Magnet-Bonding System from 3M Provides Alternative to Liquid Adhesives


An innovative tape-like magnet bonding adhesive system developed by 3M has proven to be an attractive alternative to liquid adhesives, say company officials. The product, AU-205, was designed to provide electric motor design and manufacturing engineers with an advanced tool for bonding permanent magnets to rotors and stators in high-efficiency permanent magnet electric motors.


Its construction combines a modified structural epoxy adhesive with a thickness control system, configured in a low-tack double-sided tape product. As a result, it provides strong bond strength and chemical resistance in an easy-to-convert tape form.

For manufacturers, this can simplify permanent magnet positioning. The adhesive does not require mixing or liquid metering, or complex production equipment. In addition, reports 3M, it can reduce magnet misalignment by virtually replacing liquid one- and two-part adhesives, which can move in an uncontrolled manner if inconsistent pressure is applied during the application and adhesive curing process. By providing adhesive in a tape form, magnets can be precisely positioned, or repositioned, if needed, because the adhesive can be metered through slitting and cutting or die cutting to reduce tendency toward adhesive squeeze out.

It also provides excellent control of the permanent magnet bond line thickness, which is critical to motor performance, the company notes. This distance, which is located between the inside diameter of the stator and the outside diameter of the rotor, is known as the air gap. Precisely controlling and minimizing the rotor-stator air gap can help allow a permanent magnet motor to attain a greater level of energy efficiency. Launched in 2016, it continues to find new applications and users, said the company.

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