How are springs made? This is a great question with a lot of factors to it. Here’s what you need to learn.
Mechanical springs are ubiquitous and the most straightforward machines in today’s world. From consumer products – such as door handles, beds, etc. – to heavy industrial machinery or equipment, springs are practically everywhere, as long as a mechanism is involved.
Springs are coiled devices that store mechanical energy. They provide compression and tension in a wide variety of applications. They have been in use since the 1400s, i.e., practically 600 hundred years ago.
But most people do not know how springs are made or even what they are really made of. Understanding how these mechanical devices are made, what they are made of, etc., is fascinating.
Let’s check out how springs work, how they are made, the key definitions you should know, and a lot more.
How Springs Work
Springs generally work based on a popular law of Physics known as Hooke’s Law, created by Robert Hooke, a British physicist. The scientist published his well-documented ideas on springs in the 17th century, specifically in 1678.
According to Hooke’s Law, the force a spring exerts is directly proportional to its equilibrium or initial position displacement. Expressed mathematically,
F = kx, where ‘F’ is the force the spring generates, ‘k’ is the spring’s stiffness, i.e., a constant. The latter is a function of the coil’s thickness, the material’s properties, as well as the number of turns in the coil. It is also a function of the coil diameter and the free length of the spring.
The unit of measurement for the spring constant is Newton/centimeter or Newton/meter, i.e., the force unit divided by the length unit.
When springs follow Hooke’s Law, they behave in a linear fashion. This implies that the force the spring generates is a linear function of the deformation or displacement from its neutral position.
Every material has what is known as an elastic limit. Any material stretched beyond this limit will lose its springiness and remains permanently deformed. It will no longer regain the capability to return to its original shape and size.
Springs can also be stretched far enough to exceed their elastic limit. When this happens, the springs will stop following Hooke’s Law.
What Are Springs Made of?
Springs are generally made of a wide variety of metals conveniently configured into round wires. These metals come in 3 categories:
1. Stainless Steel
Stainless steel is a relatively common type of wire used for making metal springs. This material’s unique characteristic is its ability to withstand corrosion.
Stainless steel comes in several varieties, and each type has different levels of hardness and elasticity. Stainless steel springs are more commonly used in manufacturing devices employed in the medical field as well as outdoor applications.
2. Steel Alloys
Steel alloys are common choices for springs. Chrome silicon – which is a steel alloy – is commonly used in large springs.
Although steel alloys can withstand incredibly high temperatures, they are too prone to corrosion to be of much use in moist environments.
3. High Carbon
Springs made from this material are the most common due to their versatility and relative inexpensiveness. Types of high carbon wires include hard-drawn wire, music wire, etc.
The hard-drawn wire is commonly utilized in commercial products, while you will discover music wire is primarily used in mechanical tools.
However, the hard-drawn wire doesn’t perform impressively well in corrosive and high-temperature environments. So, there is a limit to the type of use it can be subjected to.
But what is the best material for manufacturing spring? The answer to this question is that it depends entirely on the primary application. The best material for making springs depends on several factors. This includes the cost of the material, its physical properties, etc.
Metals are, in most cases, the commonly used materials for making springs. But this material can’t be used for making some springs that have unique applications.
For instance, some spring types – e.g., cylindrical non-coil springs – are made with urethane and rubber. Similarly, a Torsion Spring can be made up of rubber and metal. Such torsion springs can be used for motor bases, impact beds, chain tensioners, etc. Ceramic is also developed for coiled springs used in high-temperature environments or applications.
However, these are highly specialized uses of springs. Most springs employed in the majority of equipment you see today are manufactured using metals.
How Are Springs Made?
Springs are generally made of hardened spring steel, or other materials, depending on their application. The material can be pre-hardened before the formation of the spring or hardened following spring formation.
Helical springs are typically any spring manufactured from wire or bar stock and formed into a helical shape. The long stock wire is employed for this purpose. It is fed into a machine known as an auto-coiler in order to produce this spring type.
If a smaller run is set up, the wire stock may be coiled on a lathe (head online to find the best metal lathe for your intended purpose), though several safety concerns must be considered here. This is because spring wire may uncoil dramatically if the machinist loses control or is not tied down firmly.
This uncoiling characteristic can be hazardous to anyone nearby, especially if a heavy gauge wire is the parent material for making the spring.
Auto-coilers are machines that force spring wires into spiral shapes. It shares the same name with the automotive auto-coil transmission, but it is not the same device.
Auto-coilers used in making springs are adjustable so that users can readily alter the coil length, tension, and number. These machines employ rollers that feed the spring wire right through headers. The headers, in turn, quickly spin the spring wire around a cylinder.
This quick-spinning action forces the spring wire to adapt into a coiled, helical shape and maintains it. The auto-coiler eventually ejects the coiled spring and gets ready to take on the next piece of spring wire for the same process.
However, a different type of spring called the ‘leaf spring’ is not formed this way. First of all, the machinist shears a flat bar into shape and punches a collection of these bars together.
Several machines trim these bars in order to do away with extra metal as well as to taper the ends. The spring undergoes heat treatment in order to harden the steel. Other treatments – such as painting finishes, etc. – are carried out in order to match the finished spring to several pre-determined visual-specific requirements.
Types of Springs
Different types of springs are manufactured today, and each one is designed for a particular application. Each spring also has different energy storage management, which is ideal for its unique application.
Some of the typical spring types today are:
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- Compression
- Torsion
- Constant force
- Drawbar
- Garter
- Volute
- Belleville
- Air
- Flat
- Gas, etc.
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Conclusion
Springs are simple machines that play crucial roles in a wide variety of applications in the modern world. Knowing how these devices are manufactured, how they work, the materials they are made of, and the different types, will help determine the actual application they are needed for.