Glossary

The SAE Washers prevent imbedding or distortion to the material being clamped. The washers provide a smooth, level protective bearing surface to fasten nuts and bolts. Without washers, the bolts, nuts, and screws can lose their clamping load if they imbed into the clamping material. SAE Washers are used in assemblies that are bolting together soft metals, wood and steel and are designed to be used with Grade 2 and 5 strength levels fasteners.

An SAE Hardened Flat Washer (RC 38-45) is a flat washer made to SAE (Society of Automotive Engineers) standards, specifically designed to provide extra strength and durability. The washer is hardened to a Rockwell hardness range of 38-45 on the C scale (RC 38-45), making it suitable for use in high-stress or heavy-load applications.

A common strength classification for carbon steel fasteners made from low-carbon steel. SAE J429 Grade 1 fasteners provide the lowest strength level within the SAE J429 standard and are typically used in light-duty, non-critical applications where only minimal strength is needed. Common uses include furniture assembly, light-duty brackets, automotive trim, electrical enclosures, and other non-load-bearing or temporary connections not subject to high stress or vibration. 

A common strength classification for carbon steel fasteners that are made from low to medium carbon steel. SAE Grade 2 fasteners offer a basic level of strength and are typically used in non-critical, general-purpose applications where high strength is not required.

A common strength classification for carbon steel fasteners made from medium carbon steel that are typically quenched and tempered. SAE J429 Grade 4 fasteners provide a moderate strength level under the SAE J429 standard and are commonly used in applications requiring greater strength than Grade 2 but not as high as Grade 5. These fasteners are suitable for general-purpose mechanical and structural applications where improved load capacity is needed. Common uses include automotive components, machinery parts, and light structural assemblies.

A strength classification for medium carbon steel fasteners that have undergone heat treatment to enhance their strength and durability. SAE Grade 5 fasteners provide greater strength than Grade 2 and are commonly used in automotive, industrial, and structural applications where higher load-bearing capacity is required.

A strength classification for alloy steel fasteners that are typically quenched and tempered, conforming to the SAE J429 standard. Grade 5.1 fasteners provide a higher strength level than Grade 5 and are intended for applications requiring enhanced mechanical performance and durability. Common uses include automotive, heavy machinery, and structural applications where improved toughness and tensile strength are necessary.

A strength classification for alloy steel fasteners that are typically quenched and tempered, conforming to the SAE J429 standard. Grade 5.2 fasteners offer a higher strength level than Grade 5.1 and are used in demanding applications requiring superior mechanical performance and durability. Common uses include heavy-duty automotive, industrial machinery, and structural applications where maximum toughness and tensile strength are critical.

A strength classification for alloy steel fasteners that have been heat treated to provide high tensile strength and excellent durability. SAE Grade 8 fasteners are stronger than Grade 5 and are commonly used in heavy-duty automotive, industrial, and structural applications requiring maximum load capacity and toughness.

A strength classification for alloy steel fasteners that are quenched and tempered, conforming to the SAE J429 standard. Grade 8.1 fasteners provide higher tensile strength and improved toughness compared to Grade 8, making them suitable for high-stress, heavy-duty applications. Typical uses include automotive suspension components, heavy machinery, and structural assemblies requiring superior strength.

A strength classification for alloy steel fasteners, quenched and tempered to exceed the mechanical properties of Grade 8.1 under the SAE J429 standard. Grade 8.2 fasteners are designed for extremely demanding applications where maximum strength, durability, and resistance to fatigue are required. Common applications include critical heavy machinery parts, high-performance automotive, and structural components subjected to intense stress.

A classification under the SAE J995 standard for inch-series hex nuts made from low-carbon steel. Grade 2 nuts are intended for use in light-duty, non-critical applications and are typically paired with SAE J429 Grade 1 or Grade 2 bolts. They offer low mechanical strength and usually lack grade markings.

A classification under the SAE J995 standard for inch-series hex nuts made from medium carbon steel, quenched and tempered. Grade 5 nuts are intended for medium-strength applications and are typically used with SAE J429 Grade 5 bolts. They offer greater mechanical strength than Grade 2 nuts and are identified by two circumferential grade markings located 120 degrees apart, typically with one mark on the top face and the other wrapping partially around the side of the nut.

