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Why do motor windings need to be dipped in paint? What are the process flows?

Date:2023-10-24   Author:XINDA MOTOR

Motor dipping refers to dipping motor components, especially coils and other key components, into specific insulating paint to improve its insulation performance and durability. This process is designed to create a uniform layer of insulation inside and outside the motor to prevent leakage, short circuits or other electrical failures during operation.

Why does the motor need to be dipped in paint?

The motor is dipped in paint to improve the insulation performance and durability of the motor. This process is an integral part of the motor manufacturing process, and its main purpose is to form a uniform and strong insulation layer to protect the internal components of the motor from erosion and damage from external factors. Here are a few key reasons why motors should be dipped in paint:

1. Improve insulation performance: As an important electrical equipment, the insulation performance of motors is directly related to the safe operation of the equipment. Through the paint dipping process, a uniform insulation layer can be formed on the surface of the motor's coils and other key components, effectively preventing electrical faults such as leakage and short circuits.

2. Prevent the intrusion of moisture and pollutants : During use, the motor may be exposed to a humid environment or affected by pollutants such as dust and chemicals. The paint dipping process creates a sealed protective layer that prevents moisture and contaminants from entering the interior of the motor, thereby extending the service life of the motor.

3. Improve heat resistance: Some special insulating paints have good heat resistance and can remain stable in high temperature environments. Through the dipping process, the heat resistance of the motor can be increased, making it suitable for high-temperature working environments, such as industrial production lines and hot factory locations.

4. Improve mechanical strength: Appropriate insulating coating can improve the mechanical strength of motor components, increase its anti-seismic performance and anti-vibration capabilities, thereby reducing damage and failure caused by external forces.

Motor dipping process

The motor dipping process is a critical part of the motor manufacturing process and involves a series of steps and processes to ensure the motor's insulation performance and durability. The following is the general process of the motor dipping process:


Prepare motor components, including stator, rotor, coils, etc.

Clean the surface of the motor parts to make sure they are free of dust and oil.

Make sure the work area is tidy to reduce the impact of impurities on the coating.


Pre-treat the motor parts, such as baking or dusting, to ensure the surfaces are dry and clean.

Check the surface quality of motor components and repair possible defects or damage.

Paint preparation:

Prepare insulating paint to ensure its quality and performance meet relevant standards.

Stir the paint to ensure its ingredients are evenly mixed for a uniform coating.

Dip paint:

Dip the motor part into the paint bath, making sure the paint evenly covers the entire surface.

Control the dipping time and speed to ensure that the thickness and uniformity of the paint meet the requirements.

Drip dry:

Let the motor parts dipped in paint drip dry naturally or dry them by heating to ensure that the paint forms a uniform insulating film on the surface.

Prevent the paint from being contaminated during the drip drying process or being affected by external impurities.


Place the dried motor components in a specific temperature environment for curing.

Control the curing time and temperature to ensure that the coating is fully cured to form a strong insulation layer.

Quality inspection:

Conduct quality inspection on the motor parts that have been dipped in paint, including insulation performance testing and appearance quality inspection.

Ensure coating thickness, uniformity and insulation properties meet specification requirements.

How to dip paint on motor windings

1. Watering and soaking

When repairing a single motor, the windings can be dipped in paint. When pouring and immersing, place the stator vertically on the paint dripping tray with one end of the winding upward, and use a paint pot or paint brush to pour paint on the upper end of the winding. When the winding gap is filled with paint liquid and begins to seep out from the other end gap, turn the stator over and pour the other end winding. Until it is watered thoroughly. When repairing small motors sporadically, this method can reduce the waste of insulating paint.

2. Dripping

This method is suitable for dipping paint treatment of small and medium-sized motors. Units that lack special equipment can use manual paint dripping technology. The following introduces a commonly used paint dripping process for dipping the windings of small motors.

①Formula. 6101 epoxy resin (mass ratio), tung oil maleic anhydride 50%, ready for use.

②Preheat. Apply electricity to the winding and heat it for about 4 minutes, and control the temperature between 100 and 115°C (measured with a point thermometer), or place the winding in a drying oven and heat it for about 0.5 hours.

③Drip immersion. Place the motor stator vertically on the paint tray. When the motor temperature drops to 60-70°C, start dripping paint manually. After 10 minutes, turn the stator over and drip-dip the other end of the winding until it is thoroughly poured.

④Cure. After dripping, the winding is energized and solidified, and the winding temperature is maintained at 100~150℃; until the insulation resistance value is measured to be qualified (20MΩ), or the winding is heated in a drying oven at the same temperature as above for about 2 hours (depending on the size of the motor). Released when insulation resistance exceeds 1.5MΩ.

