Exploring the Characteristics and Uses of Stainless Steel Combination Screws
Stainless steel combination screws are classified into two‑component combinations and three‑component combinations, with a wide variety of configurations available.
In a combination screw, the washer(s) must be able to rotate freely without falling off – a design feature that ensures ease of assembly. Because the washers are pre‑assembled, there is no need to match separate flat washers or spring washers during installation. This significantly improves production efficiency and simplifies the assembly process.
There are many types of combination screws. Below are the most commonly used examples:
| Standard Designation | Description |
|---|---|
| GB9074.4 | Cross recessed pan head three‑combination screw |
| GB9074.13 | Cross recessed hexagon three‑combination screw |
| GB9074.17 | External hexagon three‑combination screw |
Materials:
- SUS304 (A2‑70) – The most commonly used material for stainless steel combination screws. It has a moderate work‑hardening rate, good cold‑forming properties, and is suitable for general screws, bolts, nuts, and washers.
- SUS316 (A4‑70) – Contains added molybdenum compared to SUS304, offering superior corrosion resistance, especially against chlorides and acidic media. Also known as acid‑resistant steel, it is particularly suitable for marine environments and chemical applications.
Surface Treatment:
Stainless steel combination screws generally require no additional surface coating. They only need cleaning and polishing. To further enhance corrosion resistance, passivation treatment can be applied.
Different types of stainless steel combination screws are used in different applications:
- Cross pan head three‑combination screws are typically used in small electronic products, such as circuit boards, precision instruments, and compact devices.
- Larger cross hexagon combination bolts are used in larger electrical equipment, such as inverters, frequency converters, and control panels, where they are installed on the housing to allow easy loosening and tightening during maintenance.
Because the washers are captive, installation is straightforward – simply position the screw, align the pre‑assembled washers, and drive it in. This reduces part handling and minimises assembly errors.
Stainless steel combination screws, with their excellent corrosion resistance, high strength, and heat resistance, have penetrated deeply into multiple industrial sectors. Below are the key areas where they play an essential role:
In the electronics industry, circuit boards demand precision and strict conductivity requirements. Stainless steel combination screws, with their stable performance and excellent conductivity, have become the preferred fasteners for PCB assembly. They ensure secure connections without compromising signal integrity or introducing magnetic interference.
In the electrical manufacturing sector – from large household appliances to small consumer electronics – combination screws play a key role in maintaining stable connections between components, thereby improving overall product stability and durability.
In mechanical equipment, especially high‑speed machinery, the stability of fasteners directly affects operational safety. Stainless steel combination screws, with their outstanding fatigue resistance and high strength, ensure that mechanical equipment remains stable and reliable during long‑term operation under dynamic loads and vibration.
Ships operating at sea are constantly exposed to salt spray, humidity, and corrosive conditions. Stainless steel combination screws – particularly those made from SUS316 – provide excellent corrosion resistance, ensuring the structural integrity and safety of ship hulls, deck fittings, and internal systems.
Chemical equipment often comes into contact with aggressive acids, alkalis, and solvents. The corrosion resistance of stainless steel combination screws ensures long‑term stability and reduces the risk of fastener failure in these demanding environments. They are widely used in reactors, pipelines, and storage tanks.
In water conservancy projects – such as dams, sluice gates, and irrigation systems – stainless steel screws are also widely adopted due to their resistance to moisture and chemical attack. They provide a solid guarantee for the safe and durable operation of water management facilities.
Stainless steel combination screws have become an indispensable fastener in modern industry, thanks to their excellent performance and broad application range. Whether in electrical and electronic products, mechanical equipment, shipbuilding, chemical processing, or water conservancy, they are a trusted choice.
Their key advantages can be summarised as:
As technology advances and industries evolve, stainless steel combination screws will continue to play a vital role, supporting progress and reliability across multiple sectors.