The typical design of E-Drive rotors involves submerged permanent magnets located in a V-shaped pattern inside the rectangular cavities of a stacked rotor. The challenge is: any space between the components will allow for vibration which may lead to chipping or breaking of brittle magnets. In addition, the space also causes noise and vibration. Adhesives could reduce the noise and vibration due to their viscoelastic properties. However, they are not easy to apply in the common designs.

Henkel’s solution introduces material that expands by 70 % during curing and thus compensates for manufacturing tolerances in the electric motor. The expanding adhesives fill the space between the permanent magnet and the rotor package and fixes the magnet securely in position.

The adhesives feature high temperature resistant epoxy (Tg 120 °C ). It is a 1-component material either in solid or in liquid state and could be applied by dispensing or as “dry to touch” parts, e.g. by pre-applying it on the narrow side of magnets. The solid material can have different shapes with films down to 0.8 mm.

• Loctite EA 9536 (fully commercialized): Solid, flexible non-tacky film, shore hardness (durometer A) 40 [insert Link]
• Loctite EA 9537 (in development): Pumpable liquid epoxy, viscosity 120 Pa.s, expands at temperatures > 150 °C by 70 %, Cure: > 170 °C, typically 20 min at 180 °C at bond line, Glass transition temperature Tg: 120 °C

More about Henkel:
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Henkel operates globally with a well-balanced and diversified portfolio. The company holds leading positions with its three business units in both industrial and consumer businesses thanks to strong brands, innovations and technologies. Founded in 1876, Henkel looks back on more than 140 years of success. The DAX-40 company has its headquarters in Düsseldorf, Germany. Henkel employs about 53,000 people worldwide, around 85 percent of whom work outside of Germany. As a recognized leader in sustainability, Henkel holds top positions in many international ratings and rankings. The business unit Adhesive Technologies is the global leader for adhesives, sealants and functional coatings and provides high-impact solutions across more than 800 industry segments including Automotive under well-known brands like Loctite, Teroson or Bergquist. Henkel's E-Mobility division offers a wide variety of solutions which are specifically designed to optimize the design, assembly, performance and reliability of EV Battery Systems, such as: Thermal Interface Materials, Thermal Propagation Prevention Materials, Adhesives & Sealants, and Functional Coatings.
 

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