Tip Gap: How to adjust the gap between the "Waterproof Cooling Fan" fan frame that exists and is a big fan of the design problem. Here the gap is too small will make the airflow and the blade, frame friction, noise increases; the gap is due to the increased air flow, such as the impact of the flyback reduce fan efficiency.
Leaves smoothness: "Waterproof Cooling Fan" is a non-target design factors, basically depends on the forming mold producers and post-processing technology. In addition to the design curve is not flat blades will produce turbulence in the rotation, increasing friction, reduce fan efficiency impairment "Waterproof Cooling Fan" performance, increased operating noise.