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Springs can be created from various designs to take care of a need. Where it will be used plays a role in the right option. All springs will become stressed when they are under a load. The spring in place must be able to take on the amount of stress with that particular setup. Otherwise, the stress will cause the spring to become deformed. It won’t keep the original design and it won’t work as it should.
Springs can be created from a wide variety of materials. The specific type of material will influence the overall strength of the spring. It will also determine the amount of stress it can handle. Keep in mind, when the spring wire is heated, that is also going to modify the form of it.
One of the common types is compression springs. When they are at full compression, the coils are going to touch each other. The diameter of the wire multiplied by the number of coils can’t be greater than the amount of space available. Otherwise, the spring is going to stop the motion in play, it will be a mechanical stop.
Any time a compression spring will be used in an environment of high-temperatures, it needs to be longer. A common use under such conditions is within an engine design. The longer length is going to ensure the compression spring is able to work properly, even with the extreme heat. In this scenario, the spring will assume the load and get shorter. At the same time, the active coils will have an increased diameter. This can be a challenge when the spring is in a confined area.
Pay attention to the designated extension limit on extension springs. If they are used beyond that they won’t hold their shape. They will not be able to go back to the original form with all of the coils closed. When they are used in high-temperature locations, they often have extra tight coils with no play in them. This is to prevent the heat from being able to make the spring weakened.
The diameter of the coils will decrease when a torsion spring assumes a load. It can act as a mechanical stop too. This is possible if there is something inside of the coil to stop the action from the spring.
There are plenty of types of materials used to create springs. The most commonly used are the various steel alloys. This includes:
Sometimes, it is necessary to rely on other materials to create springs though. It all depends on the desired outcome. What does the spring need to do and how much of a load does it need to handle? There are exotic metals used to create springs to meet a unique demand. They include:
Music wire is a high carbon type of steel. It is often used when a high amount of strength is needed. It is reasonably priced and the quality is excellent. Strings for pianos and guitars are often made from music wire. Many small springs are created from it too. It can’t be plated, but it will contract when heated.
Commonly referred to as OT, oil tempered wire is made from quality steel. It is inexpensive and often relied upon when the outcome doesn’t have to be uniform or offer much strength. It can be plated and it won’t change when it is heated. OT may be rectangle or square shape to help create the right outcome for a given use.
If you need something higher quality than OT, chrome silicon or chrome vanadium could be the solution. They are stronger and offer a higher quality spring. They can be used in high-temperature settings. Of the common uses for such materials is to create valve springs in vehicles. They can be plated and they don’t change when heated.
This is an excellent material for springs because it doesn’t rust. They are often used in locations where there is steam or water. There are two types of stainless steel used to create springs. The 17-7 isn’t going to change when heated but the 302 will have some expansion.
Several of the materials for springs are a good concept, but keep in mind they can’t be plated. This includes:
Such alloys are often used to create springs for high-temperature locations. They may be used where there are challenges due to magnetic fields. They won’t corrode so they are a good choice for humid environments. While they do cost more than other materials, they are going to hold up under harsh conditions. They aren’t going to change due to heat.
Due to the lightweight of titanium, it is frequently used in aircraft. It is very strong and durable but it is expensive. There are also special precautions to take when working with it. For example, the wire can become explosive if there is too much stress placed on it. Titanium can’t be plated and it won’t change due to heat.
When a strong material is needed to create the spring, the amount of load it can hold has to be evaluated. This is the order of strength with the strongest at the top of the list:
Based in Birmingham with a small but highly skilled team, we work to ensure the machines we supply are of top quality, without charging over the odds. Once a machine is sold, we continue to provide manufacturers with expert engineering support and after-sales care.
If you have any queries, please contact us on 0121 772 9796 or using the contact button at the top of any page of this website.
Transworld Engineering Ltd. supplies manufacturing solutions through the sale of high quality machinery and engineering support for spring makers and end users in the UK and European market.
To assist our clients, we are providing a database of information related to springs and spring manufacturing solutions. This article represents part one of this database.
