A common application for epoxy potting and encapsulating materials is coil impregnation in electrical transformer manufacturing. Transformer coils are encapsulated for a variety of reasons including:
- Increase dielectric strength
- Improve the structural integrity of the coils
- Reduce or eliminate winding noise
- Improve heat transfer
- Reduce partial discharge
- Provide increased environmental protection
Why use epoxy when needing to encapsulate coil windings in transformers? Epoxy potting and encapsulating compounds offer the best combination of adhesive strength and noise dampening capability. Furthermore, epoxy systems are also easily modified for viscosity reduction, thermal conductivity, and a variety of curing options. As a result, epoxy systems in combination with vacuum impregnation is a common choice for encapsulating coils. In these situations a vacuum is utilized to remove as much air as possible and replace it with epoxy. This is ideal with a low viscosity epoxy to be able to impregnate the coil winding which can many times be very tightly wound.
The types of epoxy potting compounds can vary depending on the size and type of coil however some properties that are generally always needed are low mixed viscosity, good dielectric strength, high bond strength, high operating temperature, and good sound dampening. Low exotherm, long pot life two component systems containing special fillers, modifiers, pigments can be automatically dispensed through meter mix equipment and cured at low temperatures while preventing any air bubble formation, pin holes, imperfections, cavities.
Engineers evaluate potting compounds using a variety of factors. They consider all physical and process properties in relation to the application. We have a variety of options for engineers to choose from. Furthermore, we can develop and customize a product for specific applications. We have experience in matching products to applications resulting in lower engineering time. For fully automatic vacuum casting systems for the high-volume production of ignition coils a viscosity stable epoxy is key so the perfect amount is filled each time. A video of a fully automatic process can be seen here.