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Round head cross three combination screw gb9074.8
- Product description：Cross groove round head three combination screw, also called pan head three combination screw. It has two national standards, namely, two national standard numbers, one is gb9074.8, which is called sm
In daily production and life, the Phillips pan-head triple-combo screw is a common yet crucial fastener. Characterized by its round head (also known as "pan head"), Phillips slot, and integrated design combining a screw, a spring washer, and a flat washer, it is widely used in fields such as home appliances, instruments and meters, and furniture. It is not a single-specification product; instead, it is divided into two core types in accordance with national standards (GB) — the GB9074.8 small pan-head triple-combo screw and the GB9074.4 large pan-head triple-combo screw. These two models have distinct focuses in terms of head size and load-bearing performance, accurately meeting the fastening requirements of different scenarios.
From the perspective of core definition, the "triple-combo" feature of the Phillips pan-head triple-combo screw is its fundamental advantage. Similar to the cylindrical-head hexagon socket triple-combo screw, it is also pre-assembled from a Phillips pan-head screw, an elastic washer (spring washer), and a flat washer, with the three parts firmly integrated into one unit before leaving the factory. This design eliminates the need for separate washer assembly steps, which not only prevents fastening failure caused by workers omitting or misinstalling washers but also significantly improves assembly efficiency, making it particularly suitable for mass production scenarios. Moreover, the combination of the "pan head (round head)" and "Phillips slot" enhances its operational convenience: the pan-head design ensures more uniform force distribution on the head, preventing scratches on surrounding components; the Phillips slot is compatible with universal Phillips screwdrivers, eliminating the need for special tools. This makes daily installation and disassembly more flexible, even allowing for easy use in home DIY scenarios.
As the core difference between the two national standard models, head size directly determines their application scopes. The key feature of the GB9074.8 small pan-head triple-combo screw is its "small pan head," with a relatively smaller head diameter and thickness. For example, for screws of the same specification (such as M4), the head diameter of the small pan-head version is usually 1-2 millimeters smaller than that of the large pan-head one. This compact structure makes it more suitable for scenarios with limited installation space, such as fixing internal components of small home appliances — in the connection between the control panel and the shell of microwave ovens or coffee machines, the narrow internal space cannot accommodate an overly large screw head, while the small pan head can be easily embedded into the installation position to avoid interference with other parts. Additionally, the smaller head reduces its impact on the product's appearance; especially on thin-walled shells that require aesthetic considerations, the small pan head minimizes the obtrusiveness caused by a protruding head. Furthermore, the small pan head has a relatively smaller stress area, making it more suitable for connecting thin components or those bearing light loads, such as plastic casings and thin metal brackets. It can meet fastening requirements without causing deformation of the connected components due to excessive pressure from the screw head.
In contrast, the GB9074.4 large pan-head triple-combo screw is marked by its "large pan head," featuring a larger head diameter and greater thickness, which gives it an advantage in load-bearing performance. A larger head means a wider contact area with the connected component; when tightened, pressure can be more evenly distributed on the surface of the connected component, effectively preventing damage to the component caused by local stress concentration. Therefore, it is more suitable for scenarios requiring high load-bearing capacity or stable connections, such as connecting furniture frames — in fixing the table legs to the tabletop of solid wood desks or joining the side panels of wardrobes with cross braces, the large pan head can transmit tension through its larger contact area, ensuring that the furniture does not loosen easily during long-term use. In fixing the shells of small mechanical equipment, such as the door panels of distribution boxes and tool cabinets, the large pan head can also cope with slight vibrations and external impacts during equipment handling or use by virtue of its stronger load-bearing capacity. Additionally, the large pan head has higher visual recognition; in scenarios where there is no need to hide the screw, its distinct head also facilitates subsequent inspection and maintenance, allowing for quick identification of whether the screw is loose.
Whether it is GB9074.8 or GB9074.4, the "triple-combo" structure of the Phillips pan-head triple-combo screws endows them with shared advantages. The elastic deformation of the spring washer can offset the risk of loosening caused by vibration, preventing the screw from "loosening" during long-term use; the flat washer acts like a "buffer pad," protecting the surface of the connected component from indentations caused by the screw head, and is particularly friendly to soft materials such as plastic and wood. This integrated design of "screw + spring washer + flat washer" also simplifies inventory management for enterprises — there is no need to purchase the three parts separately; instead, enterprises only need to select the corresponding national standard model of the combo screw according to their needs. This not only reduces the types of inventory but also avoids assembly problems caused by mismatched part specifications.
When selecting and using these screws, focus should be placed on distinguishing between national standard models and matching specifications. Firstly, choose the model based on installation space and load requirements: if the space is narrow and the load is light, prioritize the GB9074.8 small pan-head screw; if high load-bearing capacity is required and space is sufficient, the GB9074.4 large pan-head screw is a better choice. Secondly, check the specification parameters, such as screw diameter (M3, M4, etc.) and length, to ensure they match the threaded holes and installation thickness of the connected components. Meanwhile, inspect the integrity of the combo unit to confirm that the spring washer is not deformed, the flat washer is not warped, and the screw threads are not damaged, so as to avoid affecting the fastening effect due to defective parts. During installation, use a Phillips screwdriver of matching specifications to prevent damage to the slot (known as "stripping") caused by mismatched tool size; control the tightening force properly — excessive tightening may cause the spring washer to lose its elasticity, while insufficient force cannot guarantee fastening reliability.
As two classic fasteners standardized by national standards, the GB9074.8 small pan-head and GB9074.4 large pan-head triple-combo screws cover diverse fastening needs from light home appliances to medium-sized equipment with their precise size differentiation and stable performance. Although their structure is simple, they have become indispensable "fastening tools" in industrial production and daily life relying on their "standardized" and "integrated" design, safeguarding the structural stability and usage safety of various products through meticulous details.