How To Handle The Locking Problem Of Non-standard Screws And Precautions For Special Screw Materials

Non standard screws refer to screws that have corrosion resistance and are less prone to rusting in media such as gas and water. The quality of non-standard screws mainly depends on the requirements of specifications, mechanical properties, and surface defects. Widely used in the fields of environmental protection machinery, electronic equipment, food machinery and equipment, medical devices, etc. When locking occurs when using non-standard screws, the following handling methods can be taken:

Ensure the correct selection of screws: Before use, ensure that the screws meet the requirements of the device's functionality.

Pay attention to the quality of screw threads: If the threads of the screw are rough or contain dirt, such as welding slag or metal shavings sandwiched between the threads, it is easy to cause locking.

Control tightening force and speed: When tightening screws, excessive force or too fast tightening speed can cause the screw temperature to rapidly rise and cause locking.

Pay attention to the direction of reaction force: When tightening the screw, the screw cap should be rotated vertically and evenly along the centerline of the screw to avoid tilting.

Using washers and spring washers: When using screws, installing washers and spring washers can effectively prevent the problem of over tightening.

There are also some things to pay attention to when selecting materials for special screws:

Material selection for flat washers: For flat washers without mechanical performance requirements, edge materials such as Q235A can usually be used for manufacturing. If there is a hardness requirement but it is not high, thicker Q235A sheet metal can be used for rolling to achieve the required hardness.

Material selection for rivets and pins: Generally the same as screws, but some rivets cannot have too high hardness, and some even require a hardness lower than HRB60. The hardness of normal materials is generally between HRB70-80, so some rivets need to be annealed to meet performance requirements.

Material selection for special screws used for welding: There are generally no special material requirements for arc welding and gas welding. If the customer uses spot welding, low-carbon steel materials must be used. If strength needs to be increased, some low-carbon materials with higher manganese content can be used.

When a customer specifies the use of a specific grade of material, but the company temporarily does not have it or it is difficult to purchase the material in the market, it is possible to understand the customer's requirements for the use of special screws and submit a written application for material replacement on the premise of meeting the mechanical properties. Some purchasing customers may not be very professional about special screws, and the selection of materials may not be the best.

By properly handling locking issues and paying attention to the use of special screws, the effectiveness and quality of non-standard screws can be improved.