Manufacture of Compression Springs Part One

19th January 2021

Making a Compression Spring by Hand

(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.

Calculating Wire Length

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.

 

Making The First Trial Spring

After the lead screw speed setting is done, you can proceed with making your first spring.

 

  • Cut the wire length you calculated above. Ensure that nobody else is around to minimise danger during the remaining process. Simultaneously, arrange to heat your oven as well.
  • Feed the wire and bring the wire guide on the left side close to your pickup pin to ensure that your wire engages both of them.
  • Please ensure that you read and understand this step fully well before going further.

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.

 

  • Occupy the lead screw. Provided you wind wires above 0.187 inches, you should not grasp the lead screw controls from above the wire but instead below the wire. It is so because the wire will not cause any injury if it flicks back if your wire guide accidentally breaks.
  • Count you coils from here onwards. Count it once every time the active coil leaves the point which separates it from the end coils passing the chuck top.