Many friends have asked us if we sell "machine screws," but this term is not very scientifically precise. What exactly are machine screws? Simply put, it would be inaccurate to define them as "screws produced by machines." In actual fastener industry practice, the understanding of machine screws is more specific.
Those of us in the industry generally classify machine screws as small-sized screws, specifically referencing standards such as GB/T 818 (cross recessed pan head machine screws) and GB/T 819 (cross recessed countersunk head machine screws). They are called "small screws" because these standards cover sizes starting from M2 (with regular stock) up to M16 in theory, though M16 is rarely used. In common machine screw series, diameters below M8 are most frequently used, which is why they are referred to as small screws.
The term "machine screws" also implies specific thread standards. Typically, machine screws refer to those with standard threads and are not categorized with self-tapping screws. Although self-tapping screws are also small in size, their threads differ significantly from machine screws-machine screw threads are specifically called "machine threads."
"Machine screws" is a broad term that does not specify the material. They can be stainless steel machine screws, carbon steel machine screws, or copper machine screws. Therefore, when purchasing, you cannot simply tell suppliers you need "machine screws"; a clear description is essential.
Machine screws are generally low-priced. In the early days, many fastener factories in Wenzhou produced large quantities of machine screws. Due to quality concerns, Jinrui did not purchase many of these products. To control quality, we mostly produce them ourselves, primarily using stainless steel, with carbon steel as a secondary material.
As part of the small screw series, each size of machine screw has fine threads. For pan head machine screws, the head should be round, the flat surface under the head should be smooth, and there should be no thread-free section where the thread connects to the head. For countersunk head machine screws, the countersink angle must be standardized-after installation, the head should form a flush surface with the base material, ensuring no interference with subsequent surface treatments like powder coating.
