Neodymium (rare earth) or NdFeB adhesive backed disc magnets are round coin-shaped magnets of varying diameter and thickness which have an adhesive backed layer on one pole. The adhesive layer is a 3M adhesive with a protective backing strip - simply remove the protective backing strip and press the adhesive backed Neodymium disc magnets onto the item you want to adhere to.
The adhesive layer is placed on one magnetic pole. So a North described adhesive backed NdFeB disc magnet has the magnetic North pole visible and the magnetic South pole has the adhesive backing. A South described adhesive backed Neodymium disc magnet has the magnetic South pole visible and the magnetic North pole has the adhesive backing.
Using the Adhesive Backed Neodymium Magnets to Attract a Ferromagnetic Surface
When using the magnets to attract a ferromagnetic surface (such as mild steel), either type of NdFeB adhesive backed disc magnet can be used (you could use all Souths or all Norths or even a combination - it does not matter). Sometimes, if the magnets are spaced apart near enough to each other, you could consider using alternate Norths and Souths as this may possibly give a small boost to performance (because the magnets interact is a positive way, attracting and pulling the fields around each other).
A North version of a Neodymium adhesive backed disc magnet will have the same performance as a same-sized South version of the NdFeB adhesive backed disc magnet.
The Neodymium magnets will attract or repel each other depending on how the magnets are placed relative to each other. For attraction you need a North pole face on one magnet directed to a South pole face on the other magnet (following the magnetic rule of unlike poles attract). If a North faces another North or a South faces another South you have like poles which means repulsion. In some applications the magnet is hidden (e.g. the magnet is adhered to card which is then folded over to hide the magnet away which results in the magnet pole being turned over as well). So knowing how you want the magnets placing in the final assembly could affect the polarity you need for your magnets.
Such NdFeB adhesive backed disc magnets are very popular with the printing, packaging and arts and crafts industries as well as for use in the office and at home.
The NdFeB adhesive backed disc magnets are axially magnetised (the thickness of the disc is the distance between the North and South circular pole faces - the magnet is magnetised along the central axis).
Adhesive Backed Nickel Plated Neodymium Disc Magnets
The Neodymium adhesive backed disc magnets are usually nickel plated as standard. Other coatings may be possible e.g. black epoxy. Other grades may also be possible. We can supply custom magnets. But please be aware that the adhesive layer has a performance limit - if the NdFeB adhesive backed disc magnet gets too big then the magnetic pull may become more powerful than the adhesive pull. As such we do not offer such powerful magnets unless specifically asked to produce such a custom shape (so we can be assured that the customer understands the performance limits of the adhesive layer) - this is why our magnets are not offered online in such large sizes.
Please also be aware that the adhesive layer will work well with card, steel and paper, etc but may not perform so well with some of the plastics. If the plastic has a very smooth or oily texture to it, the adhesive may struggle to hold on to the plastic longer term (roughening the texture to provide more binding surface area may assist but is not guaranteed). We suggest testing on your plastic before using mass production.
If you are in any doubt about the choice of magnet, its size or need technical assistance, please contact us. And if you need a quotation for higher quantities or a custom magnet shape, please contact us.
If you need magnets for higher temperature applications see our range of Alnico magnets.