What is the rationale behind establishing a minimum and maximum operating temperature limit for the cooling fan?

1. The thermal sensitivity of the motor: The core component of a Cooling Fan is the motor, and its coil and magnet exhibit significant sensitivity to temperature variations. At low temperatures, the motor lubricant may become viscous, increasing starting resistance and potentially leading to difficulties in motor startup or overloading. At high temperatures, the insulation material of the motor may degrade, thereby increasing the risk of short circuits. For instance, at -10°C, the viscosity of the lubricant increases by approximately 30%, resulting in a higher starting current.  
2. Thermal expansion and contraction of materials: Fan blades and frames are typically constructed from plastic, metal, or other synthetic materials. These materials undergo expansion or contraction in response to temperature fluctuations. Extremely low temperatures can render the material brittle, increasing the likelihood of cracking. Conversely, extremely high temperatures may cause material deformation, which could affect the balance and efficiency of the fan. For example, the hardness of aluminum alloys increases by roughly 15% at -40°C compared to 20°C, whereas deformation may occur at 100°C.

3. The viscosity of lubricating oil in Fan Bearings varies with temperature changes.

At low temperatures, the lubricant may become excessively viscous, leading to increased bearing friction and reduced fan rotational speed. Conversely, at high temperatures, the lubricating oil may become too thin, compromising its lubrication effectiveness and accelerating bearing wear. For instance, at -20°C, the viscosity of the lubricating oil is approximately twice that at 20°C.

4. Additionally, air density and flow efficiency are critical factors affecting fan performance. As temperature decreases, air density diminishes, reducing airflow and heat dissipation efficiency. Consequently, fans may fail to provide adequate cooling at low temperatures. At high temperatures, the heat capacity of air increases, requiring fans to expend more energy to move the same volume of hot air. For example, air density is roughly 8% lower at 0°C compared to 40°C.

5. Tolerance of Circuits and Electronic Components  
The cooling fan incorporates circuits and electronic components with a defined temperature tolerance range. Operation at low temperatures may lead to a reduction in the response speed of circuit components, whereas high temperatures can result in degraded performance or potential damage to the components. For instance, the response time of certain semiconductor components is 30% slower at -40°C compared to 25°C.

If you have further requirements or inquiries regarding cooling fans, please do not hesitate to contact Fuqingda Electronic Technology Co., Ltd. Our cooling fans are designed to operate efficiently within a temperature range of -20°C to 70°C and can be tailored to meet specific customer specifications.