| all-metal lock nut |
A locking nut with deformed threads that add interference to resist loosening. All-metal lock nuts are also called distorted thread lock nuts. |
| assembly |
The process of joining components together into a larger or completed part. Assembly methods include mechanical fastening, adhesive bonding, and welding. |
| bearing surface |
The area of a component that contacts another object. The bearing surface on fasteners is the underside of the fastener head, or the nut, that makes contact with the part. |
| Belleville washer |
A cone-shaped locking washer with a raised section that flattens to prevent loosening without damaging parts. Belleville washers are also called conical spring washers. |
| blind threaded hole |
An internally threaded hole that does not go completely through a material or object. Blind threaded holes are typically used with screws. |
| bolt |
A cylindrical threaded fastener with a head that usually mates with a nut. Bolts typically have blunt ends. |
| brass |
A nonferrous alloy containing copper and zinc. Brass has high tensile strength and corrosion resistance. |
| carriage bolt |
A bolt with a rounded circular head and a square neck. A carriage bolt's square neck prevents the bolt from turning while the nut is tightened. |
| castle nut |
A locking nut with notches cut into the top that are assembled with cotter pins to lock the nut in place.Castle nuts are also called slotted hex nuts |
| chamfered |
Angled or beveled along an edge. Chamfered surfaces allow parts to fit together, remove sharp corners, and protect against damage. |
| chips |
An unwanted piece of metal that is removed from a workpiece. Chips are formed by thread-cutting screws. |
| conical spring washer |
A cone-shaped locking washer with a raised section that flattens to prevent loosening without damaging parts. Conical spring washers are also called Belleville washers. |
| corrosion resistance |
The ability of a material to resist deterioration due to chemical or environmental exposure. Corrosion resistance is one of the most important physical properties for fasteners. |
| cotter pin |
A pin with two ends positioned parallel to each other before use. Cotter pins are inserted through holes and then bent back to lock the pin and other components in place. |
| cup point |
A type of set screw point with an indented tip. Cup points are used for permanent and semi-permanent applications and offer good security. |
| disassembly |
The process of taking apart a product, often with the intention of reassembly. Disassembly is made possible using mechanical fasteners. |
| distorted thread lock nut |
A locking nut with deformed threads that add interference to resist loosening. Distorted thread lock nuts are also called all-metal lock nuts. |
| driving recess |
The indentation on top of a fastener head. The driving recess is designed to accept a matching driving tool. |
| electrical conductivity |
The ability of a material to act as a medium for conveying electricity. Electrical conductivity is aided by the use of tooth lock washers. |
| electroplated |
A coating method that uses electricity and a conductive solution to deposit a layer of plating metal on a metallic or non-metallic workpiece. Electroplated zinc is a common coating on screws. |
| external threads |
Threads formed on the outside of a cylinder. External threads can be found on bolts and screws. |
| fastener |
A device that holds objects together or locates them in relation to one another. Fasteners can be threaded or non-threaded. |
| flat washer |
A common washer that consists of a flat metal disc with a center hole. Flat washers are also called plain washers. |
| flats |
The straight surfaces on the sides of a fastener's head. The flats allow a wrench to grip the head and tighten the fastener. |
| free-spinning lock nut |
A locking nut that creates resistance only when the final torque is applied. Free-spinning lock nuts include special features to provide resistance, such as the locking washer on a Keps nut. |
| grip length |
The length of the unthreaded section of a fastener's shank. Grip length is measured from the bearing surface to the first thread. |
| head |
The end of a fastener that provides a surface for gripping and turning and allows it to bear loads. Head shape and style varies depending on the type of fastener. |
| hex bit |
A hexagonal tool that fits into the head of a drill or screwdriver. Hex bits are used to fasten socket head cap screws. |
| hex bolt |
A bolt with a six-sided head. Hex bolts are the most common type of bolt. |
| hex key |
A hexagonal tool that is used to fasten socket head cap screws. A hex key is a type of wrench. |
| hexagonal |
