Magnets & adhesives: not as “poles apart” as you might think.

With more machines, vehicles and tools being made than ever before, it’s no surprise that the electric motor market continues to grow and many manufacturers are still curious as to the best way of installing magnets onto their electric motors.

With so many assembly methods, choosing the right one can be a minefield!

A popular method involves the pressing of magnets into machined slots, or grooves, in the rotor or stator core (press fitting). Then there’s welding magnets to the motor housing, which also provides a strong, secure bond.

Injection moulding is another common method for installation, whereby a magnet is placed into a mould, then a molten material, normally metal or plastic, is shaped around it.

With the various great benefits of all these methods, also come their disadvantages. For example, magnets by nature are brittle, do not tolerate high stress and therefore without the right tolerances, magnets can break, crack or fracture (Press fitting). High temperatures can lead to magnet demagnetisation or an alteration of magnetic properties (welding), as well as exorbitant set up costs that still don’t provide fool-proof solutions (injection moulding). Even mechanical fasteners which tend to be a fairly reliable, low-cost option and compatible with a wide range of motor designs, have the drawback of adding weight creating significant instability to the motor.

So how would adhesives provide a better solution?

Generally speaking, adhesives offer the benefits of evenly distributing joint stress (which reduces the chance of local stress fractures) with a tendency to dampen vibration, are anti-corrosive (in some cases) and ensure ease of assembly, not to mention being cost-effective.

There are a variety of adhesive chemistries that provide many solutions for most magnet bonding applications and while yes, they each have their respective downsides too (ie less than optimal temperature resistance, the long curing time of some adhesives, potential for outgassing), if the time is taken to select the best adhesive for a particular motor magnet operation, the rewards will far outweigh any potential drawbacks.

Given the extensive range of adhesives on offer, a good place to start for any motor magnet bonding research, might be Permabond TA459 with Initiator 41 - click here for more information or contact Permabond here for friendly, helpful technical advice at your fingertips. / 0800 975 9800 /

George Moore – Writer

George is one of Permabond’s newer writers, having joined the company last year. He has a passion for language and words as well as a keen interest in SEO.Having worked as an English teacher for many years, he has a good eye for grammar and style, focusing on natural-sounding writing that convinces.He also speaks German and Russian and has self-published a novel on Amazon.