How do I get a tidy and even layered coil?

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How do I get a tidy and even layered coil?

Answer:

Helical winding

Using the Automatic Winding tab of the software will create the typical helix/helical winding pattern, which can be good for a few layers but can be hard to maintain when your layers get too much.

To get a more tidy coil when doing a Helix coil and get a even layered coil there are a few things to consider.

  • Tension needs to be correct along with speed. If the tension is not enough then the wire could jump and have kinks in it. If it is too much then it can cause the sides of the bobbin to flare out as the layers build up.
  • Where the wire enters the bobbin this must not cause any kind of bump or kink as your first couple of layers need to be wound spot on for the others to follow in a uniformed way.
    One design method is a bottom wire guide hole, usually at a slant so you do not get a bulge at the beginning of the first winding.
    Also the sides of the bobbin need to be rigid enough to stop them moving outwards as the layers build up and using custom made holders either side of the bobbin can help stop this on weaker bobbins.
  • The wire must fit the width of the bobbin based on the amount of turns for each layer, if not this will either cause build up on one side or wire on below layer may slip and allow a winding to drop between it.
    Allow for 10-15% for the coating on the wire when setting the diameter, better to measure with some accurate callipers.
  • Make sure that you allow for the resolution of the machine. We have increased the resolution of the new 200mm Coil Winder MK5 to 0.0003125mm, so for example if you had 0.1mm wire then 0.1/0.0003125=320 which means it will fit within the machines resolution, but if your wire was 0.133mm the 0.133/0.0003125=425.6 which is not a whole number, but the software will calculate it for you and modify the wire size to 0.133125mm. I know this is only a small increase but worth noting.

This is why the more expensive commercial coil winding machines you see around are setup to do one coil in a production environment. The recipe for the particular coil gets set up by the manufacturer, along with the wire, bobbin spec and correct tension. Then the machine is used in production to just produce that one coil, over and over again.

Our machines are designed for R&D or small batch runs where you would need to experiment with the considerations listed above to get the winding pattern you require. But in our software we allow full control of each Axis down to degree level using scripts and our machines can be used to wind some very weird and wonderful coil designs.

 

Orthocyclic winding

The Orthocyclic winding pattern can be considered as parallel winding. The turn is wound in its location and immediately wire is shifted to the next location for the next turn within the fraction portion of the turn. This pattern goes on continuously for every turn wound and every layer. So the turns are straight or parallel to each other except the fraction of each turn when the wire is shifted to next turn position. On the next layer the turn is between the gap of the two turns of the bottom layer and this goes on for every layer. So the actual area required for two layer winding is less by the air gap between two turns. This pattern of winding will allow maximum copper feeling within given area of bobbin.

Below image is orthocyclic winding where the bobbin edge is stepped in to help with the starting shape.

 

Orthocyclic winding can produce perfect layers and and a very neat coil can be achieved.
The Scripting engine will allow you to build up the orthocyclic  pattern, but will take time to get your script created but will give a perfectly layered coil.

As you can see in the picture below each winding goes around to approx 330 degrees of the bobbin and then the other 30 degree of the turn brings it up to start the next winding (Cross Over).

Next time this winding comes around it would start at say 329 degrees and do the same thing. But as each winding is laid down the start point of the cross over would decrease. The value that it decreases will depend on the amount of turns per layer and also will change as the coil diameter gets larger.
A good reference to the maths is in the following PDF
https://www.pearl-hifi.com/06_Lit_Archive/02_PEARL_Arch/Vol_16/Sec_53/Philips_Tech_Review/PTechReview-23-1961_62-365.pdf

You could create an excel spreadsheet with formulas to do the calculations and then export the positions in CSV format for the Absolute Scripting Engine.

 

Please check the link below for more information.
https://en.wikipedia.org/wiki/Coil_winding_technology

 


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