Having six sides. Hexagonal fasteners like nuts often accommodate a driving tool. |
| interference |
An amount of overlap between two objects. Interference between threads can be used to prevent fasteners from loosening. |
| interference fit |
A tight fit designed so that the smallest permissible shaft is larger than the largest permissible hole. Force is required to assemble parts with an interference fit. |
| internal threads |
Threads formed on the inside of a cylinder or hole. Internal threads can be found in nuts. |
| jam nut |
A thin locking nut that is assembled onto a bolt in addition to a regular nut. The jam nut provides extra resistance that helps prevent the joint from loosening. |
| Keps nut |
A free-spinning lock nut with an attached locking washer. A Keps nut’s locking washer provides extra resistance when tightened to prevent loosening. |
| locking fasteners |
A vibration-resistant fastener that protects against joint loosening. Locking fasteners can be threaded or non-threaded and often use multiple components to lock the fastener in place. |
| locking nut |
A nut designed to prevent loosening of the joint when assembled onto a bolt. Locking nuts are used for joints that require extra security. |
| locking nuts |
A nut designed to prevent loosening of the joint when assembled onto a bolt. Locking nuts are used for joints that require extra security. |
| locking washer |
A washer designed to help prevent joint loosening. Locking washers are used for joints that require extra security. |
| locking washers |
A washer designed to help prevent joint loosening. Locking washers are used for joints that require extra security. |
| machine screw |
A screw with a blunt end that is assembled into a threaded hole. Machine screws are very common threaded fasteners that are similar to bolts. |
| machine table |
The surface on which stock or work is held and located on many types of machines. Machine tables have t-slots that fit t-head bolts. |
| neck |
A square section under the fastener head that prevents slipping and turning after assembly. Square necks are used by carriage and plow bolts. |
| non-threaded fasteners |
A fastener that does not have threads. Common non-threaded fasteners include pins, retaining rings, and rivets. |
| nut |
A fastener with a threaded hole that mates with a bolt. Nuts are often hexagon-shaped to accommodate a driving tool. |
| nylon insert lock nut |
A locking nut with a nylon ring built into the top of the nut. Nylon insert lock nuts add interference to resist loosening. |
| pins |
A thin, often straight, cylindrical non-threaded fastener used to secure the position of two or more machine parts. Pins are inserted through holes. |
| plain washer |
A common washer that consists of a flat metal disc with a center hole. Plain washers are also called flat washers. |
| plow bolt |
A bolt with a flat circular head and a square neck. A plow bolt's square neck prevents the bolt from turning while the nut is tightened. |
| point |
The threaded end opposite the head of a fastener. Points may be flat or pointed. |
| proof load |
A rating that specifies the load that can be applied to a nut and released without causing damage to the nut. Proof load is used to rate nut performance instead of tensile strength. |
| punch presses |
A machine with a stationary base and an upper arm that moves along a vertical axis to shear, bend, or form sheet metal. Punch presses are often used to perform punching and stamping. |
| retaining rings |
A flat, circular, non-threaded fastener with a hollow center and an open section. Retaining rings provide a shoulder and can be inserted onto a shaft or inside a hole with an internal groove. |
| rivets |
A non-threaded fastener that consists of a shank and a head made of deformable material. Rivets are inserted through holes and the shank is formed into a head on the other side of the part. |
| screw |
A cylindrical threaded fastener that either fits into a threaded hole or forms threads in a material. Screws may have blunt or pointed ends. |
| seated |
Fixed in place. Seated free spinning lock nuts provided joint resistance. |
| self-tapping screws |
A screw that forms or cuts threads in materials without pre-tapped holes. Self-tapping screws have pointed ends. |
| SEMs screw |
A locking fastener consisting of a machine screw with an attached free-spinning washer. A SEMs screw typically has a locking washer but may have a plain washer. |
| set screw |
A screw that is usually headless used to lock a component onto a shaft. Set screws come with a variety of points designed to fit into or create a matching recess. |
| shaft |
A long cylindrical bar used to support rotating components or transmit motion. Shaft components are secured with set screws. |
