Eye bolts are not commonly encountered in the fasteners we use daily. Limited by design functionality, they are only suitable for specific scenarios. However, precisely because their functionality caters to special needs, their role is irreplaceable by other bolts, and their advantages are quite prominent in practical use.
The current national standard for eye bolts is GB/T 798-2013 (the former GB/T 798-88 has been repealed), and the corresponding German standard is DIN 444. As a type of eyelet bolt, it has a relatively high surface finish, and its thread precision is consistent with conventional thread standards-only its price is slightly higher than that of ordinary bolts. Its specifications range from M6 to M64, but common off-the-shelf specifications only go up to M20; eye bolts of larger specifications need to be custom-made. Due to the limited scope of application scenarios, off-the-shelf inventory is usually insufficient.
Eye bolts are mainly divided into two material types: carbon steel and stainless steel. For carbon steel eye bolts, surface treatments such as hot-dip galvanizing and electrogalvanizing can be applied; for high-strength eye bolts, the surface is mostly subjected to heat treatment followed by oxidation and blackening. Stainless steel eye bolts mainly come in two materials: SUS304 and SUS316.
To fully describe the specifications of an eye bolt, you first need to specify the thread diameter and thread length, then clarify the material requirements; if it is a carbon steel eye bolt, you also need to indicate the surface treatment method. Examples are as follows:
Stainless steel eye bolt: SUS304 stainless steel eye bolt (M8×60)
Carbon steel eye bolt: 45 steel eye bolt (M8×60), with galvanized surface treatment
Both descriptions above fully cover the basic information of the bolts.
The head of an eye bolt is a ring structure similar to that of a lifting eye bolt. During production, the thread part must be processed first, followed by head forging. If the head is produced first and then the thread is processed, subsequent processing interference, inconvenient clamping, and other issues will lead to an excessively high scrap rate in thread processing, which is very unfavorable for efficient production. The head of the eye bolt is formed by hot forging: the material is heated to a specific temperature (approximately 800°C), then extruded and shaped using a mold. Too low a temperature will result in insufficient material deformation, while too high a temperature will affect material strength-therefore, the heating temperature must be strictly controlled.
