Different materials provide different properties in spring making. Here we take a look at the most common materials used:
Although the intended use is always the deciding factor behind selecting the type of material, low alloy steel is usually better ferrous material than carbon steel in several ways. Manufacturers create low alloy steel by adding a set ratio of alloy elements like Molybdenum, Chromium, or Nickel.
Low alloy steel material provides several specific benefits over mild steel, making it appropriate for particular categories of springs. Low alloy steels feature extremely high-temperature properties leading to hot compressive strength. It implies that such springs get a crucial property of lasting much longer under axial stress. Research documentation proves that the addition of any of the three alloy elements can improve creep strength to achieve this sought after property of axial stress: Nickel, Moly, or Chromium.
The cold-forming process is well known to provide better temperature tolerance, stress tolerance, and tensile strength, in addition to the usual benefit of improved surface finish. Cold drawing refers to the work-hardening effect. It alters the basic crystalline structure of steel, leading to a change in its mechanical properties.
Skilled spring manufacturers use several methods to manufacture different spring and wire forms. They can achieve the required capabilities and qualities for various applications.
Oil tempered spring wires are vital for everyday life as we use them widely for the automobile industry. Several small classifications define the wire properties in this category, including fatigue stress. We often use these wires in products like cars where suspension is critical for the functional ability of the device.
Hardened steel is essential for creating material that can provide more excellent fatigue resistance and strength. Bainitic hardening involves heat treatment of steel to get the desired properties. People prefer bainitic tempering to martensitic steels because this process hardly needs any additional heat treatment.
Manufacturers create stainless steel by increasing the composition of chromium in the steel to a minimum of 10%, although practically, it is often close to 17% of steel. Moreover, it also includes 7% nickel, a little magnesium, and some carbon too. All these elements work together to create the most incredible quality of stainless spring steel which lies in its extraordinary yield strength.
Apart from making springs, people also use stainless spring steel in diverse applications like antennae, lock picks, and washers. There are many applications for stainless spring steel, but this material features a very important property of protecting against corrosion.
It offers protection against oxidisation and some organic acids due to a high chromium concentration in the steel. On the other hand, the Nickel element in the steel gives protection against atmosphere elements and acids like phosphoric acid.
Stainless spring steel is also appropriate for application requiring to endure high temperatures. You can hot work this type of steel below 1,700 degrees F. You may have to work at a temperature of around 2,100 degrees F to forge the stainless spring steel successfully. That is why most stainless steel forming work involves manufacturing via the cold working process. However, it may create unwanted magnetism in the material, which you will have to treat after the casting work is complete.
Mostly steel and its different alloys remain in high demand due to their versatility and affordable costing. However, some people also work with titanium or copper alloys. You can create Titanium alloys by using elements like molybdenum and Aluminium.
It is important to note here that Titanium alloys are much more expensive than usual steel alloys. It implies that you should prefer titanium alloys for working only in specific circumstances where you can justify higher costing. In most such cases, the application requires a high degree of precision in the final product. Prominent examples of such applications may include space travel or military aircraft work where accuracy is crucial, and you can justify higher costing.
People use both copper and titanium alloys in creating torsion springs. Such springs find their use in hinges and doors for regular service or even sophisticated medical equipment. Similarly, such material is also appropriate for use in retractable seats.
This article refers to the mechanics and operation of a small-scale spring rolling machine. The project scope includes the application of this spring-making machine in the small-scale industry. It can produce open and closed helical springs having different spring and spring coil diameters. One can make use of this machine to manufacture springs on a small scale without much expenditure.
In the first instance, the procedure for making springs is the same whether fully automated, or partly manual in process. The advantage of seeing a manual machine is that it is possible to see much more of the process, and therefore to understand both he processes, and the various stages material will go through as it is formed into a spring.
Therefore, the aim would be to learn about several types of springs used in different automotive parts and similar mechanisms. It also throws light on the crucial role played by these springs in different kinds of instruments.
The example suggests that you have prepared the spring-making machine with a very simple arrangement. You can operate this machine manually to produce closed coil helical springs of different lengths and diameters.
This project explains how a spring rolling machine works. Please note that the term rolling refers to a process whereby the operator bends a metal wire in a curved form to create different springs.
Here is a simplified explanation of the machine layout and how the machine works.
When you rotate the handwheel, it makes the shaft run—an MS plate layout couples the primary shaft with the bearing. The handwheel rotation makes the main shaft rotate. Before turning the handwheel, you have to lock the wire with the locking nut of the spring mandrel.
