Bonding magnets with high-temperature adhesives

Structural adhesive offers temperature stability four times that of other adhesives in its class

DELO MONOPOX HT2999 is an adhesive with exceptionally high temperature stability. It achieves strengths of 20 MPa at 180 °C. This is four times greater than its predecessor. The product is primarily used in the automotive industry and mechanical engineering.

High-temperature-resistant adhesives are in particular demand for electric motors and power electronics. Many products show a clear drop in performance at temperatures above 150 °C. DELO’s structural adhesive can be used above that temperature.

Its performance profile has been optimized for bonding magnets in electric motors. For example, the compression shear strength of bonded magnets (NdFeB) is 20 MPa at 180 °C, with the bonded joints remaining thermally stable in the long term. Even after 1,000 hours of storage at 180 °C, they achieve a temperature stability of 20 MPa. The maximum operating temperature of electric motors is generally 180 °C since the powerful rare earth magnets will demagnetize at higher temperatures. If a certain application requires resistance at higher temperatures, DELO MONOPOX HT2999 can even be used up to 220 °C.

Electrical insulation is another important property of the adhesive. It minimizes eddy currents in electric motors, reducing heat development and increasing motor performance. DELO MONOPOX HT2999 is additionally provided with integrated spacers. They ensure a uniform and very thin bonding gap of 50 µm for magnet stacking. This allows the use of more magnetic material and also contributes to motor efficiency.

The one-component epoxy resin is gray and pasty. It takes just 10 minutes to cure in an air convection oven at 150°C. Compared to other high-temperature adhesives that require 30 to 40 minutes curing time at 150 °C, this adhesive offers clear advantages in saving time and energy.

For more information about bonding magnets and high-temperature adhesives, please visit our DELO Online Tech Talks

"New adhesives in e-motors: Bond strengths of more than 20MPa at +180 °C".