How are flexible magnets manufactured?

- May 25, 2019-

Flexible magnets are the same as ferrite magnets with the addition of synthetic rubber which makes them flexible. A ferrite magnet is an alloy made of strontium carbonate and iron oxide.


Flexible magnets can be made in two different ways, either by extrusion, or calendering. The two different processes are needed to create the different widths of flexible magnet.


Extrusion, which involves shaping the molten material used to make a magnet with a die, is used for the thin flexible warehouse magnets and flexible magnetic tape.


Calendering, on the other hand, where the molten material is forced between rollers, is used to create the wide flexible magnetic sheets.


Extrusion

Step 1 - Calcination

A powdered mixture of iron oxide, strontium carbonate, and synthetic rubber is heated in an induction furnace to a 1350°C (2462°F) to create a metal oxide. 

Step 2 - Shaping

The molten material is then forced through a hardened die which is the shape of the final magnet. For example, a flexible warehouse magnet will be forced through a die with a C profile.

 

Step 3 - Cooling and magnetising

As the material flows through the die, it cools into shape. Once the magnet has cooled, it is moved over a magnetising plate which magnetises the flexible magnet with a strong electromagnet.


Step 4 - Laminating

The flexible magnet is then laminated with either a vinyl top layer or an adhesive with a HMT hot melt film laminating machine.


Step 5 - Cutting and rolling

The flexible magnet is then cut to the required length and rolled onto a core. A core is the round piece of material in the centre of a roll of flexible magnetic tape.


Calendering

Step 1 - Calcination

A powdered mixture of iron oxide, strontium carbonate, and synthetic rubber is heated in an induction furnace to 1350°C (2462°F) to create a metal oxide.

Step 2 - Rolling

The molten material is then squeezed through two rollers to flatten it into a sheet whilst it is cooling. To achieve a depth between 0.2mm (0.008") to 5mm (0.2"), the sheet is squeezed through the rollers several times.

Step 3 - Magnetising

Next the sheet is moved over a magnetising plate which magnetises the flexible magnetic sheet with a strong electromagnet.


Step 4 - Laminating

The flexible magnetic sheet is then laminated with either a vinyl top layer or an adhesive with a HMT hot melt film laminating machine


Step 5 - Cutting and rolling onto core

The flexible magnetic sheet is then cut to the required length and rolled onto a core. A core is the round piece of material in the centre of a roll of a flexible magnetic sheet.