There are various materials for screws, and the following are some common types and their characteristics: Carbon steel: It is relatively inexpensive and is one of the widely used screw materials. Has high strength and hardness, and can withstand large tensile and torsional forces. The disadvantage is poor corrosion resistance and easy rusting, which usually requires surface treatments such as galvanizing and nickel plating to improve rust prevention ability. Stainless steel: It has excellent corrosion resistance and oxidation resistance, and can maintain good performance in harsh environments such as humidity, acidity, and alkalinity. Beautiful appearance, not easy to rust, can maintain a bright surface for a long time. The strength and hardness vary depending on the type of stainless steel. Generally speaking, austenitic stainless steel has better corrosion resistance but relatively lower strength; Martensitic stainless steel has higher strength and hardness, but its corrosion resist...

Common ones include carbon steel, which has a relatively low price and high strength, but poor corrosion resistance. It generally requires surface treatment such as galvanizing, nickel plating, etc. to improve its rust prevention ability. Stainless steel has good corrosion resistance and oxidation resistance, suitable for various harsh environments, but its strength may be slightly lower than carbon steel. Copper screws have good conductivity and thermal conductivity, as well as good corrosion resistance, and are commonly used in environments that require conductivity or chemical corrosion. There are also alloy steel screws, which can achieve higher strength, toughness, wear resistance and other special properties by adding different alloy elements. They are suitable for applications that require high screw performance, such as aerospace, automotive engines and other fields.

One is vibration, during the operation of the equipment, the screws will be subjected to alternating stress due to vibration, causing them to gradually loosen. The second issue is insufficient torque during installation, which does not reach the specified tightening torque, making the screws prone to loosening during use. The third is temperature change. In environments with significant temperature changes, screws and connected parts will undergo varying degrees of deformation due to thermal expansion and contraction, leading to screw loosening. The fourth issue is thread wear. Long term use or frequent disassembly may cause screw thread wear, affecting its fastening performance and leading to loosening.

You can try dropping some rust remover, such as WD-40, on the screw first, allowing it to penetrate for a period of time to soften the rust, and then try to unscrew it with a suitable tool. If the screw head is damaged and cannot be turned with conventional tools, you can consider using a wire cutter to ｉｎｓｅｒｔ it into the center hole of the screw head, and then remove the screw by reverse rotation. In addition, heating methods can also be used, such as using a blowtorch or other tools to heat around the screw, causing it to expand due to heat, and then quickly cooling it with cold water. The principle of thermal expansion and contraction can be used to loosen the rust layer before attempting to unscrew the screw. However, this method requires careful control of temperature and heating time to avoid damaging surrounding components.

Firstly, it is necessary to ensure that the installation surface is clean, flat, free of debris and oil stains, so as not to affect the tightening effect of the screws. Choose appropriate tools, such as screwdrivers, wrenches, etc., to ensure that the tools match the screw heads and avoid damaging them. When screwing in the screw, keep it perpendicular to the installation surface and avoid tilting it in, otherwise it may cause the screw to not be fully screwed in or damage the thread. For situations where specific torque is required, a torque wrench should be used to tighten according to the specified torque value to ensure the reliability of the connection and prevent screw breakage or damage to the connected parts due to excessive torque.

Multiple factors need to be considered. If it is used to fasten wood, wood screws are a common choice, with thicker threads that can better bite into the wood. In metal connections, mechanical screws are commonly used. Depending on different strength requirements, there are different materials and grades, such as carbon steel, stainless steel, etc. Stainless steel screws have strong corrosion resistance and are suitable for humid or corrosive environments. For applications that require high-precision connections, such as electronic devices, precision screws may be used. In addition, the size, length, and head shape of the screw should also be considered. For example, countersunk screws can make the surface flat, while semi-circular screws have a more rounded appearance.