A classification under the SAE J995 standard for inch-series hex nuts made from medium carbon alloy steel, quenched and tempered. Grade 8 nuts are used in high-strength applications and are typically paired with SAE J429 Grade 8 bolts. They provide the highest strength among SAE J995 grades and are identified by two circumferential grade markings located 60 degrees apart, both positioned clearly on the top face of the nut.

An SAE NT Hardened Flat Washer (RC 38-45) is a hardened flat washer made to SAE (Society of Automotive Engineers) standards, specifically designed to withstand high loads and stress in demanding applications. The washer is hardened to a Rockwell hardness of 38-45 on the C scale (RC 38-45), indicating its high strength and resistance to wear. The "NT" in the name stands for "Narrow Thickness", meaning it has a thinner profile compared to standard hardened washers.

An SAE NT2 Hardened Thick Flat Washer (RC 38-45) is a type of hardened flat washer designed to meet SAE (Society of Automotive Engineers) standards with added thickness. The "NT2" indicates a thicker profile compared to standard washers, while the RC 38-45 refers to the washer's Rockwell C hardness rating, meaning it is heat-treated for enhanced strength and durability.

An SAE NTX Hardened Extra Thick Flat Washer (RC 38-45) is a specialized type of flat washer designed to meet SAE (Society of Automotive Engineers) standards, with an extra thick profile for added durability and support. The washer is hardened to a Rockwell hardness of 38-45 (RC 38-45), providing high strength, wear resistance, and the ability to withstand heavy loads and stress.

This laboratory procedure is designed to quickly assess how well fasteners, materials, or their protective finishes withstand corrosion. Within a sealed chamber, these fasteners are exposed to a controlled, corrosive environment. A fine mist or a fog of salt water (typically a 5% sodium chloride solution) is continuously sprayed onto the items at a consistent temperature. This process mimics and accelerates the effects of harsh environmental conditions, allowing manufacturers to determine how resistant a fastener or its protective finish is to rusting and other forms of deterioration over time. The results from these tests are key for quality control, choosing the right materials, and comparing how different protective coatings perform.

A screw is a heavy-duty fastener designed to join materials together by creating its own threads within a material or fitting into a pre-threaded hole. Industrial screws are used in applications such as construction, manufacturing, machinery, and automotive industries, where strong and reliable fastening is required.

A screw eye bolt is a fastener with a looped head and a threaded shaft, commonly used to anchor cables, ropes, or chains into wood. It's often used in light-duty applications like hanging items or guiding wires.

A screw-in anchor is a fastener that creates a secure point in drywall or similar materials for holding screws. It has sharp threads that cut into the material as it’s driven in, providing a strong grip for hanging items like shelves, pictures, or light fixtures.

A pre-applied material on a fastener’s threads that creates a seal to prevent fluid or gas leakage when installed. Unlike locking patches, which focus on preventing loosening, sealing patches are designed to fill gaps between mating threads, providing both a chemical and mechanical seal. They are often used in applications where pressure containment or environmental protection is critical.

Longitudinal surface discontinuities or defects found on fasteners. These imperfections typically originate from flaws in the raw material (such as the wire or bar stock) or are introduced during early manufacturing stages like rolling or drawing. Seams generally appear as straight or slightly irregular lines running along the length of the fastener, commonly located on the shank, under the head, or extending into the threads. They are a significant concern because they can act as stress concentrators, reducing the fastener's fatigue life and serving as initiation points for cracks and eventual failure.

A process used to modify or enhance a fastener after its initial manufacturing. Common secondary operations include drilling, tapping, slotting, shaving, or adding grooves. These steps are necessary when standard cold forming can’t achieve the required detail or precision.

Self-Drilling Screws are versatile fasteners used to attach different materials together, such as metal to metal, metal to wood, and plastic. These screws have a pointed drill bit that allows them to create their own thread without the need for a pre-drilled pilot hole. This feature makes these screws more versatile compared to traditional screws, as they have the ability to tap, similar to self-tapping screws. As a result, Self-Drilling Screws are suitable for use with a wide range of materials across various industries.

