Product Details of Combined Screws ## I. Product Overview Combined screws are fastening connectors that combine screws with other accessories such as flat washers and spring washers. This combined design eliminates the need to separately find and install washers during installation, greatly improving work efficiency and widely used in various industries such as electronics, machinery, and furniture. ## II. Product Types and Specifications### (I) Types 1. Ordinary Combined Screw: Consists of a screw, flat washer, and spring washer. The flat washer mainly serves to increase the contact area and distribute pressure, while the spring washer provides anti-loose functionality to prevent the screw from loosening under vibration or other conditions. 2. Nut-equipped Combined Screw: In addition to the screw, flat washer, and spring washer, a nut is also equipped. This combination is suitable for applications requiring a stronger connection, and the tightening of the nut can further enhance the stability of the connection.### (II) Specifications 1. Screw Diameter: Common screw diameters include M2, M2.5, M3, M4, M5, M6, etc., and the appropriate diameter can be selected based on different usage scenarios and connection needs. 2. Screw Length: The length ranges from a few millimeters to tens of millimeters, such as 6mm, 8mm, 10mm, 12mm, 16mm, 20mm, etc. The selection of screw length depends on the thickness of the connected object. 3. Head Type: Includes various types such as countersunk head, pan head, cylindrical head, hex head, etc. Countersunk screws are suitable for applications requiring a flat surface; pan head screws have a larger head and wider force-bearing area, commonly used for general fastening connections; cylindrical head screws have a cylindrical head, providing a more aesthetic appearance; hex head screws are convenient for tightening with tools such as wrenches. ## III. Product Features### (I) Convenient Installation Combined screws combine screws and washers in advance, eliminating the need to separately install screws and washers during installation, reducing installation steps and saving time and labor costs.### (II) Good Anti-loose Performance The presence of spring washers ensures good anti-loose performance of combined screws. In vibration or impact environments, the spring washer can provide continuous elastic pressure to prevent the screw from loosening, ensuring the reliability of the connection.### (III) Strong Versatility Combined screws come in various specifications to meet the connection needs of different industries and equipment. Whether it is precise connection of small electronic devices or fastening installation of large machinery, suitable combined screws can be found.   ### (IV) Aesthetic and tidy combination The combination design of combination screws makes the connection parts more tidy and aesthetically pleasing, avoiding issues such as gasket displacement and loss that may occur when using screws and gaskets separately. ## IV. Product Materials ### (I) Carbon Steel Carbon steel is one of the most commonly used materials for combination screws, with high strength and hardness and relatively low cost. According to different carbon contents, carbon steel can be divided into low carbon steel, medium carbon steel, and high carbon steel. Low carbon steel combination screws have good toughness and are suitable for applications where strength is not a major requirement; medium and high carbon steel combination screws have high strength and are commonly used for connections that bear large loads. ### (II) Stainless Steel Stainless steel combination screws have good corrosion resistance and are suitable for wet, corrosive environments or applications where appearance is highly important. Common stainless steel materials include 304 and 316, with 316 stainless steel having stronger corrosion resistance. ### (III) Copper Copper combination screws have good electrical and thermal conductivity and are commonly used in the electronics and electrical appliance industry. Common copper materials include brass and red copper. Brass combination screws have high strength, while red copper combination screws have better electrical conductivity. ## V. Production Process ### (I) Cold Heading Process Cold heading is one of the main processes for producing combination screws. Metal wire is headed into screw heads and shanks at room temperature using a cold heading machine. This process improves the strength and precision of the screws and has high production efficiency. ### (II) Thread Rolling Process Thread rolling is the process of processing threads on the shank of the cold-headed screw. A thread rolling machine extrudes threads on the screw shank to ensure thread precision and surface quality. ### (III) Assembly Combining the cold-headed and thread-rolled screws with gaskets. During the assembly process, it is important to ensure that the gasket is installed in the correct position and that the assembled screw meets quality requirements. ### (IV) Surface Treatment To improve the corrosion resistance and aesthetics of combination screws, surface treatment is usually applied. Common surface treatment methods include galvanizing, nickel plating, and blackening. Galvanizing forms a layer of zinc on the screw surface for protection; nickel plating makes the screw surface brighter and more aesthetically pleasing; blackening improves the wear resistance and corrosion resistance of the screw. ## VI. Quality Control ### (I) Raw Material Inspection Before producing combination screws, strict inspection of raw materials is required. The chemical composition and mechanical properties of the raw materials are checked to ensure they meet requirements and the quality of the raw materials is ensured. ### (II) Production Process Monitoring During the production process, each production step is monitored. Through real-time detection of the dimensional accuracy, thread accuracy, and surface quality of screws by testing equipment, problems occurring during production can be promptly identified and resolved. ### (III) Finished product inspection After production is completed, finished product inspection of combination screws is required. Inspection items include appearance inspection, dimensional measurement, mechanical property testing, and anti-loose performance testing. Only combination screws that have passed strict inspection can be sold on the market. ## VII. Application Scenarios ### (I) Electronics Industry In the production of electronic devices, combination screws are commonly used to connect circuit boards, housings, and other components. Due to the high requirements for connection accuracy and stability in electronic devices, the installation convenience and anti-loose performance of combination screws can meet these requirements. ### (II) Machinery Industry In the manufacturing and maintenance of mechanical equipment, combination screws are widely used for connecting various components. For example, the assembly of engines, transmissions, machine tools, and other equipment cannot be separated from combination screws. ### (III) Furniture Industry In the production of furniture, combination screws are used to connect various components such as frames and panels. The aesthetic neatness of combination screws can improve the overall quality and appearance of furniture. ### (IV) Automotive Industry In automobile manufacturing, combination screws are used to connect components such as engines, chassis, and bodies. Due to the vibration and impact experienced by automobiles during driving, the anti-loose performance of combination screws ensures the reliability of connections between various components of the car. ## VIII. Packaging and Transportation ### (I) Packaging Combination screws are usually packaged in plastic bags, paper boxes, or plastic buckets. The packaging will indicate information such as product specifications, quantity, and material, making it convenient for users to identify and use. ### (II) Transportation During transportation, care should be taken to avoid collision and compression of combination screws to prevent deformation or damage. At the same time, moisture-proof measures should be taken to avoid rusting of the screws. In summary, combination screws are practical and efficient fastening connectors with a variety of types, specifications, and materials to choose from, widely used in various industries. When selecting combination screws, users should consider factors such as screw specifications, material, and quality based on specific usage scenarios and needs, to ensure the reliability and stability of the connection.