Our first part looks at the different types of spring. Each has its set of applications and performs a different basic function. There are fundamental differences between Spring types, how they are made, the materials they may be manufactured from and their application.
“A compression spring resists a load pushed against or onto it”
Compression springs are perhaps the type of spring you are most likely to see in everyday life. They are found in household objects, engines, manufacturing control and have many domestic and commercial uses.
Compression springs provide some flexibility of movement white the force they provide attempts to return the object or objects the spring is attached to back to its original position.
Compressions springs are used in most forms of automation, cars, trains, aeroplanes. They provide such mundane functionality as door-stops. They can provide basic shock absorption functionality. Providing a load with just enough freedom of movement to prevent fixed stress under vibration, while always looking to return the load to its ideal position.
Hole and Rod. Typically, a compression spring is anchored with a rod which runs through its centre, inside the diameter. This rod prevents the spring from distorting, bulging, or fouling under load.
The free length of a spring refers to the length of the spring material unwound
Compression springs can be manufactured in different shapes. Conical, convex, concave and pipe.
“An extension spring is used to bring things together or place 2 objects attached to the spring under a fixed diametrically opposing load”
Extension springs are most commonly used in situations where some degree of movement should be allowed between 2 objects or one object and its anchor point where the force of the spring encourages the objects to return to their original proximity
For example. In a traditional “up and over” garage door, closing the door extends the spring. Someone closing the door will feel the tension despite having gravity on their side. The door wants to return to its open position. Only when vertical does the mechanism lock, leaving the spring extended and the locking mechanism preventing the door from opening.
It is the initial tension that determines how tightly together the spring is coiled. This initial tension can be manipulated to achieve the load requirements of a particular application. Designs normally have hooks, eyes, or other interface geometry at the ends which attach to the opposing components. They are frequently used to provide a return force to components that extend in an actuated position.
The reverse is true when opening the door. Once started, with the momentum of the first lift, the door easily returns to its up and over position.
“Torsion springs provide a rotary (tangential) force are most typically anchored at both ends and providing radial resistance (torque) to movement.”
These anchors, sometimes known as legs provide radial resistance. Unlike the lateral forces that other spring types provide or resist, torsion springs provide or resist bending stress.
A good example in everyday use that might visualise this is the common office clip board. The clip at the side or top of the board uses a torsion spring, one leg attached to the board itself, the other to the clip. When the clip is lifted it provides pressure which ensures that, once paper is placed between it and the board the pressure ensure the paper remains fixed.
Torsion springs provide an angular torque around their circumference. This force is measured ion kilograms per degree around this circumference.
Torsion springs have a maximum deflection. This is the amount of force needed to overstress the spring. The point at which it will fail in terms of providing too much movement or material stress within the spring itself will occur which usually permanently damages the spring
Maximum Load is the amount of force that can be placed on a spring before maximum deflection is reached
There are three core principles in spring design.
There are some caveats to these rules.
Firstly, they apply to springs made from the same material. Depending on the spring type there are materials suitable for different applications that provide different properties. The rules above apply to springs made with the same material.
The same is true for the age and lifetimes uses of any spring. Due to the stresses of use, the material in any spring will degrade in relation to its ability to perform over time. Different materials provide different projected lifetimes depending on their use case.
The endurance limit is defined for ferrous (steel and iron) material as the stress level below which the material can be cycled infinitely without failure. (Shigley et al., 2003)
http://mech.sharif.edu/~mechengdesign/Shigley's%20Mechanical%20Engineering%20Design_TextBook.pdf
Extended lifetimes can be expected if the spring is made with the correct material for its application. For example, a stainless-steel spring can provide both corrosion resistance and an expected lifespan that can be longer than the application or device it is used in.
However, the correct material for any spring in any given application can vary. There is usually a best material for the job.
Based in Birmingham with a small but highly skilled team, we work to ensure the machines we supply are of top quality, without charging over the odds. Once a machine is sold, we continue to provide manufacturers with expert engineering support and after-sales care.
If you have any queries, please contact us on 0121 772 9796 or using the contact button at the top of any page of this website.