A SEMS screw (often capitalized as SEMS) is a type of fastener that combines a screw with one or more permanently attached, free-spinning washers. The term "SEMS" originated from "pre-assembled" and was initially a trademark of Illinois Tool Works Inc., but it's now widely used as a generic term for such assemblies.

A serrated flange bolt is a hex-head bolt with a built-in washer-like flange under the head. The flange has serrations (ridges) that grip the surface to prevent the bolt from loosening due to vibration. It's commonly used in automotive and machinery applications where secure fastening is critical.

A sex bolt, also commonly known as a barrel nut, Chicago screw, or binding post screw, is a two-part fastener designed to join materials securely while providing a neat, flush appearance on both sides.

A shakeproof washer is a type of lock washer designed to stop fasteners from loosening under vibration or movement. Unlike flat washers that only distribute load, shakeproof washers have serrated teeth—either on the inside edge (internal-tooth) or around the outside edge (external-tooth)—that bite into the fastener and the surface material. This added friction helps resist rotation and keeps the joint secure.

They are commonly used in automotive, electrical, and machinery applications where vibration is a concern. While effective, they can mark softer surfaces and aren’t always the best choice for high-strength structural joints, where more advanced locking solutions may be required.

The diameter of the unthreaded, cylindrical portion of a bolt or screw. This precise measurement is typically slightly smaller than the major diameter of the threaded portion. This smaller size provides necessary clearance, enabling the fastener to pass through pre-drilled holes smoothly and aiding in proper alignment before the threads engage, ensuring a proper fit within the assembly.

A shear nut is a type of security fastener designed to prevent tampering or unauthorized removal. It consists of a hexagonal upper section used for tightening and a smooth, conical lower section. During installation, the hex portion breaks off (shears) once a specified torque is reached, leaving behind only the tamper-resistant cone.

Because the remaining section has no grip points for standard tools, shear nuts are extremely difficult to remove without specialized equipment. They are commonly used in security-sensitive applications such as fencing, street signs, utility installations, and other public infrastructure where theft or vandalism is a concern.

The highest level of stress a fastener can withstand before it fails or fractures when subjected to forces that are applied perpendicular to its axis, tending to slide or slice the fastener apart. Shear Strength is crucial for joints where fasteners resist sideways (lateral) loads, such as in structural connections where components might try to slide past each other.

Sheet metal screws are versatile fasteners designed for securing metal, plastic, and other thin materials. They feature sharp, self-tapping threads that cut into material, creating a secure hold without the need for pre-drilled holes in some applications. Earnest Machine offers Type A, Type AB, and Type B sheet metal screws in various head styles to suit different fastening needs.

Short Neck Carriage Bolts feature a shorter, shallower square neck under the rounded head, making them suitable for use with thinner materials like sheet metal. This design prevents damage to the installation surface or connecting material. Due to their versatility, Short Neck Carriage Bolts are commonly used in the assembly of construction equipment, heavy machinery, and furniture where both aesthetics and functionality are important.

A shoulder bolt, also called a shoulder screw, is a type of fastener with a smooth, unthreaded cylindrical section (the "shoulder") between the head and the threaded end. The shoulder acts as a precise guide or pivot point, making it ideal for applications involving moving parts, alignment, or spacing. These bolts are commonly used in machinery, tooling, and automotive assemblies.

A shoulder nut is a type of nut that has an extended, unthreaded cylindrical section (the "shoulder") below the main hex or square body. This shoulder helps locate or align the nut in an assembly, or acts as a spacer or bearing surface.

A Slotted Flat Countersunk Head Cap Screw is a type of fastener designed to sit flush with or below the surface of the material it is securing, thanks to its flat, countersunk head. It features a slotted drive, meaning it has a single straight cut across the head, which is compatible with a flathead or slotted screwdriver. These screws are commonly used in applications where a smooth surface is required after installation, such as in furniture, machinery, and construction.

Jam Slotted Nuts are half as thick as Slotted Nuts. They are designed for low-clearance rotating applications. The slots’ width and depths are manufactured to provide clearance for full engagement of cotter pins or wires — ensuring maximum resistance to loosening.