A guide affixed to the machine-frame stand of the spring-making machine applies the load to supply the said wire. The guide can rotate freely as per the shaft speed.
One end of the primary shaft is joined to that chuck. Similarly, the other end of the same is connected to the handwheel. A mandrel with several diameters (or a spindle shaft) is joined to that chuck, and then it starts to rotate.
When you turn the handwheel, it turns the rolling shaft. The same part makes the spring roll. The operator can decide the changes in the spring length based on the spring rotation. Once the operator has completed the aimed spring length, he can stop the handwheel rotation.
The operator keeps on rolling the spring wire until the desired length is achieved. It marks the end of the production of the final product of spring. You can repeat the entire procedure for mass production.
Those of you familiar with Hooke’s law will be aware that the force a material exerts is proportional to the energy used to deform it.
In other words. The more you try and bend or deform a material, the harder it is to deform it further.
Hooke's law is a law of physics that states that the force (F) needed to extend or compress a spring by some distance (x) scales linearly with respect to that distance—that is, Fs = kx, where k is a constant factor characteristic of the spring (i.e., its stiffness), and x is small compared to the total possible deformation of the spring. The law is named after 17th-century British physicist Robert Hooke. He first stated the law in 1676 as a Latin anagram.
He published the solution of his anagram in 1678 as: ut tensio, sic vis ("as the extension, so the force" or "the extension is proportional to the force"). Hooke states in the 1678 work that he was aware of the law since 1660.
Constant force springs are best used as a counterbalance. In everyday application these springs are used most commonly to supply a retracting force for items such as self-closing doors, seatbelts and interior blinds.
Variable diameter springs do not have a constant diameter when measured across the length of the spring.
The variable diameter means that the spring does not follow Hooke’s law F=- kX
Where F = Force, k is the proportional constant and x is the change in length from the equilibrium.
The minus is there as the force we are talking about is the counter to the force of exertion. In other words it is a responsive force. “-k” the force within the spring, is countering “k” the force exerted on the spring.
The constant force spring is a resilient, rolled up spring that provides a constant and lasting force to the connection. A variable diameter spring, depending on how it is set up can provide either decreasing or increasing resistance to force as the spring is extended or compressed.
The helical nature of the spring means that each full diameter of a variable diameter spring fits inside the preceding diameter.
Within a battery compartment. There may be a pressure leaf or, more commonly to provide stronger force, a variable diameter spring. When placing a AA battery the positive end will often be pressed against a leaf, and the negative (flat) end will then be pushed into place against pressure from
High end mattresses may be sprung. Often having pocketed springs that compress to provide support for the sleeper. They also provide lateral flex so as not to resist movement of the sleeper and give even support regardless of the angle of compression.
Vehicle suspension systems. The ability for the spring to compress to a low height is an important consideration for some applications where space is at a premium.
The spring’s characteristic is determined by two factors. On one hand, by the minimum distance between two adjacent coils, for the unloaded spring, distance which decreases with increasing wire diameter.
On the other hand, by the coils’ deflection, which decreases with increasing wire diameter. Consequently, the actual distance between the adjacent coils represents the difference between the two sizes. As a result, the adjacent coils will successively touch each other, depending on the actual distance between them, and the spring stiffness will usually be increasing.
See the definition for active coils here.
The point at which a spring will become permanently deformed due to the stress. The elastic limit is a function of the spring’s material, the number of coils, the length of the spring and the tightness of the wind.
A zinc coating of steel to prevent oxidisation. The spring material is placed in a solution containing zinc at a high temperature. Typically, at 450 degrees C
A spring designed to provide resistance against extension.
In the case of spring manufacture this is a term used to describe the gradual wearing of spring material over long use periods. Micro fractures in the spring material occur under load and increase in severity over time. The fatigue process can be accelerated by processes such as oxidisation and be mitigated by strengthening the original spring material and by aging and hardening the springs material to provide stronger molecular bonds.
The length of a spring when assembled into the position, within a mechanism, from which it is required to function. This will often vary from the resting or manufactured length as allowances are made for springs to extend or compress under load.
A torsion spring is a spring where the spring ends are open and extend at a tangent from the main body. Typically, at 90 degrees from each other. The springs body provides resistance to these ends preventing them from being easily compressed (the angle between them decreased under pressure) or extended (the angle between the legs increases under load). The free angle is the angle between the legs of a torsion spring when the spring is not loaded.
The length of a spring when it is not loaded. In the case of extension springs this includes the anchor points.
