It turns out that the poor sealing performance of doors and Windows is all due to the hardware!
There are many types of hardware for doors and windows that affect their sealing performance. Based on their impact on sealing, they can generally be divided into two categories: multi-point locking hardware and single-point locking hardware. The influence of door and window hardware on air tightness should be given sufficient attention by manufacturers.
Multi-point locking hardware features locking points and strike plates distributed around the entire perimeter of the door or window. When locked, these points and plates firmly engage with each other, working in conjunction with hinges or sliding supports to generate strong sealing pressure. This compresses the weatherstripping, providing excellent sealing performance and integrating the sash and frame as one. Thus, multi-point locking hardware significantly enhances the sealing performance of doors and windows. In contrast, single-point locking hardware offers much poorer sealing performance. Since it only provides a single locking point on the opening side of the door or window, working with hinges or sliding supports creates only 3-4 locking points. This leaves the four corners of the door or window unconstrained, resulting in gaps between the two unconstrained corners and the locking point, severely compromising the sealing performance.
Taking the arrangement of locking points on the handle side as an example: assuming the window width is B, height is H, and sash bending stiffness is E×I, we analyze three scenarios—single locking point, two locking points, and three locking points (with locking points positioned no less than 0.1mm from the sash edge). Using mechanical formulas, the maximum deformation values on the handle side in the sealing direction are calculated for each case. The results show that using three locking points significantly reduces sash deformation and improves sealing performance. Of course, while meeting strength and sealing requirements, excessive locking points should be avoided to prevent unnecessary waste.
Similarly, most hinges used in doors and windows require cutting away the weatherstripping at the hinge location during installation. But has anyone considered the impact of this on air tightness? In fact, the air leakage caused by removing the weatherstripping negatively affects energy efficiency, yet this issue is often overlooked.
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