Pad eyes are eyelets, rings, or loops that attach to machinery or equipment. They can be used for tie-down, lashing or securing applications, but are not usually rated for overhead lifting.
There are many different types of pad eyes. Examples include welding ring pad eyes, folding pad eyes, eye straps, and anchor plates. Welding ring pad eyes have a diamond, square, oblong, round or saddle-shaped base that maximizes load distribution. They are cast or stamped and made of carbon steel, stainless steel, titanium, or aluminum. Folding eye pads can be used for either temporary or permanent attachment. Because the bails fold down, the angle of applied load prevents bending.
Eye straps have flared edges and are available in many different mounting styles. Channel-mounted eye straps can be attached without drilling holes. Anchor plates are pad eyes that provide a flat or curved base and sized holes that fit specific types of screws.
Materials and Specifications
Although most pad eyes are made of metal, some products are made of injection-molded nylon or acetal resins. Pad eyes have 2, 4, or 6 holes and are available in painted, galvanized or self-colored finishes.
Product specifications include eye inner diameter (ID), eye outer diameter (OD), shoulder diameter, overall length of shoulder, and weight. Some pad eyes are specified in English units such as inches (in) or fractions of an inch. Others are measured in metric units such as centimeters (cm) or millimeters (mm). Blanks are drilled and tapped according to standard sizes such as #10 or #12 screws. With diamond pad eyes, metric thread diameters include 3, 6, 8, 10, and 12 mm. Unified national fine (UNF) threads include 3/16, 1/4, 5/ 6, 3/8 and 1/ 2 in.
In terms of performance specifications, working load is the most important parameter to consider when selecting pad eyes. Most pad eye suppliers specify this amount in English units such as pounds (lbs) or tons, or metric units such as kilograms (kg) or metric tons (Mton). Square pad eyes, oblong pad eyes, round pad eyes, and saddle-shaped pad eyes may carry additional product and performance specifications. ASTM A521, Class CA is a commonly specified standard from the American Society of Testing and Materials (ASTM).