Gauge has two distinct meaning. Gauge of material. The thickness of the material used in constructing a spring. It can also refer to the device used to measure aspects of the spring. You may use a gauge such as a digital caliper to measure the gauge of spring material.
The removal of metal from the end faces of a spring by the use of abrasive wheels to obtain a flat surface, which is square with the spring axis.
The end of a spring is ground to provide a flat plane. Handing The direction in which the helix of a spring is formed.
A term for coils under tension. Those coils of a spring that are actively under tension, stress, or load at any point of their use.
This can be roughly calculated by dividing the length of the body by the diameter of the spring then subtracting one.
The heating and setting process of the material of a spring so that the molecular structure is as evenly distributed as possible reducing the chances for weak spots.
A spring is supplied slightly over sized when used in a compression situation allowing for the settling of the spring material under stress.
Distortion of the spring, typically along its length. This can happen when a spring under load exceeds its tolerances.
An incomplete circle of material designed to resist extension used to clip or clamp an object. Pressure applied to the flanges opens the clip and the resistance in the material closes and fixes it. A commonplace example to help illustrate this might be the clips around a downpipe from a roof gutter.
A spring where the helical pattern of the main body of the spring is compressed or reduced giving a much tighter radius on the final coil. Closed end springs may also be ground in this final circuit to provide a flatter surface for contact to provide more stability.
Similar to close ends, in this case the final turn is reduced tightening, flattening and sometimes grinding so that at the end of the last diameter the spring is at the same height as the start of the final diameter.
A spring material wound in helix around a central axis (actual or geometric). Each complete diameter is called a coil. Often forming a cylinder or, if tapered with decreasing or increasing diameters a cone.
Using coils as described above, constructed to resist compression. The load they can effectively withstand is a function of the number of coils, the material the spring is constructed from and the diameter of each coil.
A spring where the diameter around the central axis increases or decreases along its length forming a cone shape.
Coils, often at the beginning or end of a spring that do not contribute to its rate of extension or expansion. Most often used to provide stability and increase the length between a springs anchor points without introducing greater stress to extended (active) coils.
(Thanks to softschools.com for this succinct definition)
According to Newton's Third Law of Motion, as a spring is pulled, it pulls back with a restoring force. This force follows Hooke's Law, which relates the force of the spring to the spring constant, and the displacement of the spring from its original position.
force of the spring = -(spring constant k)(displacement)
F = -kx
F = restoring force of the spring (directed toward equilibrium)
k = spring constant (units N/m)
x = displacement of the spring from its equilibrium position
Part 2 of 2
You have to continue counting until you achieve the active target coils in the completed compression spring. Then let it wind a couple of more coils. Keep counting and unfasten the lead screw. The wire lays on itself and starts forming closed coils.
If you have additional wire left, cut it. Afterwards, you have to put the compression spring in the oven to reduce any stress. In this trial process, you have to leave it inside for about thirty minutes. Remember that this process of relieving stress will make the music wire springs contract a little. In the case of stainless steel springs, it expands a little.
After completing the process, allow the compression spring to cool down at room temperature, i.e. by air-cooling. You can measure the spring to find out how near you are to the target. You should check the diameter initially. If the diameter is not correct, you need not bother to do any more measurements. You will require a different arbour which changes all the remaining dimensions of the compression spring.
However, if the diameter is perfect, count the active coils of the compression spring. If would be nice if you ended up quite close to your target. It is fair to be one-fourth of it off on either way for a smaller figure of springs. If it has more than 25% variation, you have to calculate how much additional or lesser you require and try achieving the target coil count next time.
You may also coil compression spring on your lathe without using the lead screw. But here the problem is that you may not make the same springs. Let us learn how to do it without a lead screw.
(Part 1 of 2)
This article will explain the process of manufacturing compression springs. The best way to learn the manufacturing process is to try making them by hand. This way, you will be able to appreciate what the machine does. You can find errors in the mechanical process, make the required changes to make it better, and apply your experience from your manual spring-making trials. Since its manufacturing is a little complicated, we are looking in a little more depth than you might expect. After all if you can do this manually, you know "what good looks like" when a machine does it. So, here we discuss in greater detail to catch this process's nuances and subtleties.
Before we proceed further, we need to gather some information about how the equipment works while manufacturing compression springs. First of all, let us have a word about the pitch of a compression spring. The pitch is the distance from one open coil to another open coil of a compression spring. It is essential to understand that you need to control the wire guide's speed travelling from the left side to right side when the arbour turns around. By controlling this speed, you can quickly make a spring with a required pitch.
