amount of force. Of course, you may have to worry a little bit about the spring dimensions and whether or not they are right.

If the spring is too weak, it may travel and compress beyond the required distance. And if it is too strong, this might not allow your spring to travel the required distance. Therefore, you need to get the dimensions down.

And then, you should take a look at your working loads in order to start making necessary adjustments that will match the required spring constant/force.

What are working loads? Working loads refer to your required loads at loaded height. The loaded height refers to the length of a spring after traveling a particular distance. For instance, let’s say you want your spring to compress 0.30 inches under a 5-pound load while its free length is 0.9 inches, your loaded height is calculated using the formula below:


Loaded Height (LH) = Free Length (FL) – Distance covered (traveled)

LH = 0.9 – 0.30

LH = 0.60

In order to calculate the spring force/rate, the following formula to use is as follows:

Rate = L/distance traveled. i.e.

Rate = 5/0.3 = 16.66

This is the spring force/rate of the spring.


Hooke’s Law: The Vital Discovery

To enhance your understanding of spring force, it is essential to go back in time. Before Newton published his famed laws, another brilliant English scientist or physicist known as Robert Hooke (1635-1703) carried out a few experiments.

In one of them, he suddenly discovered that the extent of deformation of an object was directly proportional to the force applied in order to deform the object. However, the object must have a particular property or attribute known as ‘elasticity.’ And he ended up dropping his ever-popular law known as Hooke’s Law.


Hooke’s Law

Hooke’s law is incredibly easy to remember, write, and even work with. The law says that the force required in order to keep a spring – or any other elastic item – from being deformed further is proportional to the distance the object or spring as already deformed.

In simple terms, F = – kx. where ‘k’ is known as the spring constant and ‘x’ is the length – or extent – of deformation. And this spring constant is different for different springs, as expected. Hooke’s law is in play in several tools and even in various aspects of life. You will find the law in action in shock absorbers, archery bows, and even bumpers on vehicles.

Hooke’s law applies in two directions of deformation in springs, i.e., during the stretching and the compressing processes. And although there are several exceptions to Hooke’s Law, the one that stands out has to do with the spring’s deformity.

An extension spring can be extended so far that it ceases to obey Hooke’s Law. In other words, the spring does not regain its original shape. The point at which this happens, i.e., the length via which a spring stops conforming to the law, is referred to as the spring’s ‘elastic limit.’


Why Spring Force Matters for Spring Design/Manufacturing

Manufacturers that make springs must know how the springs will behave. Of course, the spring used in a ballpoint pen will not work for truck suspension.

Every spring design characteristic plays a crucial role in determining the practicable applications for any given spring. And no manufacturer makes wild guesses when dialing in the setting on their spring coiling equipment.

Having an in-depth understanding of springs, the physics of springs, Hooke’s Law, etc., manufacturers can efficiently create the perfect coil for the spring, based on the design.


Wrapping Up

As you can see, the importance of the spring force can never be overemphasized. Spring force is key when it comes to producing top-notch springs for the items we use every day. Manufacturers don’t joke with this vital component when manufacturing springs. And this is why it is equally important to work with a top spring manufacturer like KB Delta.

KB Delta provides high-quality springs for everyday objects and tools such as a ballpoint pen, etc. Get in touch today, and you will be glad you did!

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