How to Design Stator Insulation Powder Coating Thickness?

During the manufacturing process of the motor, a layer of insulating material is sprayed on the stator surface through electrophoresis or electrostatic epoxy coating to ensure the insulation performance and durability of the motor. This process is stator epoxy coating. The stator insulation powder coating thickness generally ranges from tens to hundreds of microns.

What Is Powder Coating?

Powder coating involves applying a dry powder, typically epoxy resin, to surfaces needing insulation. Stator epoxy coatings tend to outperform paper and plastic overmolding.

Properties Of Powder Coatings

Powder coating provides a continuous layer of dielectric insulation with strong chemical and thermal resistance to protect motor coil windings.

Manufacture Process Key Steps

Preparation: The stator surfaces are cleaned and pre-treated to remove any impurities that could interfere with the adhesion of the powder.

Application: Electrostatic spray guns are used to evenly apply the powder to the stator. The powder is charged positively, and the stator is grounded to attract the powder particles.

Curing: After application, the stator is heated in an oven, which melts the powder and forms a uniform, solid film around the stator coils.

injection mold insulation for stator

Factors Affecting Powder Coating Thickness

The following factors mainly affect the stator powder coating thickness: motor type, power size, usage environment, insulation grade, etc. Among them, motor type and power size are the most important factors.

Generally speaking, the greater the power, the higher the insulation level required and the greater the thickness of the powder coating required. Similarly, different usage environments will also affect the thickness of the powder coating. For example, high temperature, humidity, and other environments will make the sprayed plastic layer thinner.

Designing the Right Powder Coating Thickness

Professionals utilize engineering calculations and simulations to determine the optimal insulation thickness. Consider factors like voltage stress, temperature rise, and insulation material properties. You can reference relationship between thickness and insulation voltage(Hi-Pot Testing), such as 0.1-0.2mm—-500V, 0.2-0.3mm—-600V, 0.3-0.4mm—-1000V, 0.4-0.5mm—-1500V, etc.

electrostatic epoxy coating insulation machine

Benefits of Proper Powder Coating Thickness

Enhanced Electrical Performance

Optimal insulation thickness minimizes the risk of electrical breakdowns and improves the motor’s overall electrical performance.

Improved Mechanical Durability

Thicker insulation provides better mechanical protection, ensuring that the motor can withstand vibration, shock, and wear over time.

Extended Motor Lifespan

Properly insulated motors tend to have longer lifespans, reducing maintenance costs and downtime.

Energy Efficiency

Efficient insulation helps maintain the motor’s efficiency, which can lead to energy savings over the motor’s lifetime.

Look for a stator core insulation China manufacturer

We have many automatic electrostatic epoxy coating lines to allow insulation of the iron laminated core.

Our capabilities to coat various specific powder classes(B, F, H) for motor laminations stacks up to 350mm outside diameter, with or without shafts.

The thickness of the coating could be 0.15mm – 0.6mm thickness.

We use materials 3M860, 3M266, 3M260、3M555、3M5230N, and the temperature resistance for the epoxy coating is 180 Degrees Celsius.

injection molding machine


The thickness of the stator powder coating plays an important role in the durability and insulation performance of the motor, but an excessively thick coating may also affect the heat dissipation and mechanical performance of the motor, which needs to be considered comprehensively when designing and manufacturing the motor.


Can excessive insulation thickness have negative consequences for motor performance?

Yes, excessive insulation thickness can indeed have adverse effects on motor performance. While it’s essential to provide adequate insulation for the motor windings, an excessively thick insulation layer can lead to several problems.

Firstly, it can hinder heat dissipation, causing the motor to operate at higher temperatures and potentially leading to overheating.

This, in turn, can degrade the insulation material and shorten the motor’s lifespan. Moreover, thicker insulation can increase the winding’s resistance, reducing the motor’s overall efficiency and power output.

What is the primary purpose of stator insulation powder coating?

The primary purpose of stator insulation powder coating in electric motors is to provide a protective barrier for the motor windings. This coating serves as a crucial safeguard against electrical short circuits, preventing unintended contact between the winding conductors and the motor’s iron core.

By isolating the windings from the core, it ensures the motor’s electrical integrity and reliability. Stator insulation also plays a vital role in enhancing electrical performance by minimizing electrical losses and leakage currents.

Additionally, it offers mechanical protection, shielding the windings from vibrations, shocks, and wear and tear, which can occur during motor operation.

Can Electrostatic Epoxy Coatings Withstand High Temperatures?

Electrostatic epoxy coatings have excellent thermal stability, making them suitable for applications that involve exposure to high temperatures. These coatings can withstand temperatures ranging from approximately -40°C to 150°C (-40°F to 302°F) and, in some cases, even higher. 

Their ability to endure elevated temperatures without degrading or losing their protective properties makes them a preferred choice for a wide range of industries, including automotive, electronics, and aerospace. 

Try to contact us for high-quality motor cores in China.