It is easier to do so using a lathe. You can manage the speed by engaging its lead screw. It will automatically maintain the required pitch. However, you will probably be using a hand winder or a drill to control the manual process speed. It is quite challenging to manage it manually. We are not saying that it is impossible to manage it by hand, but comparatively, it is only a little more complicated.
To get around this problem, the spring shops buy a hand winder machine. Such winding equipment can manufacture lightweight springs easily. The hand-winding machine manufacturers have designed the machine in such a way that you can manufacture any quantity of compression springs after setting up that machine. The best part is that all the springs manufactured so will be precisely the same.
However, in the case of a lathe machine, although you may believe that you are doing the similar process every time, you are highly likely to generate different springs, especially in the case of a light wire. That is the differentiation between manufacturing the spring by visual observation and using professional equipment.
To begin the manufacturing process, you need to estimate the amount of wire required to make one compression spring. You can use the following method:
1. Multiply the wire's outside diameter (OD) with 3.3 (An approximation of Pi - plus a little extra)
2. Decide the number of coils needed in the resulting spring
3. Multiply the figures for the above two results to give you the required wire length
4. Increase the result of by a little buffer. You can take it as 6 feet for a heavy wire, 3 feet for a medium wire, and 6 inches for a light wire. Here though you are best using your judgement and taking your surrounding's and the tolerances of your equipment into account.
5. You should note down this resulting figure. If it is much higher than you expect, take a second look at your calculations. They are probably correct. The amount of wire in a spring is often a surprise to someone who has not made seen one being made, However, if you are over by a substantial amount remember to recut. It will save you time in the long run.
Before beginning, you need to ensure two things: firstly, engage the back gear, and secondly, put the lead screw in a correct position. Keep in mind that the lathe speed depends upon the wire dia. The higher the diameter, the slower is the lathe speed. Now, let us learn to set the speed of your lead screw.
You have to ensure the lead screw to go left to right on engaging it.
The lead screw speed should be set such that you get appropriate coil spacing along the arbour. You can guess it or measure it mathematically to decide the pitch.
The easiest way to estimate the coil distance is as follows:
* · Subtract 5.5 times Wire dia from the wire length
* · Divide this figure by the figure of active coils
Switch on the lathe to involve the lead screw. Tightly hold chalk on the tool post to bring the post near the arbour so that the chalk touches it. Allow the chalk to mark the arbour for at least two turns. Now halt the lathe machine.
You can compare your target pitch with the measurement of the distance of chalk marks. It would be best if you regulated the speed until both measurements are the same.
After the lead screw speed setting is done, you can proceed with making your first spring.
You can start coiling. Let the chuck move slowly to one complete coil. Make a minimum of two complete coils, and they should touch each other. You can do so by keeping the wire guide slightly on the left where your wire is put on the arbour.
After making two full coils on the arbour, you should ensure the following two things simultaneously.
As part of our continuing series to simplify some of the concepts around spring manufacture we look at the manufacture of the extension springs. It is helpful to consider the process from the perspective of creating the product manually so as to better visualise the process and concepts involved. It goes without saying that at Transworld Engineering we have the tools and machines to automate this process for you. If you would like to learn more, then why not book a visit to our showroom.
The following section will explain how to manufacture extension springs
When creating individual springs for testing There is little need to calculate the precise length of wire required per spring for manufacturing short extension springs with wire up to approximately 0.250" or light wire. However, it would help if you had a sufficient buffer of extra length. To estimate the wire length, you can take the actual measurement of the spring's length. Divide the wire length by wire size to calculate the estimated number of coils in the spring. Multiply that figure by 3.3 (an exaggerated Value of Pi). It will result in a wire a little longer than your requirement, which should not be an issue as you can use the first few springs in the loop making setup.
You are now ready to manufacture the extension spring.
Cut a piece of wire in the correct length. In the case of light wire, you can undo the wire and put it in front of the winding machine or lathe. To avoid tangling of wire, start by taking the wire end inside the coil as your starting end. You may coil multiple springs simultaneously by cutting off a longer wire length if you want to coil short springs.
You can now fire up the oven while ensuring that other people in the area remain out of danger while completing the rest of the process.
You need to put the wire into this setup and bring the wire guide to the left side near the pickup pin.
Begin the coiling process. Move the chuck carefully while ensuring that the wire rests on the pickup pin, which in turn should be seated on the wire guide. You can now allow a few coils to lay down on the finishing plate.
Once you lay down a couple of first coils on the finishing plate, you can proceed to the next step. At this point, you need to ensure the functioning of the following two processes simultaneously.
