Most products are mainly waterproof for upper and lower shells, keys, battery doors and sensor leads. Common waterproof methods include gluing, ultrasonic, secondary injection molding, inserting inserts and installing O-rings The main causes of poor waterproof are plastic deformation; The water surface is not in a line; O-ring preloading is too loose or too tight; Insufficient structural stiffness; Uneven distribution of screws or sliding teeth, etc
1.The disadvantages of plastic deformation are obvious
There are also many methods to prevent deformation, such as improving the rubber mouth, transporting water, strengthening the bone, increasing the demoulding slope, etc For some products, the deformation is mainly caused by the deformation of the front and rear shell surfaces due to shape constraints, or the large change of the wall thickness of plastic parts due to too small internal space.
2.The water surface is not on the same surface
The surface on which the O-ring is placed is an irregular curved surface. When the upper and lower covers are buckled, the waterproof line is not easy to be connected. Most of such waterproof effects are not good Ultrasonic treatment with similar shape is not effective and should be avoided as much as possible To ensure the continuity of the waterproof line, try to make the waterproof line intersect a single plane with a single plane (or curved surface).
3.Uneven distribution of screws or sliding teeth
Uneven screw distribution will cause the O-ring preload to be too loose or too tight Of course, the O-ring is partially loose, which is not waterproof, but the tighter it is pressed, the better. If it is pressed too tightly, it will exceed the yield strength of the O-ring. When the product passes the high and low temperature test, the O-ring loses its elasticity.
4. The outgoing line is waterproof
Since the outgoing lines of some electrical components shall be connected with the circuit board after additional processing, such a structure can adopt the box structure, that is, the components of each part to be waterproof shall be assembled separately, and then the parts shall be wrapped together with an outer cover.
Therefore, the waterproof structure design of products should be designed in strict accordance with relevant standards. In addition, more reasonable waterproof design methods should be considered when designing for different products.
Appendix: IP Rating Standard Chart