Factors affecting the effect of impregnating paint
(1) Surface requirements of the impregnated parts. The surface of the clean and dry parts is good for the infiltration of the paint. If the impregnated parts are greased and dirty, the surface is not conducive to the infiltration of the paint, and it also causes different degrees of contamination of the impregnated paint. In particular, powdery debris in the core may cause fatal electrical failure of the windings.
(2) Characteristics of the impregnating varnish itself. The wettability of the impregnating varnish is closely related to the quality effect after the component is immersed. If the immersion property of the varnish is excellent, it will ensure that the fine gap is completely filled, otherwise it is necessary to overcome the existence between the liquid and the solid insulating surface by pressure. Inherent repulsive force, which affects the insulation treatment effect. VPI equipment has this capability to perfectly achieve the sufficiency of the winding immersion paint.
Wetting is the degree of wetting of a solid surface by a liquid, expressed as a wetting angle. The wetting angle is the angle between the tangent to the liquid phase at the point where the solid-liquid two phases are in contact, and the tangent to the solid wall. The smaller the wetting angle, the better the wetting; the greater the wetting angle, the worse the wetting. The wettability liquid is a concave liquid surface in the capillary, and the non-wetting liquid is a convex liquid surface in the capillary. Here, it is specifically the ideal effect of better contact bonding between the impregnating varnish and the impregnated article.
(3) Adhesives for composite insulation materials. The compatibility of the adhesive in the composite material used in the machining of the motor windings with the compatible impregnating varnish is particularly important. If the two are incompatible, it will affect the spreading ability and infiltration effect of the lacquer on the surface of the solid material.
(4) Viscosity of the impregnating varnish. When the viscosity of the paint increases, as the surface tension increases, the wettability of the paint is lowered, which affects the penetration ability of the paint.
Effect of temperature on dipping paint and evaluation of effect
● Temperature and impregnating varnish penetration and wetting
Under the same impregnation conditions, the small viscosity easily permeates and wets the surface of the impregnated insulating material, and the viscosity is large and it is difficult to penetrate and infiltrate. As the temperature increases, the viscosity of the impregnating varnish decreases, so in the actual insulation treatment, choosing the proper temperature of the impregnating varnish is essential for achieving satisfactory insulation treatment.
● Temperature and filling ability of impregnating varnish
The filling ability of the impregnating varnish depends mainly on the solids content of the lacquer. Therefore, it is generally required that the impregnating varnish has a high solid content, so that the paint has a good filling property. Since the solid content of the same batch of impregnating varnish is the same, in the case of a certain solid content of the impregnating varnish, the higher the temperature, the lower the viscosity, and the lower the solid content of the impregnating varnish per unit volume; The lower the lower the solid content of the impregnating varnish per unit volume.
● Factors affecting the wettability of the impregnating paint
1) The surface condition of the parts is clean and dry, which is beneficial to infiltration, oil and dirt are not conducive to infiltration; 2) the characteristics of the impregnating paint itself; 3) the compatibility of the adhesive of the insulating material of the dressing part and the impregnating paint; 4) the impregnating paint Viscosity; 5) temperature.
● Evaluation of impregnation and drying effect
Many motor manufacturers use the amount of paint to evaluate the effect of dipping paint, but Ms. believes that if the paint is too sticky, its penetration ability will be poor. The final effect is to form a thick shell on the surface of the winding. In fact, the curing effect is actually achieved; on the contrary, if the paint is too thin, the permeability will be good, but it is not easy to hang on the winding, and the curing effect is also not achieved.
For this reason, different motor manufacturers pay special attention to this process, but different motor manufacturers will refine and verify the process parameters such as pre-baking, dipping and drying according to their comprehensive factors such as products, equipment and materials. Bringing on the facts does not necessarily meet the quality requirements of its own products.
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