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How are flexible magnets manufactured?

Shop for Flexible Magnets
Flexible magnetic sheet being stretched 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. For more information see page, What are magnets made of?
Flexible magnetic tape and a flexible warehouse magnet 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.
Flexible magnetic labels/sheet Calendering, on the other hand, where the molten material is forced between rollers, is used to create the wide flexible magnetic sheets.

Extrusion

Adding iron oxide, strontium carbonate and synthetic rubber to an induction furnace

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.

Wonkee Donkee says "Calcination is the term used to describe heating metals whilst oxygen is still present"
Extruding a flexible warehouse magnet through a die

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.

For more information on a ‘C’ profile magnet, see page What are the parts of a flexible warehouse magnet?

Magnetising forces

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.

Laminated flexible magnetic tape

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.

For more information on adhesives and laminates, see page What are the parts of a flexible magnetic tape?

Rolling flexible magnetic tape onto a core

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

Adding iron oxide, strontium carbonate and synthetic rubber to an induction furnace

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.

Calendering a flexible magnetic sheet

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.

Magnetising forces

Step 3 – Magnetising

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

Laminated magnetic sheets

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

For more information on the types of adhesives and laminates, see the page: What are the parts of a flexible magnetic sheet?

Rolling flexible magnetic sheet onto a core

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.