| shank |
The cylindrical length of the fastener that extends from the bearing surface to the point. The shank includes the threaded and unthreaded parts of the fastener. |
| slotted hex nut |
A locking nut with notches cut into the top that are assembled with cotter pins to lock the nut in place. Slotted hex nuts are also called castle nuts. |
| socket |
A hollow tool that fits over a nut or bolt completely. Sockets attach to various devices that are used to tighten or loosen fasteners. |
| socket head cap screw |
A screw that is very similar to a bolt with a driving recess inside the head. Socket head cap screws require a hex key or a hex bit for assembly. |
| split lock washer |
A locking washer with a split section that is intentionally bent out of shape. A split lock washer is forced back into a flat shape as the fastener tightens. |
| square-head bolt |
A bolt with a four-sided head. Square-head bolts are often used in wooden assemblies. |
| stainless steel |
A type of steel that contains more than 15% chromium. Stainless steel has corrosion resistance. |
| steel |
A metal consisting of iron and carbon, usually with small amounts of other elements. Steel is the most common screw material. |
| structural bolt |
A large, heavy-duty bolt used for structural applications in buildings and bridges. A structural bolt is a type of hex bolt. |
| stud |
A cylindrical fastener that has external threads at both ends. A stud does not have a head. |
| tab lock washer |
A locking washer with one or more flat extensions that are bent to lock the washer and nut in place. Tab lock washers may also have more than one hole. |
| tensile strength |
A material's ability to resist forces that attempt to pull it apart or stretch it. Tensile strength specifies the load a fastener can withstand before it breaks. |
| tension |
A pulling force that is directed away from an object and attempts to move, stretch, or elongate it. Tension is applied to fasteners when they are tightened. |
| T-head bolt |
A bolt with a T-shaped head that matches the T-slots in a machine table. T-head bolts rotate to lock the bolt in place. |
| thread length |
The length of the threaded section of a fastener's shank. Thread length is measured from the first thread to the point. |
| thread-cutting screw |
A self-tapping screw that removes material in a hole to create threads. Thread-cutting screws produce chips. |
| threaded fasteners |
A fastener that has threads to hold objects together or grip material. Threaded fasteners include screws, nuts, and bolts. |
| thread-forming screw |
A self-tapping screw that displaces the material in a hole to form threads. Thread-forming screws do not produce chips. |
| thread-locking compound |
A type of liquid adhesive applied to fastener threads to seal the joint and prevent joint loosening and corrosion. Thread-locking compounds are often used with studs. |
| threads |
A raised helical ridge around the interior or exterior of a cylindrical object or hole. Threads help fasteners grip material and hold components together. |
| through holes |
An internal hole that completely passes through an object or material. Through holes are often used with bolts and nuts. |
| tolerance |
The unwanted but acceptable deviation from a desired dimension. Tolerance determines how much an object can vary from the desired dimension and still meet specifications. |
| tolerances |
The unwanted but acceptable deviation from a desired dimension. Tolerance determines how much an object can vary from the desired dimension and still meet specifications. |
| tooth lock washer |
A locking washer with teeth that grip into materials. Tooth lock washers may have internal teeth, external teeth, or both. |
| torque |
A force that causes rotation. Torque is used to tighten threaded fasteners. |
| T-slots |
T-shaped openings that run the length of a machine table. T-slots enable machinists to clamp vises and other workholding components onto the table. |
| twelve-point bolt |
A bolt with a double hex, or twelve-pointed, head. Twelve-point bolts are common in the aerospace industry. |
| washer |
A flat metal disc with a hole through the center. Washers are often used with threaded fasteners to spread the load and control joint tightness. |
| washer face |
The completely flat side of a nut or the bearing surface of a screw head. A washer face is intended to contact the surface of a washer or a part. |
| wrench |
A tool used for fastening nuts and bolts. Wrenches contain fixed or moving jaws or a shaped feature that grips nuts or bolts. |
| zinc |
A bluish white metal that is corrosion resistant and has a relatively low melting point. Zinc is often used as a coating on screws. |