What Is an Eye Bolt?
An eye bolt, also known as a rod-end bolt, is a bolt with a circular or rectangular head that features a hole in the center. Synonyms for eye bolt include “swing bolt,” although “rod-end bolt” is the more commonly used term. Eye bolts, including suspension bolts, are typically used as fittings to attach machinery or other enclosures and are often lifted with a lobe or wire.
Uses of Eye Bolts
Eye bolts are utilized for securing manhole covers during maintenance in factories and power plants and in valves for tightening packing gland seals to prevent fluid leakage. They function similarly to hinges, securing parts that open and close on devices and machines. Since they can be integrated with the device or machine, they prevent the bolt from falling off and allow for easy operation.
Principle of Eye Bolts
Eye bolts are attached by inserting a pin or bolt into the ring hole in the bolt head, allowing the eye bolt to rotate or swing. A nut, wing nut, or knob is screwed onto the threaded portion of the bolt to secure the attached object. Eye bolts are designed to be integrated with the equipment, preventing them from falling off when detached from the threaded hole.
Types of Eye Bolts
Types of eye bolts can be classified as follows:
1. Head Shape
Figure 4. The head shape of the hinge bolt
Eye bolt head shapes can be circular, semi-circular, or rectangular.
2. Dimensions
Figure 5. Dimensions of hinge bolt
The dimensions of eye bolts are primarily expressed in terms of thread outside diameter (D), overall length (L), and thread length (S). The thread length is for a partially threaded part, not a fully threaded part. The hole diameter of the ring may be determined by the screw O.D. or may be pre-processed to the required hole diameter by the user with only a small diameter hole.
The screw’s outer diameter ranges from M6 to M30.
3. Types of Screws
The direction of the screw is right-hand thread or left-hand thread.
4. Material
Common materials for eye bolts include:
- Iron SS400, etc.
- Carbon steel S45C, etc.
- Alloy steel SNB7, etc.
- Stainless steel SUS304, SUS316, etc.
- Titanium steel, etc.
5. Surface Treatment
Surface treatments like uni chrome plating and trivalent chromate treatment are applied mainly to iron, carbon steel, and alloy steel eye bolts to prevent rust and corrosion.