| adhesive bonding |
The joining of two or more materials through the use of adhesives such as liquids, drops, or gels. |
| axially assembled ring |
A type of retaining ring that is installed parallel to the axis of the shaft or bore in which the ring will be used. |
| bearing surface |
The circular underside of the bolt head that makes contact with the part. |
| blind rivet |
A type of rivet with a tubular shank that is installed from one side of the part. Blind rivets are generally used to simplify assembly and to improve appearance. |
| blind threaded hole |
A type of hole that does not go completely through the material. Most screws are assembled into blind threaded holes. |
| bolt |
A cylindrically shaped, threaded device used for fastening parts. Bolts usually have blunt ends and mate with a nut. |
| bolt head |
The enlarged shape formed on one end of the bolt. The type of bolt head determines the type of tool used to tighten it. |
| bore |
The internal surface of a cylinder. Bore surfaces are often accurately ground to accommodate a retaining ring with minimum friction. |
| burr |
An irregular, rounded mass on an object. |
| capscrew |
A type of screw often used in tapped holes. Capscrews are very similar to machine screws, but they are often made with higher-strength material and to closer tolerances. |
| clamping force |
The compressive force that a fastener exerts on a joint. |
| clevis pin |
A type of semi-permanent pin used to connect a yoke, fork, or eye assemblies in swivel or knuckle-type joints. Clevis pins are usually held in place by cotter pins. |
| coarse thread |
A thick thread. |
| collar |
A coupling device with internal threads designed to attach to another part. |
| corrosion resistance |
The ability to resist a chemical attack on a material by atmosphere, moisture, or other agents. |
| cotter pin |
A semi-permanent pin that fits through a hole in a nut to lock it in place. Cotter pins are generally used when great accuracy is not required. |
| deformable |
To become misshapen when subjected to a type of force. |
| detent mechanism |
A device that positions and holds one part in relation to another so that the device can be released by the force applied to one of the parts. |
| driving recess |
The shape on the top of a fastener head designed to accept a driving tool. A screwdriver is an example of a driving tool. |
| external thread |
A type of thread formed on the outside of a cylinder, such as on bolts and screws. |
| external-type ring |
A retaining ring that fits over a shaft or pin. |
| flat washer |
A type of washer that is slighly oversized allowing it to slide easily over the bolt. |
| friction |
The resistance between the contact surfaces of two objects. |
| gear |
A mechanism for transmitting motion for a specific purpose. |
| grade |
A category, rank, or level of quality. Bolts are classified by grades. |
| grip length |
The length of the unthreaded portion of the bolt shank. |
| hex bolt |
A type of bolt that has a head with six sides. |
| hexagon-head capscrew |
A type of capscrew with a six-sided head. Hexagon-head capscrews are the most common screws in use. |
| housing |
A protective cover designed to contain or support a mechanical component. |
| interference fit |
An amount of overlap between two objects. |
| internal thread |
A type of thread formed in holes, such as in nuts. |
| internal-type ring |
A retaining ring that fits into a bore or housing. |
| large rivet |
A type of rivet with a solid shank and a diameter of 0.500 in. or more. Large rivets are mainly used for structural work on buildings, bridges, or tanks. |
| load |
The amount of force placed upon an object. Bolts must remain tight under loads. |
| lock washer |
A type of washer used under the head of a bolt or nut to grip the fastener to the part's surface. |
| locking lug |
A type of detent mechanism on a push-pull pin. |
| locking nut |
A type of nut that contains a locking element that engages the base surface and creates a tight friction grip against the bolt threads. |
| machine screw |
A type of screw that assembles into tapped holes or nuts. Machine screws are the most general types of screws and are very similar to bolts. |
| major thread diameter |
The distance between the crests of a thread. Major diameter is the widest diameter on a thread. |
| mechanical fastener |
A device that holds two or more objects together. A fastener can be a button or a zipper as well as a bolt or a screw. |
| milling machine |
A machine that uses a multi-point tool to remove metal from the surface of a workpiece. |
| non-threaded fastener |
A type of fastener that does not contain threads. Common types of non-threaded fasteners include pins, retaining rings, and rivets. |
| nut |
A block, usually made of metal, with a threaded hole that mates with a bolt. The outer shape of a nut is often six-sided. |
| pin |
A thin, often straight, cylindrical non-threaded fastener used to secure the position of two or more machine parts. |
| plain nut |
A type of nut that does not provide a self-locking action. |
| plain washer |
Another name for a flat washer. |
| plow bolt |
A square-head bolt often used on heavy construction equipment. |
| point |
The extreme end of the threaded portion of the bolt. The point comes in a variety of shapes. |
| positive-locking pin |
A quick-release pin that has an independent locking action. Positive-locking pins are ideal for quick-change operations. |
