The rotor is a key component of motor products. In general, the rotor is composed of a rotor core and a shaft, whether it is a cast aluminum rotor or a winding rotor, its surface must be turned and, if necessary, grinding.
The rotor that has just been turned will have a beautiful metallic color, but if the environment is wet, or if it is placed for too long, there will be obvious rust on the surface of the rotor, which will have an adverse effect on both the rotor appearance and the motor performance.
In order to prevent the surface of the rotor core from rusting after machining, the surface is painted to prevent rust. The anti-rust on the surface of the rotor, on the one hand, is the protection requirement in the process of motor production and processing, on the other hand, after the motor is stopped, due to changes in temperature, condensation appears in the inner cavity of the motor, which will also lead to corrosion on the surface of the rotor.
In view of the above reasons, different motor manufacturers will use different colors to paint the rotor surface, protection also increases the industrial beauty of the rotor, and some motor manufacturers do more in place, through the difference in rotor color, as a process processing logo, different colors represent different series, of course, can also give other meaning.
<h1 class="pgc-h-arrow-right" > cause of condensation</h1>
Humidity is divided into absolute humidity and relative humidity. Absolute humidity refers to the quality of water vapor per cubic meter of air. Condensation refers to the phenomenon of condensation on objects with relatively low temperatures when water vapor reaches saturation in the air. Condensation is a special phenomenon when the humidity reaches a certain level.
The composition of air can be regarded as composed of three parts: absolutely dry air, water vapor, and layers. Absolute humidity is the quality of water vapor per unit of air at a certain pressure and temperature. Saturated humidity is the maximum moisture mass that can be contained per unit of air under that condition. The higher the temperature, the more water vapor can be contained in the air, and the greater the saturated humidity. The ratio of absolute humidity to saturated humidity is relative humidity. If the humidity of the air is maintained and the air temperature is reduced, when the temperature is low to a certain value, the partial pressure of the water vapor reaches the saturation pressure corresponding to the air temperature at that time, and the water vapor in the air under this condition reaches saturation. If the air temperature is further reduced, the water vapor will condense and precipitate from the air to form "dew droplets". This phenomenon is called "condensation".
The reason for the occurrence of product condensation phenomenon in the temperature test is that when the ambient temperature in the test chamber rises, due to thermal inertia, the temperature of the product surface is lower than the ambient temperature, and when the humid and hot ambient air encounters the product surface below the dew point, the water vapor will condense on the surface to form dew droplets. Moreover, if the product is sealed, when the ambient temperature in the test chamber is reduced, the temperature of the inner wall of the product shell cools down faster than the air temperature in the cavity, and the humid and hot air in the cavity will also condense into dew droplets on the inner wall of the product shell. Since most products are not completely sealed, condensation phenomenon generally occurs in the heating stage.
The condensation effect is related to the material used in the product, the size of the cavity, the temperature rise and fall rate, and the relative humidity. The worse the heat absorption of the material, the larger the cavity, the faster the temperature rise rate, and the greater the relative humidity, the more severe the condensation effect. As long as any one of the conditions under which condensation occurs is destroyed, condensation can be prevented.
Under normal circumstances, the inherent properties such as the material used in the product, the size of the cavity and the upper limit of temperature stability, the lower limit of temperature stability and the rate of temperature rise and fall used in the test have been determined in advance.
The above unofficial content is only a personal opinion.