How are flexible magnets manufactured?

2nd March 2020


	How are flexible magnets manufactured?


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

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

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

			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.