There are currently two ways to connect the aluminum alloy outer frames on the market: 45-degree corner joining and 90-degree straight splicing with threaded fastening. 

The causes and solutions for water leakage in 45-degree corner joining: 

1. When cutting materials, if the 45-degree cutting angle is incorrect or the saw blade is severely worn and has poor dynamic balance, it will cause gaps or depressions at the 45-degree corner joint, leading to water leakage. Solution: Improve the cutting accuracy of the equipment and frequently replace the saw blades.

2. When corner joining, if the fit gap between the corner code and the frame material is too large, it will cause looseness or gaps at the 45-degree joint after corner joining, resulting in water leakage. Solution: It is recommended to control the fit gap between the corner code and the material cavity within 0.2mm, and add reinforcing ribs at the force point where the corner code is in contact with the extrusion die.

3. If the 45-degree joint surface is not coated with sealant during the 45-degree corner joining, water will directly flow into the cavity along the 45-degree joint surface and seep into the wall. Solution: Apply sealant on the 45-degree joint surface before corner joining, preferably a sealant with certain elasticity and extensibility.

4. If sealant is not injected into the cavity at the corner after corner joining, the overall strength and sealing performance of the corner will be insufficient, and water will directly seep in when there is water. Solution: After corner joining, inject sealant into the cavity at the corner, preferably polyurethane two-component corner joining sealant. This sealant, being two-component, does not need to absorb moisture from the air during the drying process and will dry in a sealed environment. Moreover, after drying, it becomes a hard sealant, which can increase the strength of the corner by 3 to 5 times and has excellent sealing performance.

5. If the cavity of the insulating part of the thermal break profile is not treated, water will directly enter the corner from this section and seep out. Solution: Design a special connecting piece for the insulating gasket cavity and use injection sealing.

6. At the large surface flange of the profile (especially for interior doors and windows), if the corner connecting piece is not installed, there will be misalignment or gaps at this location due to the absence of a corner code, resulting in water leakage. Solution: Design a corner connecting piece that matches the corresponding slot and inject sealant at the corner.