The Coil Winding Process

How the Coil Winding Process Works

This article describes the coil winding process for standard sensors and miniature medical sensors. The process demands that the wire does not touch itself as it is wound around a core or other shape. First, the wire is isolated, or coated, with insulation and wound around a core or a pin. This arrangement creates electromagnetic induction. 

All copper coils used in the winding process contain wires that are insulated. Benatav uses a polyamide base material as insulation. However, several materials are available that are resistant to temperatures and breakdown voltages. 

Most windings produce shaped coils. 

Differences between Coils

The main difference between coils is their shape and therefore their electrical values. They can be wound into the following forms:

  • round 
  • elliptical 
  • rectangular

The inner and outer dimensions of the coil are crucial. 

The Coil Winding Process for Medical Grade Sensors

The most crucial parameter for winding medical grade coils is the size. For example, to insert a coil into a vein, the coil must be smaller than 0.8 mm, including the coating or insulation for the wire. This requires highly specialized machinery that must be designed and built in-house. 

Coils are made from insulated copper wire wound about a core or a pin. They can also be:

  • coreless and self-bonded, i.e., the coil is bound to itself during the winding process. 
  • wound around a shape, such as a rectangle. Afterwards, the rectangular shape is removed, leaving a rectangular-shaped coil.

Benatav has plans to wind coil using wire that is thinner than 8 microns which will make it the thinnest coil in the world.

How Do You Prepare Micro-Coils?

If it’s a miniature sensor that is made of coils, first and foremost you need to have:

  • know-how regarding winding miniature coils. 
  • special equipment that cannot be found at the standard coil makers. 

You cannot simply go and buy a machine capable of winding micro-coils. It doesn’t exist. You need to engineer such machinery and create it from scratch. At Benatav, we call this in-house engineering. For everything related to miniature coils, whether it’s leads for wire terminals or soldering, you need special machinery that you create in-house.

You use ultra-fine wires to manufacture inductive components and provide connectivity within miniature medical devices. This requires the interplay of several innovative technologies. These technologies are predicated on an array of methods for handling copper and other metal wires at any diameter, down to the finest serially manufactured size of 59 AWG (9 microns or 0.00035 inches). Handling wires which can be 510 times thinner than a human hair is a non-trivial issue, especially if the expected final shape of the wound coil is constrained by a long list of physical and environmental factors and must meet very strict tolerance requirements. 

The machinery used for winding such coils, which controls and monitors the wire’s position and tension at any given time during the winding process, is in most cases custom-built by the coil manufacturer, and requires state-of-the-art micro-motion and control systems. As a result, only a handful of manufacturers in the world have the technical capability to serially manufacture coils that small.

For More Information about the Coil Winding Process 

To create miniature coils requires a manufacturer uniquely qualified to wind ultra-fine wire and produce micro-coils. Benatav Advanced Winding Technologies is ready to help you with any questions or concerns about the process. To contact them, please phone +972-3-934 5951 or write to