3. Paint roller

This method is suitable for dipping paint on rotor or armature windings. When rolling paint, pour insulating paint into the paint tank, place the rotor in the paint tank, and the paint surface should immerse the rotor winding by more than 200mm. If the paint groove is too shallow and the area of the rotor winding immersed in paint is small, the rotor should be rolled multiple times, or the rotor should be rolled while painting with a brush. Usually rolling it 3 to 5 times will allow the insulating paint to penetrate the insulation.

4. Immersion

When repairing small and medium-sized motors in batches, the windings can be dipped in paint. When immersing, first put an appropriate amount of insulating paint into the paint can, and then lift it into the motor stator so that the paint liquid submerges the stator by more than 200mm. When the paint liquid soaks into all the gaps between the windings and the insulating paper, lift the stator and drip the paint. When dipping paint, add 0.3~0.5MPa pressure. The effect is better.

5. Vacuum pressure immersion

The windings of high-voltage motors, as well as small and medium-sized motors with high requirements on insulation quality, can be vacuum pressure dipped. When dipping paint, place the stator of the motor in a sealed paint container and use vacuum technology to remove moisture. After the windings are dipped in paint, a pressure of 200 to 700kPa is applied to the paint surface to allow the paint liquid to penetrate into all the gaps in the windings and deep into the capillary pores of the insulating paper to ensure the quality of the dipped paint.

After the paint dipping is completed, place the stator on the wire mesh to allow the paint to drip cleanly, and wipe off the paint film on the surface of the stator core and the outer surface of the machine base with cotton cloth dipped in gasoline to avoid reducing the air gap and affecting the assembly of the rotor.

After the windings are dipped in paint and dry, do not use a wire brush to remove the paint film from the inner cavity of the iron core. Otherwise, once the steel wire on the wire brush is broken, a small section of the wire head may fall on the notch of the iron core. Especially when the wire brush is inserted into the edge of the slot wedge, if any broken steel wire remains, even with compressed air it will It cannot be blown off, and when the motor is running, the remaining wire ends will scratch the rotor. Therefore, it is prohibited to use a wire brush to remove the paint film from the inner cavity of the iron core.

The effect of temperature on the effect of dipping paint

Temperature is one of the important factors that affects the effect of motor dipping paint. It directly affects the viscosity, fluidity and curing speed of the paint, thereby affecting the quality and performance of the final insulation layer. The following are the main effects of temperature on the effect of motor dipping:

Paint viscosity and fluidity: Changes in temperature will affect the viscosity of the paint. High temperature will reduce the viscosity of the paint, thereby improving its fluidity, which is beneficial to the paint forming a uniform and dense insulation layer on the surface of the motor.

Cure Speed: An increase in temperature will cause the coating to cure faster, allowing it to form a strong insulating layer faster. However, if the temperature is too high, it may cause the paint to solidify too quickly, affecting the leveling of the paint and the density of the insulation layer.

Heat resistance of coating: The motor may be affected by higher temperatures during operation, so the coating after dipping needs to have good heat resistance to ensure the stability and durability of the insulation layer in high temperature environments.

Environmental condition control: In addition to temperature changes, factors such as ambient humidity can also affect the curing of the paint and the quality of the insulation layer. Changes in temperature may be accompanied by changes in humidity, so the ambient humidity needs to be controlled to ensure the quality stability of the dipping process.

The relationship between insulation dipping paint and winding dipping paint

Insulation dipping paint and winding dipping paint are both important processes in the motor manufacturing process. They are closely related. They are both designed to protect the insulation system of the motor and ensure that the motor can work safely and stably during operation. The relationship between them is mainly reflected in the following aspects:

Interdependence: Winding dipping paint refers to dipping the motor coil to form an insulating protective layer to enhance its insulation performance; while insulation dipping paint refers to dipping the entire motor components, including windings and other key components, so that the entire The motor forms a uniform insulation layer. The two complement each other and together form the insulation protection system of the motor.

Uniformity of the insulation layer: Through insulation dipping, the entire motor component, including the windings, can be covered with insulating paint to form a uniform insulation layer. This insulation layer can not only protect the windings from the external environment, but also improve the insulation performance of the entire motor to ensure the safe operation of the motor under complex working conditions such as high voltage and high temperature.

Synergy of insulation performance: Insulation dipping paint and winding dipping paint are both important means to improve the insulation performance of motors. Their synergy can effectively improve the voltage resistance, heat resistance and moisture resistance of the motor, thereby improving the safety of the entire motor. reliability.


In general, the motor dipping process is an important step to ensure long-term stable operation of the motor. It can protect the motor from the influence of the external environment and improve its safety performance and service life.