Hex Slotted Nuts. Castellated Nuts. Slotted Nuts. Whatever you may call them, the nuts perform well under rotating applications. They can be found used in hold bearings and bushing sleeves in place. The castle turret-like features on the top of these nuts permit a cotter pin to lock the nuts in place and prevent loosening.

A slotted reduced-shank screw is a screw with a straight slotted drive and an unthreaded section under the head that’s turned down smaller than the thread’s major diameter—typically near the root diameter. That reduced, smooth shank lets the top material clear the threads so only the far (bottom) material is threaded.

This design pulls joints tight without thread-jacking, lowers driving torque, and reduces splitting in wood, plastics, or thin sheet. The smooth portion can also aid alignment and place the shear plane on solid shank rather than on threads. You’ll see them in cabinetry, plastics assemblies, light machinery, and stacked sheet-metal joints. They’re also called reduced-diameter shank, relieved shank, or waisted screws (distinct from shoulder screws).

A socket head bolt, also commonly known as a socket head cap screw or Allen head screw, is a type of threaded fastener characterized by a cylindrical head and a hexagonal socket (or recess) in the head. 

A solid rivet is a type of mechanical fastener used to permanently join two or more pieces of material together.

A Spanner screw, also known as a Snake-Eye screw, is a tamper-resistant fastener distinguished by its head design, which features two small round holes instead of a traditional slot or cross recess. It requires a special spanner driver with two matching pins for installation and removal, making it difficult to manipulate with standard tools.

These screws are commonly used in public fixtures, electronics, and environments prone to vandalism—such as restrooms, elevators, and playground equipment—where extra security is needed. While they deter casual tampering, they are not entirely foolproof since the drivers are commercially available, so they’re best described as tamper-resistant rather than tamper-proof.

Flat Head Split Drive Anchors offer easy installation and are used in various building materials, such as concrete, brick, mortar, and cement blocks. This fastener is installed into a pre-drilled hole and driven into place using a hammer. A wedging action is created by the crimped f ins on the working end of the fastener, which engages with the walls of the pre-drilled hole, resulting in a secure bond and f lush mounting. With six popular lengths available, Earnest makes it easy to f ind the size needed for your next project.

A split lock washer, also known as a spring lock washer, is a type of washer designed to prevent a nut or bolt from loosening due to vibration or torque. It achieves this by creating tension between the fastener and the material it's securing.

A split rivet, also known as a bifurcated rivet, is a type of rivet distinguished by its split tail, which forms two "legs". This unique design allows for installation without requiring a pre-drilled hole in many cases, especially when joining softer materials.

Square Head Bolts have been a staple in the locomotive industry for generations. In addition to aesthetic appeal, the square head provides a wider surface area to distribute clamping loads. Earnest provides bolts in Grades 5 and 8 for durability and strength. Get modern strength with a classic look.

A square washer, also known as a square plate washer or construction square plate washer, is a flat washer with a square or rectangular shape. Unlike the more common round washers, square washers offer distinct advantages in specific applications, particularly in heavy-duty and structural contexts.

A manufacturing process that shapes or cuts metal by pressing it with a die. In fastener production, stamping is used to create features like heads, slots, or markings quickly and precisely from sheet metal or wire.

The measure of how much force a fastener can withstand before it begins to deform or break. In fasteners, strength level indicates how well the material performs under load and stress. It is usually defined by standardized properties such as tensile strength and yield strength.

Threads on a fastener or inside a hole that have been damaged, worn down, or torn away, preventing proper engagement. Stripped threads cause loose or insecure fastening, reducing the strength and reliability of the connection.

A structural bolt is a specialized type of bolt designed for use in structural applications, primarily in steel-to-steel connections in buildings, bridges, and other structures where safety and load-bearing capacity are critical.

A stud is a type of fastener that consists of a long, threaded rod used to securely join two or more components in construction, manufacturing, and heavy machinery applications. Unlike bolts, industrial studs typically do not have a head and are secured using nuts on both ends or by threading into a tapped hole.

Irregularities or imperfections found on the surface of a fastener that may affect its performance or appearance. These can include cracks, seams, laps, folds, pits, or scratches and are typically caused by issues during forming, machining, or handling. Surface discontinuities are evaluated against industry standards to determine if they are acceptable or if they compromise the integrity of the part.