Self - Clinching Glossary of Terms

anvil - An insert, either solid or hollow, which is used on the underside of a panel to resist the installation force.

blind - A hole, usually threaded, which is open from only one end.

broaching - The act of cutting a shape in any object by using a mandrel of a similar shape. As applied to fasteners, the way a knurled shank "broaches" its way into the mounting hole.

captive - The ability of a fastener to remain securely attached to a panel.

captive screw - See: panel fastener.

chamfer - A beveled edge or corner.

cold flow - The movement of a ductile material under pressure.

concealed-head - A type of fastener which, when installed, is completely hidden when viewed from the reverse side.

ductile - Metal which is not brittle and can be easily formed or bent.

floating - The ability of a fastener to move in a direction parallel to the mounting panel and allow for mating hole misalignment.

flush - The ability of a fastener to be contained completely within the thickness of a panel. Also refers to the absence of a protrusion above the surface of the panel.

head - The portion of a fastener which forms its largest diameter.

installation force - A term expressed in pounds, tons or newtons applied axially to a self-clinching fastener to achieve proper installation.

interference fit - The insertion of one member into another whose diameter is slightly smaller than the part being inserted.

knurled clinching ring - The displacer portion of a fastener which has corrugations and is used to develop torque resistance when installed in sheet metal.

locking element - A device employed to restrict rotation of a threaded member while operating in adverse environments, such as vibration and temperature. The nut-locking element provides prevailing locking torque to the mating screw.

minimum distance - The minimum distance from the center of a fastener mounting hole to the nearest edge of a panel which will keep the edge from deforming. This distance may be reduced by suitable fixturing or increasing thickness of panel material.

minimum sheet thickness - The thinnest section of a panel, usually measured in thousandths of an inch or millimeters, into which a fastener may properly be installed. The same fastener may be installed in panels having any thickness greater than minimum.

mounting hole - A properly-sized round opening in a panel to receive the shank of a self-clinching fastener.

panel fastener - A threaded screw which is held captive to a panel and which, when disengaged from its main nut, remains fixed to that panel.

pin - A captive post that extends from a panel.

plunger assembly - A spring loaded device used for latching or indexing purposes.

positive stop - A visual indication that the proper depth of penetration of the knurled ring has occurred or when the "head" is in contact with the top surface of the panel. Synonym: shoulder.

pull-through - The resistance of a fastener to a force applies in the same direction to which is was installed.

punch - A movable insert, either solid or hollow, which applied an installation force to the top of the fastener.

pushout - The force required to remove a fastener from a panel in a direction opposite to the way from which it was installed. Note: pushout is expressed in pounds or newtons.

rockwell hardness - A relative measure of hardness. Rockwell C Scale is used for hard materials, Rockwell B for softer materials, such as sheet metal.

self-clinching (also self-clinch or clinching) - The method by which a fastener is securely attached to a sheet of ductile material by causing the material to cold flow under pressure into an annular recess of the fastener thereby securely locking it in place.

self-locking - A locking element, formed as an integral part of a fastener, which provides force to restrict the rotational movement of a threaded member.

shank - The portion of a fastener, which is slightly smaller than the fastener's mounting hole and provides a positive location for the fastener in the hole. A shank also incorporates an annular groove which becomes filled with panel material as the fastener is installed, and the retention of this material provides pushout resistance.

shank length - The actual length of that portion of a fastener which is embedded in the panel material.

shoulder - The surface area of a fastener which contacts the top surface of the sheet material. See: positive stop.

spring-loaded - A device having a separate movable component that is biased in one direction by a spring.

standoff - A tubular device, usually threaded, for spacing or stacking components.

stud - A male threaded captive post that extends from a panel.

swaging - An operation whereby a reduced diameter of a fastener is deformed to secure it to a panel. Note: the antonym of swaging is self-clinching where the panel material is caused to deform.

thread class - A measure of clearance or fit between the screw and the nut taken at the pitch diameter.

threaded insert - A threaded device which is installed in a panel material.

throughhole - A hole, threaded or not threaded, which transverses the entire length of a part and is usable from either end.

tolerance - The absolute amount of maximum or minimum dimensional deviation allowed that will not affect the performance of a mechanical part.

torque-out - The amount of torque necessary to spin the fastener out of the sheet. This is torque applied to the fastener. No axial load is applied.

torque-through - The amount of torque necessary to fail the fastener in axial load.

undercut - The reduced diameter of a fastener which receives sheet material when a fastener is installed. Depending on the type of fastener, may be rectangular or back tapered in shape.