Glossary

A Hardened Round Structural Washer is a specialized type of washer used in heavy-duty structural applications, designed to provide additional strength and load distribution in high-stress environments. These washers are hardened through heat treatment to increase their durability and resistance to deformation under pressure. They are commonly used in conjunction with high-strength bolts in structural steel connections, such as those found in buildings, bridges, and other large infrastructure projects.

A U.S. law enacted to ensure the quality and traceability of certain types of fasteners used in critical applications. The Fastener Quality Act requires that covered fasteners meet specified standards and are tested by accredited laboratories. It also mandates proper documentation and identification, such as lot numbers and manufacturer’s marks, to help prevent the use of substandard or mismarked fasteners in safety-critical environments like aerospace, automotive, and construction.

A progressive mode of failure in a fastener or its material caused by repeated or fluctuating (cyclic) stresses, even when those stresses are below the material's static strength limits. Over time, these dynamic loads lead to the initiation and growth of microscopic cracks, gradually weakening the fastener. This can result in sudden, unexpected fracture without significant prior deformation, making fatigue a critical concern for fasteners exposed to vibration or alternating loads.

The maximum level of cyclic or fluctuating stress that a fastener can withstand for a specified number of cycles without experiencing fatigue failure. This property quantifies a fastener's resistance to the progressive damage caused by repeated loads. It is a critical design consideration for fasteners in applications subjected to vibration, repeated loading/unloading, or other dynamic conditions.

An industrial fender washer is a type of washer that has a much larger outer diameter compared to the inner diameter, which distinguishes it from standard washers. These washers are typically used in industrial applications to distribute the load of a fastener (like a screw or bolt) over a larger surface area. This helps to reduce the risk of damage to the material being fastened and provides better support in situations where the material may be soft or prone to deforming.

A type of stainless steel known for its magnetic properties, moderate corrosion protection, and strength. Ferritic stainless steel contains a high amount of chromium with very low carbon and little or no nickel. It cannot be hardened through heat treatment and is typically used in less demanding environments compared to austenitic stainless steels.

A finished hex nut is a standard six-sided nut used to fasten bolts and screws in a wide variety of general-purpose applications. It is called "finished" to distinguish it from other types of nuts, such as heavy hex nuts, jam nuts, or lock nuts.

A finishing nail is a type of nail designed for use in finish carpentry, where the goal is to fasten materials with a minimal visible nail head for a cleaner, smoother appearance.

A finishing washer is a type of decorative washer used primarily to enhance the appearance of a fastened joint while also providing some functional benefits. It is designed to give a clean, polished look by covering large holes or irregular surfaces around bolts, screws, or rivets.

A flange bolt is a type of bolt that has an integrated flange—a wide, washer-like base—just below the bolt head. This flange distributes the clamping load over a larger surface area, which helps to reduce the need for a separate washer and provides a more secure fastening.

Flat Head Carriage Bolts feature a low-profile head, which allows the fastener to be used in applications requiring minimal clearance. The low-profile design ensures a flush finish and reduces interference with surrounding components. This fastener also features a square section beneath the head, preventing the fastener from turning when the nut is tightened. Flat Head Carriage Bolts are commonly used in the construction of wood or steel garage doors and are used in a variety of other applications and areas across the fastener industry.

A flat O-ring is a type of sealing ring with a flat cross-section rather than the traditional round (torus) shape of a standard O-ring. It combines the sealing function of an O-ring with the low-profile characteristics of a washer or gasket.

A flat washer is a thin, flat, circular piece of metal (or other materials like plastic) with a hole in the center. It is used in conjunction with fasteners such as bolts, screws, and nuts to distribute the load of the fastener over a larger surface area, prevent damage to the material being fastened, and reduce the likelihood of the fastener loosening over time.

A Flat Washer DIN 125A is a standard type of flat washer that conforms to the DIN 125 specification, which is a widely recognized German industrial standard for flat washers. These washers are used in conjunction with bolts, screws, and nuts to distribute the load of the fastener, prevent damage to the surface, and reduce the chance of loosening due to vibration. The DIN 125A flat washer has a simple, flat, circular design with a central hole, and is typically used in general mechanical, industrial, and construction applications.

Flooring nails are specially designed fasteners used to secure wood flooring—such as hardwood or engineered planks—to a subfloor. They are engineered to provide strong holding power while minimizing damage to the wood, especially in tongue-and-groove flooring installations.

Irregularities, laps, or creases in the material of a fastener, typically formed during manufacturing processes such such as cold heading, forging, or thread rolling. These imperfections occur when material flows improperly and folds over itself, rather than flowing smoothly. Folds can appear under the head, along the shank, or in the threads. They are a significant concern because they can act as stress concentrators, weakening the fastener's structural integrity and potentially leading to premature fatigue or fracture under load.

A crack that develops in a fastener's material during its manufacturing process, specifically during shaping operations such as cold heading, forging, or thread rolling. These cracks typically occur when the material is subjected to stresses beyond its formability limits, or due to improper tooling and process parameters. Unlike cracks that develop during service, forming cracks are inherent manufacturing defects that can significantly reduce the fastener's load-bearing capacity and potentially lead to premature failure.

A full thread stud is a cylindrical metal rod that is fully threaded along its entire length, with no unthreaded sections. It is designed to be used in various fastening and assembly applications, where both ends of the stud are screwed into nuts or other threaded components. Full thread studs are commonly used to join two parts or materials together in high-strength, high-tension, or precision applications.