Coating and dripping paint process of hairpin motor stator manufacturing line

The copper wire of the flat wire hairpin motor must be elastic, but the rebound after bending must ensure that the insulation layer of the electromagnetic wire is not damaged; the flat wire insulation coating will shrink unevenly after drying, and it is easy to deform and become thinner at the four corners, affecting the insulation. It is necessary to improve the coating thickness at the R corner; the paint film coating at the R corner of the flat wire is difficult, and it is difficult to ensure the uniformity of the insulation layer; and after the flat wire is bent into a hairpin, the stress at the R corner is concentrated, which is easy to cause the coating layer to be damaged, so the accuracy and quality of the copper wire and its coating are very high. The dripping paint and coating process in the flat wire motor stator production line is to achieve fine coating of the product surface through high-precision motion control and angle control on the equipment. Its main function is to coat an insulating layer on the surface of the motor coil, thereby increasing the thickness and strength of the insulating material and improving the insulation and safety performance of the motor.

The advantages of the stator paint and coating process of flat-wire hairpin motors are mainly reflected in the following aspects:

Paint dripping: 

Form a uniform insulating layer on the surface of the winding to ensure that the entire winding surface is evenly covered, forming a consistent protective layer, and effectively preventing short circuits and leakage. At the same time, the paint layer also has moisture-proof and anti-corrosion functions, which can resist the erosion of moisture and corrosive gases on the motor windings, thereby extending the service life of the motor. In addition, it also increases the mechanical strength of the winding to prevent the winding from loosening due to vibration or mechanical stress.

Coating: 

Improve the insulation performance and effectively prevent partial discharge, thereby improving the reliability of the motor, and can also significantly enhance the mechanical properties of the winding and reduce wear and aging.

Paint dripping and coating production process flow in the stator production line of flat-wire hairpin motors:

Production process flow: 

preheating> coating> curing> coating unloading> weighing before dripping> scanning code before dripping> dripping paint loading> preheating> dripping paint> gel curing> unloading> weighing after dripping paint, etc.

Specific steps:

1. Preheating station to heat the furnace body.

2. Product weighing, the stator enters the paint dripping station to automatically drip paint. By adjusting the inclination angle of the stator, it can penetrate into the winding more quickly and evenly, ensuring the uniform distribution of the paint dripping, avoiding uneven paint dripping or dead corners, thereby improving the production quality of the motor.

3. After the paint dripping is completed, it is automatically cured in the furnace. After the curing in the curing furnace is completed, the manipulator grabs the stator to the secondary weighing platform, which helps to determine whether the stator has material loss or increase during the curing process, ensuring that its production process meets the predetermined standards.

5. After curing is completed, grab the stator to the coating station for coating. By coating a layer of insulating protective layer, it is ensured that the external humid air, dust and oil stains of the motor bearings cannot directly contact the coil, thereby ensuring the stability of the motor operation.

6. After the coating is completed, it is automatically cured in the furnace. After the curing is completed, the material is weighed and discharged to ensure that the weight change of the stator during the production process meets customer requirements.

There are currently two main types of coating materials: powder and liquid; the dipping process mainly includes traditional dipping, vacuum dipping, vacuum pressure dipping, drip dipping and other processes. The current mainstream process with high precision and stability is the drip process.

Main materials commonly used for coating

Epoxy resin

Epoxy resin (Epoxy Resin) refers to the general term for compounds that contain 2 or more epoxy groups in the molecular structure and can form a three-dimensional network solidified product in the presence of appropriate chemical reagents. It is an important type of thermosetting resin.

Epoxy resin can withstand temperatures up to 150°C and has high hardness and wear-resistant mechanical properties; the coefficient of thermal expansion (CTE) is close to that of the PCB substrate, and it is not easy to cause thermal stress failure due to the large CET gap during use; the glass transition temperature point is high; and it has good dielectric properties.

However, epoxy resin also has certain disadvantages in application, such as: high Cl ion content risk; difficult two-component ratio, difficult to maintain viscosity; potential high internal stress; difficult to rework; poor low temperature performance, and high curing shrinkage.

Silicone resin

Silicone resin, also known as organic silicone resin, refers to a compound containing Si-O bonds and at least one organic group directly connected to the silicon atom.

The advantages of silicone resin are wide operating temperature range, good flexibility, good moisture resistance and UV resistance, good dielectric properties, and good wettability with the substrate.

Its disadvantages are also obvious, low mechanical strength, not scratch-resistant, high CTE, and poor adhesion to the substrate. At present, sulfur corrosion occurs during the use of silicone resin.

Polyurethane resin

Polyurethane resin is a general term for macromolecular compounds containing repeated carbamate groups on the main chain.

The advantages of the material are good dielectric properties, good moisture resistance, good solvent resistance, and good scratch resistance.

The disadvantage is that the curing process and effect are affected by humidity, a long full curing process, and large changes in internal stress under high and low temperature changes. Pure polyurethane is expensive, so various modified polyurethane resins have emerged, such as polyurethane modified alkyd resins, polyurethane modified silicone resins, etc., and their performance also has certain advantages and disadvantages.

Poly-p-xylene resin

Poly-p-xylene resin (Poly-p-xylene), trade name Parylene, is a general term for polymer films with a p-xylene structure prepared by chemical vapor deposition.

The poly-p-xylene resin coating has no pinholes and good compactness. When the thickness reaches 7~8 μm, it has a good protective effect; the coating process does not require solvents and can accurately control the coating thickness; it does not absorb visible light, has excellent low temperature resistance, and has high electrical insulation performance and thermal stability.

However, its use equipment is expensive and the cost is increased. It is generally used in military enterprises and aerospace products.

With the continuous development of automation technology, the dripping paint process of the hairpin motor stator is also constantly innovating and optimizing.

Ningbo NIDE Tech Co., Ltd, adhering to the customer-centric concept, focuses on the stator, rotor and complete assembly of various motors, and provides customers with one-stop solutions for highly automated, intelligent and flexible production.

After years of development, NIDE has gradually accumulated a certain influence and brand effect at home and abroad. At present, the products cover the professional manufacture of new energy motor stator and rotor, hairpin motor, automatic aluminum casting rotor line, brushless motor/ BLDC motor, universal motor, wheel hub motor, etc., which are used in new energy vehicles, household appliances, industrial motors, water pump motors, servo motors, etc. The company integrates R&D, production and sales, and wholeheartedly serves customers at home and abroad, aiming delivering value and achieving a win-win situation.

The flat wire hairpin motor stator manufacturing line developed by NIDE not only helps customers improve production efficiency and reduce production costs, but also promotes the development and progress of the automotive motor industry.