Bonding Ferrite Core Halves for Transformers
Adhesives have several advantages in joining ferrite halves over mechanical clips. Adhesives help reduce weights as well as help reduce rattle and hum in transformers. Different types of adhesives can be used for this depending on the manufacturer’s needs and process. One component epoxies are typical. UV cure adhesives and two-component epoxies are also heavily used for ferrite core bonding.
One Part Epoxies
One component epoxy adhesives are used extensively in ferrite core bonding due to its ease of use, versatility, and fast cure times with heat. Many one component epoxy adhesives can cure in minutes with heat creating extremely high bond strength. It is straightforward to control dispensing process using one component epoxies due to its availability in packaging as well as long work life. Glass spacer beads can also easily be added to one component epoxies to control gap space.
UV Cure Adhesives
UV cure adhesives offer a number of advantages for bonding ferrite cores. UV cure adhesives can offer very strong bonds and cure within seconds of exposure to UV light. Typically, ferrite cores must be assembled and the UV adhesive is applied to the joint of the ferrite core halves and cured within seconds. UV cure adhesives are available in easy to use disposable syringes (typically 10ml or 30ml) which are ideal for high speed dispensing systems.
Two part and one part, low viscosity epoxies are used extensively for coil impregnation and encapsulating copper coils. These materials need to be able to vacuumed into the coil and take up all empty space in the transformer coil to reduce noise and protect the coil. These epoxies can be filled or unfilled but need to be low viscosity. Depending on the transformer, high heat resistance may be needed which would call for a one component epoxy or a heat cure two-component epoxy.