1. Move the wire guide slightly to the left side. You should ensure a gap between the two initial coils while laying down the wire over the finishing plate. At the same time, you should not let the wire run over itself when you turn the finishing plate.
The idea of keeping a gap controls the "initial tension." Such initial tension is the vital force in the wire, which applies some pressure on the spring to break the coils apart. For example, there is enough initial tension in Garage door springs. However, there is hardly any initial tension in slinky toys, which are essentially extension springs without any loops.
2. You have to discontinue winding if you notice any of the following two events
a. You have got to the point beyond which you can't approach your lathe machine's "off" switch.
b. You don't have any more wire left.
Now, the wire guide has comes closer to the endpoint of the finishing plate.
Back off the chuck to allow the spring to remain loose on the finishing plate. In case you are using a light wire, you may hold the spring body close to the chuck and pull the dogleg out. It will loosen your grip to allow the coils to unwind slowly. Finally, move the wire guide by sliding it and spring off the finishing plate.
Now you can put the spring into the oven to relieve the stress. Please note that springs manufactured from stainless steel will expand slightly with the heat. On the other hand, springs made from music wire will contract a little.
After you have completed this process, you should allow the springs to air cool. Afterward, you can check the diameter for accuracy. If you have followed it properly and ensured the setup as explained, you should get the exact diameter you had planned.
Now observe the coils of the extension springs. All those coils must lay flat against each other up to the end of the spring body. If you notice any gaps in the spring body, it implies that you had allowed the wire guide to slide to the right side at the time of coiling.
If we consider the manufacturing of extension springs as a manual process, which isn't the usual case here at Transworld Engineering of course, it is easier to highlight the differences between the manufactured level of tension in an extension spring, and the typical and reasonable operating tension.
In the manufacture of an extension spring, there are things that we need to consider. One of these is the initial tension of the extension springs and how it relates to the working tension of the springs in their daily uses. The probability of there being a difference is high. The loops at the end of your spring’s end may or may not cross or line up with each other. Where your spring is long enough, you can opt to twists these loops to make them cross or align with each other. They will remain held in that position due to the initial tension.
It is essential to assume the loop position.
Below, we are going to discuss the process of making a basic type of loop that has no frills and will work with most springs. You can make other types of spring loops that are stronger, more efficient, and prettier. However, there are specific tools that you must have for you to make these types of loops.
1. Cut and get rid of the spring’s end. It is crucial as you will leave the coils that are in contact with each other all the way around.
2. Mount and firmly your spring in a vice between the two looping plates.
3. Using your looping rod, reach into the spring’s centre and hook your rod’s tip under the first coil.
4. Push the rod downwards to apply pressure that will bend the rod upwards. Let go of the rod when the coil top is directly above the spring’s centre.
5. Reach under the already bent coil using a looping rod and using the tip’s rod, snag up the end of the wire.
6. To align the coil’s end with the spring’s body, apply pressure to bend it.
After performing this procedure, you will have made one end of the spring. The next step in creating a simple loop is figuring out the length of wire that you need to get rid of on the other end to achieve the desired length. If you wish to make it a little short, extend your hooks. All you need to do is straighten out the wire once you take it off the body of your spring.
Where you aim to make just one short spring from your coil, count the coils you have and depending on the number you need, add or remove to remain with the number of coils you need. If you have wound a long coil when you are making a short spring, repeat the same thing. Using your wire cutters (or a cut-off-wheel where you are working with a heavier wire), from the main body, detach the first spring.
Cut off some parts of the whole coil for you to achieve the right length. However, keep in mind that you are only needed to add to each end of spring “just shy of a full coil” for you to achieve a high-quality product.
Alternatively, where you have a long spring (or where you do not wish to waste your time counting the number of coils), all you need to do is measure the coil’s body and make an addition of about 1 coil.
Once you trim the body of the coil to size, proceed to make the second loop. The procedure for making the second loop is similar to that of making the first loop. To ascertain if you have come up with the desired length of, double-check the spring inside one hook to the inside of the other. Checking in this manner allows you to get the best and accurate results.
Where the length of the spring you have made is very short, there are several options for you to correct it. You can choose to either make the next spring with a fancier loop type or with more coils.
For most extension springs, loops are the most convenient and ideal. However, there are times that you will need to use hooks for efficiency. For instance, you need to use a hook when you want to slip your spring onto a pin.
There are times where hooks that swivel are ideal for making extension springs, but if you do not have kick press tooling, it is a challenging task. For you to be on the safer side, ensure you purchase a commercially made one.