Rust Causes and Improvement Methods of Self tapping Screws

The so-called self-tapping screw: Simply put, it is a screw that can be tapped by itself, so it is suitable for fastening non-metallic or metallic components without the need for bottom holes and tapping. However, when such screws become rusty, it can affect the fastening effect. Therefore, we need to find the cause of rust and provide improvement methods.
Ordinary screws are generally flat headed and have the same thickness of the head, but self-tapping screws are pointed in order to achieve the "self tapping" effect. They can use their own thread characteristics on the consolidated material to achieve the corresponding thread effect by using the "tapping, drilling, squeezing, and pressing" process to tightly fix the consolidated body together.
This type of screw is mainly used for the connection and fixation between some relatively thin plates, such as the connection and fixation of color steel plates and color steel plates, the connection and fixation of color steel plates and purlins, the connection and fixation of color steel plates and wall beams, etc. Its penetration capacity is usually not more than 6mm, and some longer screws than special ones have a penetration force of not more than 12mm.
This type of screw usually needs to be exposed outdoors, so it has strong corrosion resistance. Moreover, the rubber sealing ring can also protect the screw connection from water seepage and prevent rust on the screw. Therefore, this type of screw has strong corrosion resistance.
This type of screw often combines a tap and a bolt, with the front part being the tap and the rear part being the thread. The surface hardness of screws is high, and the core toughness is good. It can be said that "internal flexibility and external rigidity" are a major feature of this type of screw.
If the surface hardness of the screw is relatively low and the toughness of the core is poor, it is easy to break it when screwing it, not only wasting the screw but also causing damage to the connector. Therefore, "internal flexibility and external rigidity" is the performance that this type of equipment should have.
When using this type of screw, you can drill a hole in the material to directly screw in the screw. By tapping the thread with a tap, the thread is immediately stressed. If the diameter of the screw is small, and the material of the plate to be fastened is relatively soft, even without the need for drilling in advance, simply screw the screw in.
The causes of screw rust are analyzed as follows:
1. Electroplating process issues. During electroplating, if the screws are not dried during the drying process, water vapor will remain. "Or it has been dried, but condensed water forms during the packaging process, leading to a chemical reaction between the water and the screw, causing the screw to rust.". In addition, if the plating is poor and the thickness of the plating layer is not up to standard, the corrosion resistance of the screw will become weak and easy to rust.
2. Storage or usage environment issues. During storage or use, poor environmental conditions can lead to screw rust, such as salinity, acidity, high salinity, high temperature, and high humidity, which can induce screw corrosion, oxidation, and rust.
The improvement methods are as follows:
1. Electroplating process. When electroplating, try to choose electroplating colors with a longer salt spray test time. Electroplating shall be carried out in strict accordance with the electroplating process, and the thickness of the electroplating layer shall be controlled. In order to improve the antirust ability, the screw surface can also be sprayed with antirust paint.
2. Storage environment. Place the packaged screws in a ventilated and dry environment, avoiding direct sunlight. The screws should be kept at a certain distance from the ground.
The reason why self-tapping screws rust is generally due to unqualified electroplating processes or poor storage and use environment. Therefore, to prevent screw rust, it is also necessary to start from these two aspects.