| push-pull pin |
A quick-release pin with a solid shank and a detent mechanism backed up by a spring or plug. |
| quick-change operation |
A type of operation in which someone is able to prepare the machine to run another size or type of product quickly. |
| quick-release pin |
A type of pin that is generally used for the manual assembly and disassembly of rigid machine components. Quick-release pins include push-pull pins and positive-locking pins. |
| radially assembled ring |
A type of retaining ring that contains side openings that permit the rings to be placed directly into the groove on the shaft. |
| residual stress |
A type of internal stress that results from cold working, forming, or other means. |
| retaining ring |
A type of non-threaded fastener that provides a removable shoulder to accurately locate or lock parts on shafts, bores, or housings. |
| right-hand thread |
A type of thread that is screwed in by rotating it clockwise. |
| rivet |
A type of non-threaded fastener that consists of a shank and a head made of deformable material. Rivets are inserted through holes and are hammered into a matching head on the other side of the part. |
| riveting |
A fastening process using rivets. |
| screw |
A threaded device used for fastening parts or transferring motion. Screws usually have pointed ends. |
| self-locking ring |
A type of retaining ring that serves mainly as a positioning and locking device. |
| self-tapping screw |
A type of screw that forms or cuts threads in materials without pre-tapped holes. |
| semi-permanent pin |
A type of pin that requires pressure, force, or tools for installation or removal. Semi-permanent pins include straight pins, taper pins, cotter pins, and clevis pins. |
| setscrew |
A type of screw, often with no head, used to hold a sleeve, collar, or gear on a shaft to prevent motion. |
| shank |
The cylindrical part of the bolt that extends from the underside of the head to the point. |
| shoulder |
The part on a retaining ring that positions or limits the movements of parts in an assembly. |
| sleeve |
A tubular part designed to fit over another part. |
| small rivet |
A type of rivet with a shank diameter of less than 0.500 of an inch. Small rivets are often used in the sheet metal and aircraft industries. |
| snap ring |
Another name for retaining ring. |
| socket-head capscrew |
A type of capscrew with a round head and a hexagonal indentation for tightening purposes. Socket-head capscrews are effective in confined spaces where small head size is required. |
| spring steel |
A type of steel, generally made with high carbon, that has high tensile properties. |
| square-head bolt |
A type of bolt with a square-shaped head and a larger bearing surface. Square-head bolts are often used in wooden assemblies and farm machinery. |
| straight pin |
A solid, cylindrical semi-permanent pin mainly used to locate machine parts in a fixed position or to maintain alignment. Straight pins are the most basic pins. |
| structural bolt |
A heavy type of hex bolt intended for use in large structures, such as buildings and bridges. |
| taper pin |
A semi-permanent pin that has a 1/4 inch-per-foot taper on its diameter. Taper pins are often used on parts that require frequent assembly and disassembly. |
| tapered fit |
A type of fit in which the diameter of the fastener gradually decreases to fit into a mating hole. |
| tapped hole |
A type of hole that contains internal threads created by forming or cutting. |
| tensile strength |
The ability of a material to resist forces that attempt to pull it apart or stretch it. |
| T-head bolt |
A type of bolt with a head in the shape of the letter "T." T-head bolts are often inserted into T-slots on the bed of a machine tool. |
| thread gage |
A measuring instrument used to inspect the internal or external threads of a part. |
| thread length |
The length of the threaded portion of the bolt shank. |
| thread-cutting screw |
A type of screw that has cutting edges and produces a mating thread by removing material from the engaged section. |
| threaded fastener |
A type of fastener that contains threads. Bolts, screws, and nuts are examples of threaded fasteners. |
| thread-forming screw |
A type of screw that forms the material around a hole until it wraps around the screw threads. Thread-forming screws do not remove any material from the engaged section. |
| tolerance |
The unwanted but acceptable deviation from the desired dimension. |
| torque |
The amount of force applied to tighten a threaded fastener. |
| T-slot |
An opening in the shape of the letter "T," which can accommodate a T-head bolt. |
| twelve-point bolt |
A type of bolt with a double hexagon head and a low weight-to-strength ratio. Twelve-point bolts are high-strength fasteners often used in the aircraft industry. |
| washer |
A flat disc with a hole through the center that is often used with threaded fasteners to ensure tightness of the joint. |
| weight-to-strength ratio |
The weight of an object divided by its strength. Twelve-point bolts have a low weight-to-strength ratio. |
| welding |
A joining process that uses heat, pressure, and/or chemicals to fuse two materials together permanently. |
| wood screw |
A type of screw with a sharp, pointed end and a tapered shank with sharp threads for penetrating wood. Wood screws come in a variety of styles. |
| wrench |
A tool used to hold or twist nuts and bolts. |