Why encapsulating electric motor with epoxy resin?

The electric motors encapsulation is becoming more and more commonplace due to the rapid ongoing development of EV and HEV technologies.

The Benevelli Group in recent years has acquired successes in the encapsulation of traction motors for fully electric and hybrid vehicles.

The use of vacuum encapsulation technology is becoming increasingly essential to provide the best protection and increased performances of the electric motor.

With the formulation and application of a suitable resin, it is possible to guarantee thermal dissipation of the motor and a greater resistance to shocks, vibrations, chemical agents, water, dust and other external agents.

Key Benefits


    First advantage is to obtain an excellent electrical insulation, in fact air or voids can create partial discharges between ground and primary insulation, compromising the performances and the motors lifetime. Thanks to the of vacuum casting, the resin will spread into all internal spaces of the motor (especially into undercuts and windings). In this way a perfect insulation is granted.


    Secondly the encapsulation is useful to obtain High Thermal Dissipation, in fact the cured resin is a great thermal conductive material. This means that motors work at lower temperature and therefore they have higher endurance.


    Your electric motor will have a so long life! The resin protects from chemicals, humidity, dust and bumps. Moreover, the resin reduces drastically the vibrations and the noise produced by the motor and it gives an important structural reinforcement, donating a greater mechanical stability.


    Thanks to some Epoxy resins it’s possible to have flame retardant properties, an additional benefit for onboard applications like electric vehicles and marine transportation. Some variety of epoxies and polyurethanes are designed in fact with fire-retardant properties. This protects any encased product or part while ensuring normal, stable operation.


    The last but not least, the latest Norms are restricting chemical emissions at the chimney. The emissions quantity of chemicals is different from type to type: Solvent based Varnishes has 50-70% of emissions (it means that the solid content value is only 30-50% max). For Polyester resins depends on the resin type, 3% (acrylates) - 25% emissions (styrene based polyesters).

SMAC Serie electric motors are encapsulated with epoxy resin

Know More

Since decades thermosetting resin systems based on epoxy and polyurethane have found widespread industrial applications. In the electrical and electronic industry these materials are well established because of the excellent mechanical and electrical properties, the thermal durability, the chemical resistance and easy processability.

Emerging challenges for the development of motors and generators for industrial and automotive applications are size reduction, higher integration density, more power output, higher reliability and endurance, resistance in harsh environment as well as noise reduction.

Simple varnishing the rotor and stator windings is commonly used for electrical insulation and mechanical fixation but these parts do not fulfill higher requirements.

An electric motor stator encapsulate method, including arranging a stator of an induction motor in a case of the induction motor, wherein the stator comprises a stator core and a stator winding surrounding the stator core; filling a first encapsulating material into the case for forming a first insulation layer, wherein the first insulation layer directly covers the stator winding; and filling a second encapsulating material into the case for forming a second insulation layer, wherein the second insulation layer covers the first insulation layer; wherein a shrink rate of the first encapsulating material is smaller than a shrink rate of the second encapsulating material.

About SMAC Serie

In recent years, the emerging electric vehicle market, extent rising rare-earth magnet costs, have boosted demand for interior permanent magnet (IPM) motors.

With advantages like constant power over a broad speed range and a magnet-retaining design, IPM motors provide a good solution for applications like traction motors and machine tools.

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